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Nutrient dynamics (C, N and P) in termite mounds of Nasutitermes ephratae from savannas of the Orinoco Llanos (Venezuela)
Abstract
Termites play an important role in decomposition processes in savanna and tropical forest ecosystems. In the process of mound building, termites modify the physical, chemical and biochemical characteristics of the soil they use for construction, as well as the soil of nearby areas, so that organic compounds, particularly C and N, and in some cases P, are more abundant in the termite nests than in the surrounding soils. In this study, organic matter and nutrient mineralization in incubation experiments were measured in mounds of Nasutitermes ephratae and associated soils of Orinoco savannas. The mounds of Nasutitermes ephratae contain more C, N and P than adjacent topsoils due to the use of faecal material to build gallery walls. Mounds accumulate 2.25 times more total P than adjacent soils. Available and potentially mineralizable organic P (Po) were significantly higher in Nasutitermes mounds than in adjacent soils. The mound materials significantly stimulated soil microbial metabolism, due to the accumulation of organic carbon (9.30%). The results for nitrogen dynamics emphasise the low ammonification rate in savanna soils. Ammonium production in the savanna soil was very low ranging from 20.4 to 39.9 μg g−1, whereas in the mound the value increases to 1528 μg g−1, which means that as much as 20% of the total nitrogen was found as inorganic nitrogen within the termitaria. Nitrate production on the other hand was negligible in both soils and mound, so that the nitrification rate seemed to be not limited by ammonium production. The nutrient depleted conditions of this environment together with the important concentrations of C, N and P found within the mounds of Nasusitermes ephratae corroborated the hypothesis that termite mounds can act as ‘sinks’ in the nutrient economy of well-drained savannas with low productivity.
... Labile P in > 2 mm aggregates was higher in active mounds than abandoned, especially aboveground, attributed to NaHCO 3 -P o accumulation (Fig. 3a), which is similar to previous studies reporting a gross enrichment of labile P fractions in termitecolonized mounds compared to the below chambers and adjacent soils of various tropical ecosystems (Erens et al. 2015;López-Hernández et al. 1989, 2001Rückamp et al. 2010Rückamp et al. , 2012. This result indicates that large aggregates tend to store active nutrients from plant residue translocation by termites. ...
... This fraction also represents partially hydrolyzed monoester-P having a vigorous capacity for complexing with soil particles which reduces microbial accessibility (Liu et al. 2018). Hence, incorporation of organic residues by termite nesting facilitates the formation of monoester P, resulting in 0.1 M NaOH-P i accumulation at outer wall (López-Hernández et al. 2001). In most cases, 0.1 M NaOH-P i was enriched in termite aboveground mounds relative to the surrounding soils, but was depleted in nests of some Nasutitermes and Cornitermes with a high proportion of monoester-P (Rückamp et al. 2010). ...
... In active mounds (left), P nutrient inputs due to termite grazing belowground, transfers to the aboveground by termite nest building, and finally accumulates in the mound walls, which may improve P cycling. In abandoned mounds (right), P nutrient losses from mound walls aboveground due to erosion and leaching as well as increased microbial mineralization Plant Soil accumulated in most nest walls (López-Hernández et al. 2001;Rückamp et al. 2010). Residual-P is considered to comprise inositol phosphates and is highly stable against microbial and enzymatic attacks (Liu et al. 2018), therefore, its accumulation on the mound surface can compensate for labile P i leaching downwards and P o mineralization loss. ...
Aims
Termites function as “soil engineers” in tropical agroforestry ecosystems. However, of their role in phosphorus (P) cycling little is known. We aimed to investigate the impact of termite activity on soil aggregate stability and P fractions at the aggregate level in a tropical rubber plantation.
Methods
Fungus-growing termite mounds (active and abandoned) involving both above- and belowground locations were studied in a 24-year-old rubber stand. The mass percentage and stability of aggregates, P fractions contents and other major chemical properties of soil aggregates were measured. Aggregate-associated P preservation capacity was also calculated.
Results
More aggregates < 1 mm in size were concentrated in active aboveground mounds than active belowground chambers, thus resulting in weaker stability and erosion resistance, whereas the opposite trend occurred in abandoned mounds. The concentrations of labile P (in > 2 mm aggregate size), moderately labile P (0.25–1 mm), and non-labile P (0.053–1 mm) in active aboveground mounds were significantly higher than other types. The changes in specific P forms enriched TPi in aggregates > 2 mm and TPo in 0.053–1 mm size of active aboveground mounds relative to others, implying the importance of Po storage in microaggregates induced by termite activity involved in long-term P transformation. Furthermore, middle-sized (0.25–2 mm) aggregates stored more P and represented the highest P storing capacity, especially for active belowground chambers.
Conclusions
These results suggest that in the presence of termite activity, P cycling is greatly enhanced in aboveground mounds despite the poor aggregate stability, whereas P forms are stable after mound abandonment, except for a higher H2O-Pi concentration aboveground. Our study provides an important reason why mound soils can be considered as fertility amendments for agroforestry practices in P-deficient tropical soils.
... Termites play an important role in the transformation processes of organic compounds in savannas and tropical forest ecosystems, as a consequence of (i) their significant biomass and diversity within those ecosystems, (ii) their consumption rates and (iii) their effects on the physical, chemical and biochemical characteristics of the associated soils (Lee and Wood 1971;Wood and Sands 1978;López-Hernández and Febres 1984;Nutting et al. 1987;Lavelle et al. 1994;Black and Okwakol 1997;Bignell and Eggleton 2000;Holt and Lepage 2000;López-Hernández 2001). ...
... Mounds act as a sink for some elements and protect those with gaseous phases (N and S) against season-al savanna fires (Wood and Sands 1978;López-Hernández and Febres 1984). A large body of literature discussing the accumulation of nutrients (C, N, P and available cations) in termite mounds and surrounding soils is available (Lee and Wood 1971;Okello-Oloya et al. 1985;López-Hernández and Febres 1984;Abbadie and Lepage 1989;Lavelle et al. 1994;Black and Okwakol 1997;López-Hernández 2001). Evidence suggests that nutrients are accumulated in mounds from the nearby areas; therefore, the abundant termite populations could play an important role in controlling nutrient cycling in tropical savannas, in which available nutrients can often be a limiting factor for plant growth and development. ...
... The important reduction on Psorption capacities is in turn strongly related to the accumulation of organic C in their nests. Organic matter accumulation in mounds is particularly important and affects P dynamics by influencing P sorption-desorption processes (López-Hernández et al. 1989;Frossard et al. 1992;López-Hernández 2001). Phosphorus-sorption processes are strongly reduced in organic matter-enriched mounds compared with adjacent soils, as demonstrated by the competition of phosphates with organic molecules for adsorption sites under laboratory studies (López-Hernández et al. 1986;Frossard et al. 1992;Violante et al. 1996). ...
Nest structures of six termite species, four with epigeous (above-ground) and two with subterranean nests were analysed to find out how their building and feeding habits could be related to their nests phosphorus status compared with control soils. Termite nest structure was found to affect significantly the P status in savanna soils: mounds of the African Trinervitermes geminatus and the South American Nasutitermes ephratae (both grass-feeders) displayed a greater amount of available P, especially in the inner part of the nest, than the surrounding soil. The abundant quantities of dead grass material stored in the mound can explain the available soil P increase. A similar increase in P availability was also found for the soil-feeder Cubitermes severus. In mounds of Macrotermes bellicosus, on the other hand, there was a drastic increase in P sorption (and a corresponding decrease in available P) compared to adjacent soils, which was attributed to the building strategy of this species. M. bellicosus selected clay from subsoil to build its nest structure. The data obtained for the subterranean species Ancistrotermes cavithorax and Microtermes toumodiensis indicated also that there is an increase in P sorption in mounds when compared with associated topsoils. Consequently, the nest structures of only certain termite species should be considered, and utilised, as a soil amendment in place of fertilisers. This impact on the P cycle in savannas seems to be related to the termite feeding status and to the type of material utilised in nest building. This should be taken into account before using termite nest material in soil fertility status improvement.
... For example, Macrotermes falciger nest systems in Zimbabwe were found to have significantly higher concentrations of most measured macronutrients (Ca,K,Mg,NO 3 and S) and micronutrients (B, Co, Cu, Fe, Mn, Mo and Na), and contain significantly more clay particles than the adjacent soil . Similar trends have been recorded for nests systems and matrix soils of several termites including Cubitermes niokoloensis (C,N,NH 4 and NO 3 ), M. bellicosus (C, Ca, K, Mg, N, Na and P), Macrotermes subhyalinus (Ca, K, Mg and Na), and Nasutitermes ephratae (C,N,NH 4 ,NO 3 and P) (López-Hernández, 2001;Ndiaye et al., 2004;Abe et al., 2011;Tilahun et al., 2012). ...
... Alternatively, the termite theory holds that soil nutrient enrichment typical of heuweltjies is primarily a result of termite faecal matter (frass) production, augmented by decomposition of stored plant material, and termite mortality (Matsumoto, 1976;Moore and Picker, 1991;Dangerfield et al., 1998). The nature of heuweltjie soils enrichment (Chapter 3 of this thesis) parallels that of termite-enriched soils elsewhere (Nutting et al., 1987;López-Hernández, 2001;Ndiaye et al., 2004;Abe et al., 2011;Tilahun et al., 2012;Seymour et al., 2014). This has been demonstrated to increase vegetation density (Bloesch, 2008;McAuliffe et al., 2014;Anderson et al., 2016). ...
... The comparative nutrient profile of heuweltjie soils in Worcester (Chapter 4) was found to be intermediate between frass and the associated matrix soils. Heuweltjie nutrient profiles from several sites had higher concentrations of carbon, calcium and nitrogen than their associated matrices (Chapter 3) in addition to being comparable to nutrient profiles of heuweltjies in previous studies (Midgley and Musil, 1990;Kunz et al., 2012) as well as other termites (Nutting et al., 1987;López-Hernández, 2001;Ndiaye et al., 2004;Abe et al., 2011;Tilahun et al., 2012;Seymour et al., 2014). ...
Regular dispersion of termite colonies is suggested to increase stability of biological communities. Our research will test generality of this hypothesis by investigating how the spatial characteristics (e.g. density and dispersion) of heuweltjies (raised earth mounds of the termite Microhodotermes viator) influence ecological processes at various scales. The influence of heuweltjies on primary productivity will be determined at macro-scale using remote imagery to measure photosynthetic activity and fine-scale by comparing plant and animal abundance and diversity on heuweltjies with that in the intervening matrix. Soil enrichment by heuweltjies will be examined at the local scale by quantification of output of termite faecal matter (frass), its macro-nutrient composition, and its contribution to soil enrichment at the landscape scale. In order to assess how density and dispersion (from under- to over-dispersion) influence productivity a remote study of at least 30 sites will contrast productivity among contiguous sites differing only in heuweltjie density and dispersion of heuweltjies. Four sites will be selected for fine-scale assessment of the effects of heuweltjies on plant and animal diversity and abundance of which three are existing SAEON sites (Soebatsfontein, Wolwekraal and Tierberg) where current and historic heuweltjie data is recorded. These data will be linked to differences in density and dispersion to evaluate the hypothesis that more spatially ‘ordered’ termite colonies increase stability of biological communities. Frass production will also be measured at the fourth site (Karoo Desert National Garden, Worcester) where a superficial soil layer has forced termites to deposit most of their frass above their nests (frass production in termites is typically hard to quantify as it is incorporated into the nest itself). This study also aims to show that heuweltjies have a pivotal role in ecosystem functioning in the winter rainfall biomes of South Africa.
... Patches with high accumulation of nutrients can be found in tropical savannahs, known as "nutrient hotspots" as a result of the activities of the soil macrofauna, particularly from earthworms and termites (Arshad, 1982;Lavelle et al., 1994). These hotspots are particularly important in nutrient-poor ecosystems, as is the case of the savannahs of Africa and South America, given their influence on carbon and nutrient cycling (Jones, 1990;Whitford et al., 1992;López-Hernández, 2001;Jouquet et al., 2011, Traoré andJouquet, 2020), on the aggregation and structuration of soils, (Eschenbrenner, 1986;Lavelle et al., 1994;Jouquet et al., 2011) and on the composition and diversity of vegetation through recruitment and dispersal of plants (Glover et al., 1964;Arshad, As far as the latter aspect is concerned, in a savannah woodland of Burkina Faso affected by Macrotermes subhyalinus, Traoré et al. (2008), reported that species richness and density of plantlets were higher on termite mounds than in the adjacent areas, which could be ascribed to the large quantities of materials that termites process in the construction of mounds and strongly influence the physical and chemical properties of soils. These modifications, in turn, have a great temporal and spatial effect on vegetation. ...
... Apart from organic materials, savannah termites usually incorporate mineral particles (usually fine materials) in the construction of their mounds and nests. Once organic materials and fine mineral particles accumulate in the termite mound, they can act as traps for exchangeable forms of the bases thus increasing the fertility of the termite mound (Lee and Wood, 1971a;Watson, 1977;López-Hernández and Febres, 1984;Lavelle et al., 1994;Black and Okwakol, 1997;López-Hernández, 2001, 2003, 2014Kaschuk et al., 2006;Tilahun et al., 2012;Lima et al., 2018;Traoré and Jouquet, 2020). The high accumulation of exchangeable bases in some termitaria may be also due to the use of carbonates from the deeper zone of the soil profile as a construction material (Boyer, 1956;Liu et al., 2007), and to the enrichment of termite mounds in clay materials that keep those bases in their exchange complex. ...
... Several summaries have been published on the use of termite mound powders in agriculture, often with contradictory results without however specifying the type of termite mound in question (Armagnac Bertrand, 2010) [1] . At the same time termite mound materials have been used in traditional cropping systems or in experimental plots in Africa (López-Hernández, 2001; Menea & Ngama Boloy, 1995) [13,14] . The latter underlined the important role of termites in traditional African agriculture. ...
... For Fayle, the roots of certain dicotyledons present an activity of the secondary meristems, this process leads to the increase in the diameter of the roots (Fayle, 1968) [10] . The results of the present study are consistent with those obtained by other studies (López-Hernández, 2001; Menea & Ngama Boloy, 1995) [13,14] . The difference in the degree of fertility that we observed would be due to the origin of the construction materials of the termite mounds. ...
... In turn, the productivity and efficiency of termite mounds is likely to be significantly enhanced by mound-associated communities. It is generally thought that mounds are more carbon-, nitrogen-, and phosphorus-rich than surrounding soils due to the use of faecal material to build mound walls (López-Hernández et al. 1989, López-Hernández 2001, Brossard et al. 2007, Enagbonma et al. 2019). However, mound-associated bacteria may contribute to the availability of these nutrients by mediating carbon fixation, nitrogen fixation, and phosphate solubilization (Lin et al. 2020, Chiri et al. 2021. ...
... Termite nest and mound soils promote growth of a wide range of plants both in natural environments and agricultural settings (Watson 1977, Arshad 1982, Rajagopal 1983, Mokossesse et al. 2012. It was traditionally thought that enhanced fertility is due to the increased nutrients present in nesting structures primarily as a result of termite decomposition (Batalha et al. 1995, López-Hernández 2001, Adhikary et al. 2016). However, increasing evidence suggests growth-promoting microbial communities also play a key role . ...
Termites are a prototypical example of the 'extended phenotype' given their ability to shape their environments by constructing complex nesting structures and cultivating fungus gardens. Such engineered structures provide termites with stable, protected habitats and nutritious food sources, respectively. Recent studies have suggested that these termite-engineered structures harbour Actinobacteria-dominated microbial communities. In this review, we describe the composition, activities, and consequences of microbial communities associated with termite mounds, other nests, and fungus gardens. Culture-dependent and culture-independent studies indicate that these structures each harbour specialised microbial communities distinct from those in termite guts and surrounding soils. Termites select microbial communities in these structures through various means: opportunistic recruitment from surrounding soils; controlling physicochemical properties of nesting structures; excreting hydrogen, methane and other gases as bacterial energy sources; and pre-treating lignocellulose to facilitate fungal cultivation in gardens. These engineered communities potentially benefit termites by producing antimicrobial compounds, facilitating lignocellulose digestion, and enhancing energetic efficiency of the termite 'metaorganism'. Moreover, mound-associated communities have been shown to be globally significant in controlling emissions of methane and enhancing agricultural fertility. Altogether, these considerations suggest that the microbiomes selected by some animals extend much beyond their bodies, providing a new dimension to the 'extended phenotype'.
... Termites are important contributors to carbon and nitrogen cycling in tropical ecosystems. Higher termites digest lignocellulose in various stages of humification with the help of an entirely prokaryotic microbiota housed in their compartmented intestinal tract [4,5,6]. ...
... We will therefore speak of "reconstruction" only if the termites have built a new hat or a dome on the cut surface. The recording of data on the plots was done every six (6) ...
The use of termite mounds as an alternative to chemical fertilizers has grown in tropical developing countries. Termite mounds also play an important role in ecology and these studies were conducted on dynamic of the reconstruction of termite mounds of the genus Cubitermes in the Bondoé savannah from Central African Republic (CAF). The focus on this particular group may be due to their abundance and conspicuous mounds, compared with the diffuse belowground nests inhabited by soldier less soil-feeding termites. The hypothesis of this work was that the termite mounds of Cubitermes (Cubitermes sankurensis and Cubitermes ugandensis) could be reconstructed after removal of hats, trunks at ground level or when termite mounds are dug up 10 cm below the ground. Five (5) experiments were set up to follow the dynamics of the reconstruction of termite mounds during the dry and rainy seasons. The results show that termite mounds with hats removed in one operation rebuild better the following year (25-30% in the rainy season, 50-60% in the dry season). When the removal was done at ground level, an average of 22.5% reconstruction was recorded in the rainy season and 25-30% reconstruction observed in the dry season after one year. Termite mounds dug 10 cm below the ground did not perform better. The removal of hats during the dry season is an option for the rational management of Cubitermes termite mounds in agriculture in CAR.
... Termites play an important role in the transformation processes of organic compounds in savannahs and tropical forest ecosystems (e.g., Lee and Wood 1971;Bignell and Eggleton 2000;Holt and Lepage 2000;López-Hernández 2001). Data on the P content of termite mounds in relation to adjacent soils are sometimes contradictory. ...
... López-Hernández et al. (2006) reported, for neo-tropical termites, significantly higher levels of both total and available P in termite mounds of Nasutitermes ephratae, a common plant-debris-feeding termite, compared with the adjacent soil. Moreover, in a comprehensive P-fractionation study of Nasutitermes, López-Hernández (2001) showed that all P levels were significantly higher in the mounds than in the adjacent soils. Similar results were found when comparing E (t) (the amount of PO 4 that is isotopically exchanged within t minutes) values of isotopically exchangeable P (López-Hernández et al. 1989a). ...
... Studies on soil impact by Nasutitermes sp. revealed that termite mounds can act as source of nitrogen available to plants in nutrient-depleted savanna systems (López-Hernández 2001;Jiménez et al. 2006). The presence of other feeding groups in the peat system (Table 6.1) may also be vital in the optimal functioning of the ecosystem and peat restoration. ...
Termites are the major ecosystem service providers and contribute significantly to soil processes and nutrient cycling in tropical ecosystems. The ecological services provided by termites are often discredited due to their commonly-regarded status as pest in human-dominated landscapes, however. In order to understand the potential roles of termites in peatland ecosystems, termite samplings were conducted in abandoned degraded peatland and peatland cultivated with oil palm in Riau, Sumatra. Surveys found a total of six species of termite of the family Rhinotermitidae. ( rhinotermitid ) in study plots of disturbed lands. In particular, Coptotermes spp . are notorious pests to oil palm, and may also be a potential pest in indigenous tree replanting programs. Based on analysis of termite feeding groups and documentation of wood susceptibility to termite attack, this study provides a reference of tree species that must be avoided in indigenous tree replanting programs so that the trophic relations of termite populations are of most benefit to peatland soil biodiversity and thereby to resilient peatland ecosystems.
... That is so because termites live in populated colonies with a series of intricate galleries where the conditions of humidity (Wiltz et al., 1998) and temperature create an ideal setting for the growth of pathogenic organisms such as fungi. Not exclusively because of these two, but also due to the high content of nutrients in termite nests in comparison with the nutrient-poor surrounding soil environment (López-Hernández, 2001;van der Sande et al., 2018), yet rich in nutrient cycling (Jordan and Herrera, 2015). Among the reasons for the high content of nutrients in nests and their immediate surrounding areas is the way in which nests are built. ...
Termites are key decomposers of dead plant material involved in the organic matter recycling process in warm terrestrial ecosystems. Due to their prominent role as urban pests of timber, research efforts have been directed toward biocontrol strategies aimed to use pathogens in their nest. However, one of the most fascinating aspects of termites is their defense strategies that prevent the growth of detrimental microbiological strains in their nests. One of the controlling factors is the nest allied microbiome. Understanding how allied microbial strains protect termites from pathogen load could provide us with an enhanced repertoire for fighting antimicrobial-resistant strains or mining for genes for bioremediation purposes. However, a necessary first step is to characterize these microbial communities. To gain a deeper understanding of the termite nest microbiome, we used a multi-omics approach for dissecting the nest microbiome in a wide range of termite species. These cover several feeding habits and three geographical locations on two tropical sides of the Atlantic Ocean known to host hyper-diverse communities. Our experimental approach included untargeted volatile metabolomics, targeted evaluation of volatile naphthalene, a taxonomical profile for bacteria and fungi through amplicon sequencing, and further diving into the genetic repertoire through a metagenomic sequencing approach. Naphthalene was present in species belonging to the genera Nasutitermes and Cubitermes. We investigated the apparent differences in terms of bacterial community structure and discovered that feeding habits and phylogenetic relatedness had a greater influence than geographical location. The phylogenetic relatedness among nests' hosts influences primarily bacterial communities, while diet influences fungi. Finally, our metagenomic analysis revealed that the gene content provided both soil-feeding genera with similar functional profiles, while the wood-feeding genus showed a different one. Our results indicate that the nest functional profile is largely influenced by diet and phylogenetic relatedness, irrespective of geographical location.
... Therefore, termite mounds play central roles in nutrient fixation and cycling in terrestrial ecosystems, which has been well documented in the case of C, N, and P cycling (Jouquet et al., 2017;Chen et al., 2018;Jouquet et al., 2020;Chen et al., 2021a;Chen et al., 2021b;Chen et al., 2021c). Previous studies have proposed several hypotheses for differences in nutrient stoichiometry caused by termite mounds, such as the nutrient status of neighbouring soils and their preferential selection, transportation, and ingestion by termites (Jouquet et al., 2007;López-Hernández, 2001;Chen et al., 2018;Chen et al., 2021a;Chen et al., 2021b;Chen et al., 2021c). In this context, mound characteristics may also lead to changes in thriving soil microbial communities and associated microbial processes (Baker et al., 2020); however, termite-microbe interactions and their impact on nutrient cycling processes in tropical ecosystems have been less studied. ...
... These results are in line with findings from other studies where the physicochemical properties of anthill and termite mound soils were analyzed and reported [2,5]. Nyamangara et al. [6] observed that organic fertilizers, such as anthill soil, buffer soils from acidification better than mineral fertilizers and suggested that farmers who use them would benefit from the potential hydrogen (pH) moderation effect, which, in turn, would ensure the availability of nutrients, such as phosphorous, that usually become locked up in acidic soils. ...
... After a fire event during the dry season in the Cerrado, the nitrate from the ashes left on the soil surface solubilizes over the following rainy seasons and can percolate down to a 2.0 m depth through the soil solution (Oliveira-Filho et al. 2018). On the other hand, termites play an important role in the decomposition processes of savannas affecting C and nutrient dynamics; they concentrate nutrients in their mounds, which may reenter soil through leaching (Barnes et al. 1992;López-Hernández 2001;Schwiede et al. 2005;Rückamp et al. 2009;Ngugi et al. 2011). Nevertheless, the leached nitrate can be cycled back to the system since a large portion of roots from Cerrado vegetation are commonly found down to 1.0 m for water uptake during the dry season (Jackson et al. 1999;Quesada et al. 2008). ...
Land use change from Brazilian savanna (Cerrado) to agrosystems has resulted in the depletion of soil carbon (C) and nitrogen (N) pools, despite the adoption of conservation management practices in soybean and maize production systems (SMPSs). This study aimed to investigate a nine-year experiment under SMPSs in continuous succession (DC) and in rotation (CR) with Congo grass, rattlepod, and pigeon pea using a gradient of N fertilizer levels. Soil sampling was conducted down to a 1.0 m depth to measure total and dissolved C and N stocks; topsoil was further evaluated for CO2 evolution in a 500-d incubation assay. Additional soil samples from native Cerrado vegetation were assessed as a reference. Land use change led to 35% and 28% soil C and N stock depletion in the 0–0.2 m layer, respectively, and to a reduction in dissolved forms throughout the soil profile. Although no differences in total C and N stocks between cropping treatments were observed, higher C and N inputs were detected under crop rotation (15% and 28%) and at high N fertilizer levels (14% and 20%). The soil organic matter mineralization assay revealed slower kinetics under CR than under DC, suggesting that further effects on total C and N stocks may occur over longer periods. The stimulated decay of all C pools by 25–175% with increasing N supply reflects the impact that its deficiency has on the cycling of C under these systems. Overall, nine years of soybean–maize succession has not caused a depletion of soil C and N stocks compared with more diverse crop production while providing two annual harvests when N demand is met by fertilization supply.
Graphical abstract
... Dicuspiditermes spp. mounds thus accumulate essential macronutrients and increase soil chemical heterogeneity in tropical habitats (López-Hernández, 2001) and this effect is even more pronounced in human-modified habitats with poor soils such as oil palm plantations (Flynn et al., 2022). Mounds of this termite genus reach mean densities of 100 mounds per hectare in primary forest with relatively rapid turnover (Tuma et al., 2019) with the dead mounds gradually collapsing and thus releasing their nutrients into the environment (Kaschuk et al., 2006). ...
Ants and termites reach high abundances in the tropics and substantially affect the environment through a range of their activities. Because of foraging and decomposition of organic matter at their nesting sites, these locations show fundamentally altered soil properties compared to the adjacent soil. However, such changes are typically studied only within one species or taxon and in one habitat type. Consequently, it is not clear how these effects vary across different taxa and in relation to anthropogenic habitat change. In this study we assess the impacts of different mound-building taxa across a gradient of tropical habitat change in SE Asia comprising primary forest, logged forest and oil palm plantation. To do this we analysed chemical soil properties of mounds of multiple taxa of social insects, with some taxa spanning the full habitat change gradient, and where taxa differ in their mound construction type. Our results show that soils in mounds and adjacent soils have consistently different properties. However, these patterns differ both between social insect taxa and across habitat types. Specifically, mounds of soil-feeding termites Dicuspiditermes spp. were substantially enriched in basic soil nutrients such as C, N, P, especially in oil palm, while mounds of the leaf litter-feeding termite Macrotermes gilvus were depleted. Ant mounds did not show a clear pattern. This indicates that different social insect taxa in a particular habitat affect soil properties in differing ways, and furthermore that such impacts can change when a habitat is anthropogenically altered. Our research highlights the importance of termites for driving the heterogeneity of soil properties and nutrient redistribution across tropical landscapes.
... However, insect effects are often overlooked based on their relative contribution to total biomass across ecosystems, particularly in comparison to plant and microbial biomass 5 . Yet, research has demonstrated that insects can have strong indirect effects on soil and nutrient availability [6][7][8][9][10][11][12][13][14][15] . Still, there remains a large gap in the literature with respect to how less well-studied insects and their behaviors modulate soil habitat and nutrient availability. ...
Current declines in terrestrial insect biomass and abundance have raised global concern for the fate of insects and the ecosystem services they provide. However, the ecological and economic contributions of many insects have yet to be quantified. Carrion-specializing invertebrates are important mediators of carrion decomposition; however, the role of their reproductive activities in facilitating this nutrient pulse into ecosystems is poorly understood. Here, we investigate whether insects that sequester carrion belowground for reproduction alter soil biotic and abiotic properties in North American temperate forests. We conducted a field experiment that measured soil conditions in control, surface carrion alone, and beetle-utilized carrion treatments. Our data demonstrate that Nicrophorus beetle reproduction and development results in changes in soil characteristics which are consistent with those observed in surface carrion decomposition alone. Carrion addition treatments increase soil labile C, DON and DOC, while soil pH and microbial C:N ratios decrease. This study demonstrates that the decomposition of carrion drives soil changes but suggests that the behaviors of insect scavengers play an important role in the release of carrion nutrients directly into the soil by sequestering carrion resources in the ecosystem where they were deposited.
... Similar results were reported by Erens et al. (2015) and Seymour et al. (2014), in which Macrotermes falciger and Diospyros mespiliformis termitaria had a high concentration of nitrates rather than ammonium. However, an opposite result was presented by López-Hernández (2001), who reported that Nasutitermes ephratae mounds had a high concentration of ammonia rather than nitrates. The differences were probably attributable to pH as the pH in mounds enriched in nitrates was usually high, whereas the pH in mounds enriched in ammonium was generally low (Fig. 5a). ...
Fungus-growing termites play a prominent role in nutrient cycling in tropical ecosystems by building numerous mounds with differing properties compared to adjacent soils. However, far less is known about the nutrient variability within the mounds and the nutrient stocks in whole mounds. Here, we investigated the spatial distribution of nutrients and their related nutrient stocks within active mounds (built by Odontotermes yunnanensis), abandoned mounds, and adjacent soils in Xishuangbanna, southwestern China. Detailed sampling was conducted in the vertical section of an active mound, an abandoned mound, and an adjacent soil, and soils were also sampled along the central vertical line from the surface to a 1.60 m layer in four active mounds, four abandoned mounds, and four adjacent soils. The samples were collected along their central vertical line at depths of 0, 10, 30, 50, 70, 90, 120, and 160 cm. We found that, compared to the corresponding values in adjacent soils, the
nutrient stocks (except for NH4+ , exchangeable Na and exchangeable Mg) of organic carbon, total N, exchangeable K, exchangeable Ca, hydrolysable N, available P, and NO3 were increased, on average, by 47.8%, 25.3%, 31.6%, 545.3%, 42.8%, 49.9%, and 620.8%, respectively, in the active mounds. In the abandoned mounds, the nutrient stocks of organic carbon, total N, exchangeable K, hydrolysable N, available P, and NO3 were higher, on average, by 43.5%, 22.4%, 23.3%, 43.7%, 50.4%, and 48.0%, whereas the nutrient stocks of exchangeable Na, exchangeable Ca, exchangeable Mg, and NH4+ were lower by 17.0%, 67.5%, 76.4%, and 44.4%, respectively. High spatial homogeneity and weak or no spatial dependence of nutrient distributions (except for available P and exchangeable cations) were found in the active mounds, whereas high heterogeneity and moderate or strong spatial dependence of nutrient distributions were observed in the abandoned mounds and adjacent soils. The results indicated that the accumulation and spatial distribution of the studied nutrients within
termite mounds were not only related to termite activities but were also affected by environmental factors, such as erosion and leaching, and invasion by plants. Our study demonstrates that termite mounds are“ hot spots” of nutrients and provides evidence supporting conjectures about the homogeneity of physicochemical properties within mound structures.
... Heuweltjies occupy between 14 and 25% of the landscape (Lovegrove and Siegfried, 1986;McAuliffe et al., 2019a;Picker et al., 2007) and are known to contain elevated levels of micro and macro elements, including salts, compared to the surrounding soils (Kunz et al., 2012;McAuliffe et al., 2019aMcAuliffe et al., , 2019bMidgley and Musil, 1990;Midgley et al., 2012). Although heuweltjies are specific to southern Africa, termite mounds the world over are associated with elevated micro and macro elements (López-Hernández, 2001;Seymour et al., 2014). Elevated nutrient levels in groundwater in semi-arid regions of Australia have also been linked to the presence of termite mounds (Barnes et al., 1992;Harrington et al., 1999). ...
Namaqualand, South Africa, is a global biodiversity hotspot but local populations are affected by challenging eco- nomic conditions largely because of poor access to water. In this study groundwater types are characterised and sources of salts and salinisation processes are identified using hydrochemistry and δ18O, δ2Hand 87Sr/86Sr data. Analysis ofδ18Oand δ2H data suggests that evaporation does not play a major role in salinisation of the ground- water. However, major ion chemistry and 87Sr/86Sr ratios indicate that salts present in the groundwater are linked to dry deposition of marine aerosols and ion-exchange reactions in soils in the alluvial aquifer systems. The hydrochemical variability of the groundwater in the basement aquifer system suggests that there are strong local controls linked to weathering processes in individual basement rock types. The region is also notable for the high density of heuweltjies, biophysical features associated with increased nutrient levels, associated with termite activity. Electromagnetic scanning as well as measurement of water-soluble soil electrical conductivity values on and off heuweltjies, show that heuweltjies are saline with salinity increasing with depth. The level of groundwater salinity correlates with the level of heuweltjie salinity. Precipitation records from the last 150 years provide support for the hypothesis that accumulated salts, and in particular, heuweltjie salts are flushed into the groundwater system during sporadic large volume precipitation events. Thus, heuweltjies and hence termite activity, could potentially represent a previously unrecognized contributor to groundwater salinisation across Namaqualand and in other parts of the world
... It is well known that in the process of mound building, termites modify the structural, chemical, and biochemical properties of the soil that they use for construction, as well as the soil of nearby areas, so that some elements (particularly C, N, and P), exchangeable cations (K, Ca, and Mg) and clay content are more abundant in the termite mounds than in adjacent soils (De Bruyn and Conacher, 1990;Holt and Lepage, 2000;López-Hernández, 2001;Jouquet et al., 2002;Sarcinelli et al., 2009). In addition, the bioturbation caused by termite workers during the process of mound building can homogenize soil profiles attenuating typical characteristics derived from local pedogenic processes (Schaetzl and Anderson, 2005). ...
ABSTRACT Regularly spaced earth mounds called “murundus” are scattered in several landscapes in the semi-arid region of Brazil. Although recent evidence indicates that termites are involved in the building of murundus, the contribution of these insects to soil-forming processes in those structures remains poorly understood. In this study, we tested a set of hypotheses to examine whether there are consistent evidence for suggesting the participation of termites in the formation of murundus soils. Morphological and physicochemical features of murundus were compared with adjacent soil profiles in the inter-mounds surface and one epigeic nest built by one species of Syntermes Holmgren. The murundus soils had a more clayey texture, higher contents of nutrients (C, N, P, K, Ca, and Mg) and organic matter compared with adjacent soils. We identified a set of recent and ancient traces inside the murundus that reveals the intense building activity of termite colonies (e.g., galleries, tunnels, and royal chambers), confirming that these structures are not only occupied by these insects but also built-up by them. Taken together, our results provide hard evidence that the long-term activity of mound-building termites was the hierarchically dominant process in producing murundus structures in the semi-arid region of Brazil. Based on available empirical data, we propose an explanatory model on how that construction process may have taken place.
... Los detritos fecales de las termitas tienen bajos contenidos nutricionales, particularmente en N, el cual es eficientemente conservado durante su tránsito a través del tracto digestivo, aunque en muchos reportes se señala un incremento en el contenido de N total en el termitero respecto al suelo adyacente (Lee y Wood, 1971;Abbadie y Lepage, 1989;López-Hernández, 2001) en este respecto Sylvester-Bradley y Gomez (1982) han reportado fijación biológica de N asociada al sistema digestivo de Nasutitermes en el amazonas central. En una reciente publicación López-Hernández (2001) registra para Nasutitermes ephratae, una termita consumidora de gramíneas, muy común en las sabanas del norte de Sudamérica (Colombia, Venezuela y norte de Brasil) niveles significativamente superiores de C (Cuadro 2) y nitrógeno mineral en forma principalmente amoniacal (Cuadro 3), los valores de amonio encontrados en los nidos de termitas ( ~ 1500 µg/g) indican que por los menos el 20% del N total se encuentra como N mineral. ...
Estudios para el Desarrollo de la Agroecología Tropical, Universidad Simón Rodríguez. Venezuela. RESUMEN De los componentes de la macrofauna del suelo las lombrices de tierra y las termitas aparecen como los grupos más conspicuos. En los ecosis-temas templados el primer grupo tiene una activi-dad muy marcada en los procesos de descompo-sición de la materia orgánica (m.o.) e induce cambios de las propiedades físico-químicas y biológicas del suelo a través de los procesos de construcción de túneles y generación de mucus y deyecciones. ABSTRACT Earthworms and termites appear as the most conspicuous components of soil macrofauna. Earth-worms in the temperate ecosystems play a dominant role on the decomposition processes of organic matter (o.m.) inducing changes in the physico-chemical and biological properties of the soil through the construction of galleries and the excre-tion of mucus and casts. A similar role in the decomposition processes of López-Hernández, Venesuelos 11(1-2):15-25
... Organic compounds, particularly those of C, N, and in some cases P, and exchangeable cations are more abundant in termite nest structures than in the surrounding soils. A large body of literature discussing the accumulation of nutrients in termite mounds and surrounding soils is known (Lee and Wood 1971a;López-Hernández and Febres 1984;Okello-Oloya et al. 1985;Lavelle et al. 1994;Black and Okwakol 1997;Holt and Lepage 2000;López-Hernández 2001;López-Hernández et al. 2005). Data suggest that nutrients accumulate in the mound from nearby areas; thus, the abundant termite populations could play an important role in controlling element cycling in nutrient-depleted tropical savannas. ...
Nest structures of two termite species (Trinervi-termes spp.) with epigeal (above-ground) mounds were analyzed to compare their nutrient status with that of adjacent soils. To take into account soil variability, the observations and samplings were made in three toposequences of different and representative West African savanna soils. The data showed the high degree of adaptation of these termite species to a large range of soil types and environments. Mounds of Trinervitermes gem-inatus and Trinervitermes trinervius, both grass-feeders, contained more clay, organic matter (OM), and exchange-able cations than the surrounding surface layer soil. The storage of OM and exchangeable cations was determined for T. geminatus nests and compared to the surrounding soil. Despite substantial nutrient storage in mounds, its total weight appeared low when compared to the nutrient storage in the surrounding 0-15 cm of soil surface layer. This illustrates how contradictory points of view on the use of termite mounds in agriculture need to be clarified using a classical approach that takes into account data by species; and this also evaluates the contribution of different termite mounds to nutrient fluxes and storage and the exact stocking rate of living mounds.
... Quantifying the distribution of termite mounds, regeneration, volume and mass of mound provide useful information on nutrient and minerals, the good productive capacity of the soil and groundwater resource (Turner, 2000;Kaschuk et al., 2006;Ackerman et al., 2007;Mège and Rango, 2010). Research on termite mounds historically concentrated on physicochemical and geomorphological properties (Lee and Wood, 1971;Wood et al., 1983;Abe et al., 2009;Dowuona et al., 2012), and their stability, erodibility, runoff, infiltration rate (Léonard and Rajot, 2001;Jouquet et al., 2012) and physicochemical properties of termite's mound (as a whole) in relation to adjacent topsoil (Hesse, 1955;Brian, 1978;Asawalam et al., 1999;López-Hernández, 2001;Jouquet et al., 2005;Ackerman et al., 2007;Kawaguchi and Nishi, 2007;Asawalam and Johnson, 2007;Jiménez et al., 2008;Okullo and Moe, 2012). As termites bring up soil not only from topsoil but also from subsoil (Jouquet et al., 2002), mound soils are affected by rainfall and thus eroded materials may also affect associated surface soils surrounding the mounds (Arshad, 1982;Lal et al., 1992).This study emphasizes the effect of the mound soil properties on the surrounding surface soil properties and makes a comparison between physicochemical properties of mound soil (at different depth) and surrounding surface soil (non-mound affected soil at different depth). ...
Termites are ecosystem engineers, they play a major role in the biotransformation and modification of soil physicochemical and morphological properties. This study was conducted to evaluate the explored and compared physicochemical & morphological characteristics of soil between termite mounds and surrounding surface soil. Therefore, this study, especially emphasizes the impacts of the mound soil on the surrounding surface soil properties and also to find out the difference between the mound soil properties and surrounding surface soil properties at different soil depth, and characteristic of termite mounds. This study unveils that mound soil properties are directly proportional to the surrounding surface soil properties except for porosity and dispersion ratio. But mound soil properties are not significantly affecting all surface soil properties. The termites have a significant role to change soil physicochemical and morphological properties and there is a significant difference in soil physicochemical properties between mound and surrounding surface soil. However, relatively greater bulk density, clay content, soil pH, organic carbon, nitrogen, exchangeable calcium, exchangeable magnesium, exchangeable sodium, total exchangeable base cations and cation exchange capacity in mound soil than surrounding surface soil. But the relatively lesser value of porosity, dispersion ratio, exchangeable potassium, phosphorus, exchangeable acidity, and C: N ratio is found in mound soil than surrounding surface soil. Conical shaped mounds have greater nutrient concentration than surrounding surface soil. It also highlighted that most of the termite mound consists of trees & bushes containing 8–21 hole or chamber. The termite mounds have granular structure and particle shape are rounded to subrounded, which make them different from surrounding areas. This study suggests and statistically prove that termites have a significant effect on soil properties, they produce physicochemically more quality soil and have an influence on surrounding soil properties.
... In our experiment, pots with termite mound soil had the tallest and greenest C.dactylon individuals compared to other soils, which clearly supports findings of previous work showing that termite mounds are nutrient sinks [1,73] and can strongly enhance grass nutrients and appearance [59]. Cynodon spp. is a frequently found grass in Tanzanian savannas and widely used by wild and domestic grazers in eastern Africa [74,75]. ...
While movement patterns of grazing ungulates are strongly dependent on forage quality their use of nutrient hotspots such as termite mounds or grazing lawns has rarely been quantified, especially in savanna ecosystems where soil-nutrient quality is low. Additionally, few experiments have been conducted to determine the role of termite mound- and grazing lawn-derived soils in improving forage quality in the field. We studied wild ungulate grazing activities around ten termite mounds, six grazing lawns and their respective control sites in a Miombo system of Issa Valley, western Tanzania, in the same system. We used indirect observations (i.e., dung, tracks) to identify seasonal and spatial variations in habitat use of various wild mammalian grazers. Grazer visitation rates were nine and three times higher on termite mounds and grazing lawns, respectively, compared to control sites. During the rainy season, termite mounds were more frequently used than grazing lawns while the latter were used more often during the dry season. In an additional pot experiment with soils derived from different areas, we found that Cynodon dactylon in termite mound-derived soils had twice as high Nitrogen and Phosphorous contents and biomass compared to grasses planted in grazing lawn soils and control site soils. We highlight that both termite mounds and grazing lawns play a significant role in influencing seasonal nutrient dynamics, forage nutrient quality, habitat selectivity, and, hence, grazing activities and movement patterns of wild ungulate grazers in savannas. We conclude that termite mounds and grazing lawns are important for habitat heterogeneity in otherwise nutrient–poor savanna systems.
... De plus, à Lamto, une forte présence des termites dans l'environnement des arbres est souvent observée (Mordelet & Le Roux, 2006) : les arbres poussent en moyenne à proximité des buttes termitiques (Barot et al., 2005). Sachant que les termites sont connus pour favoriser la décomposition dans les savanes et les forêts tropicales (López-Hernández, 2001), on peut s'attendre ici à ce qu'ils rendent plus d'ammonium disponible. D'autre part, le taux de nitrification dans les termitières est plus élevé que loin des termitières (Abbadie, 2006 Ces résultats impliquent que les archées nitrifiantes contribuent probablement fortement à la nitrification aussi bien sous les arbres que sous les graminées. ...
Une savane est définie par la coexistence entre des arbres et des Poacées. Dans la savane de Lamto en Côte d’Ivoire, l’espèce dominante de Poacée est connue pour inhiber la nitrification et avant mon étude, l’impact des arbres sur la nitrification était très mal connu. L’étape de la nitrification est conduite par deux différentes communautés, les archées et les bactéries nitrifiantes ayant le gène amoA. Le but de cette étude est de comprendre l’impact de ces deux types de végétaux sur le cycle de l’azote, notamment sur les communautés nitrifiantes et également de comprendre l’impact de la saisonnalité et du passage du feu sur ces processus. Des échantillonnages ont été réalisés sous les Poacées et les arbres à Lamto durant les saisons humides et sèche et également avant et après le passage du feu. Cela a mis en évidence plusieurs effets : (i) les Poacées dominantes de la savane inhibent la nitrification, (ii) les arbres dominants stimulent la nitrification, (iii) les archées nitrifiantes son prédominantes dans cette savane et elles contribueraient majoritairement à la nitrification, (iv) la saisonnalité à un impact direct sur les abondances et l’activité des micro-organismes du sol (l’activité transcriptionelle des archées nitrifiantes diminuent en saison humide), (v) le feu a un effet indirect sur les communautés microbiennes du sol par son impact sur les caractéristiques physico-chimiques des sols, notamment il diminue l’activité des archées nitrifiantes. Enfin, la dénitrification est supérieure sous les arbres que sous les Poacées. Cette étude a permis de mieux comprendre les interactions entres les bactéries et archées nitrifiantes, la végétation et la saisonnalité.
... This increase in plant growth and rhizome biomass was owned to the high production of the indole acetic acid (IAA), solubilization of phosphate, and production of siderophore by the bacteria. It is of importance to note that termite mound soils hold higher amount of phosphorus when compared to the surrounding soils (López-Hernández 2001). This is because of the highly efficient phosphate-solubilizing bacteria present in termite mound soils (Chakdar et al. 2018). ...
The environmental deteriorating effects arising from the misuse of pesticides and chemical fertilizers in agriculture has resulted in the pursuit of eco-friendly means of producing agricultural produce without compromising the safety of the environment. Thus, the purpose of this review is to assess the potential of bacteria in termite mound soil to serve as biofertilizer and biocontrol as a promising tool for sustainable agriculture. This review has been divided into four main sections: termite and termite mound soils, bacterial composition in termite mound soil, the role of bacteria in termite mound soil as biofertilizers, and the role of bacteria in termite mound soil as biocontrol. Some bacteria in termite mound soils have been isolated and characterized by various means, and these bacteria could improve the fertility of the soil and suppress soil borne plant pathogens through the production of antibiotics, nutrient fixation, and other means. These bacteria in termite mound soils could serve as a remarkable means of reducing the reliance on the usage of chemical fertilizers and pesticides in farming, thereby increasing crop yield.
... Seymour et al. (2014) found similar results in which termitaria of Diospyros mespiliformis were enriched in nitrates but not ammonium. However, the results of López-Hernández (2001) are in contrast, with the mounds of Nasutitermes ephratae enriched in ammonia but not nitrates. The differences are most likely due to mound pH, because the mounds sampled by López-Hernández (2001) were acidic (mean pH = 5.6), whereas the mounds C. Chen et al. ...
... 4.3 3.5 0.8 López-Hernández Cubitermes sp. 6.7 5.7 1.0 & Febre, 1984 Trinervitermes geminatus 7.3 6.5 0.8 López-Hernández, 2001 Nasutitermes ephratae 5.6 4.8 0.8 USA Nutting et al., 1987 Gnathamitermes perplexus (Banks) 7.6 6.8 0.8 Ackerman et al., 2007sp. 4.3 4.4-0.1 Sarcinelli et al., 2009 Lee & Wood, 1971 Amitermes hurensis 5.5 6.6-1 ...
Soil dwelling termites dig nests in the ground that have a significant impact on the soil environment. Activities of termites can result in accumulation of organic matter and enrichment of nutrients and minerals in the soil. Samples from the nest/surrounding soils of two termite species (Odontotermes formosanus (Shiraki) and Reticulitermes flaviceps (Oshima)) and termite non-invaded soils in the seawall of the Qiantang River, Zhejiang Province, China were collected and analysed for soil pH. The results show that the observed termites prefer an acidic environment and that their activities elevate the pH of termite mound soil compared with surrounding soil. Considering the differences in the distribution areas, termite species, and properties of termite mounds and surrounding soils, this paper also examines the literature concerning the effects of termites on soil pH. After summarizing the pH of the termite survival soil environment, the feasibility of termite control by modifying the soil pH is addressed. Finally, some topics for future research are discussed.
... Termites have been identified as common biological agents that produce significant physical and chemical modifications to tropical and subtropical soils (Semhi et al 2008). Termites go through a sequence of actions, from fetching, carrying, to cementing mineral particles into mounds by using their salivary secretion (Lopez-Hernandez 2001). Also, it has been shown that termite activity increases the content of organic matter in the soils that they use for the construction of their nests and also modifies the clay mineral composition of these soil materials (Jouquet et al 2002). ...
Termites mostly feed on dead plant material, generally in the form of wood, leaf litter, soil, or animal dung. About 10% of the estimated 4,000 species (about 2,600 taxonomically known) are economically significant as pests that can cause serious structural damage to buildings, crops or plantation forests. Termites are major detritivores, particularly in the subtropical and tropical regions, and their recycling of wood and other plant matter is of considerable ecological importance. Microorganisms are associated with termites ability to degrade lignocellulose abundant in forest soils. Earlier studies have emphasized the role of termite on soil texture and chemical properties but little is known on the microorganisms associated with termite mounds. The objective of this investigation was to enumerate microorganisms and study fungi occurring in termite mound soils. A comparison of microorganisms occurring in termite mound soil and surface soil adjacent to the mound showed marked variations in number of colony forming units (CFUs). Less CFUs were recorded from mound soil. In both soil samples, actinomycetes were at higher levels than bacteria and fungi apparently due to alkaline pH (±8). Fourteen species of fungi were recorded from termite mound soil whereas 15 were recorded from surface soil adjacent to the mound. Acremonium sp., Aspergillus niger, Humicola sp. and Myrothecium sp. were dominant in mound soil. In contrast, A. niger, A. terreus and a species of Penicillium were dominant in soil adjacent to the mound. Jaccard's similarity index for the fungal species assemblage of mound soil and surface soil was less (21.7%) though the sampling spots were only one meter apart, thus suggesting some substrate preference and adaptability to the specific habitat.
... tissue by termites ( Lee and Wood 1971), leading to higher mound pH levels. Simi- larly, greater levels of P and exchangeable Mg on the mounds can be attributed to the digestion and degradation of plant tissues by termites ( L?pez-Hern?ndez et al. 1989). The foraging behavior of termites can also lead to increasing mound concentrations of soil P ( L?pez-Hern?ndez 2001), due to exposure of P-rich subsoil. In our study, however, exchangeable P did not differ significantly among the three microsites. This may be due to the patchy distribution of P and its lower mobility through the profile, which makes it highly dependent upon depth and location of soil sampling ( L?pez-Hern?ndez et al. 1989). ...
Livestock grazing is a major driver of ecosystem functions in drylands and would be expected to influence soil biota such as termites. We examined changes in soil chemistry and plant community composition on mounds constructed by the subterranean termite Anacanthotermes ahngerianus along a gradient in grazing intensity in an arid steppe in north-eastern Iran. The grazing gradient was represented by increasing distance from an area used by resting livestock, and plant and soil attributes measured within three adjacent microsites (termite mounds, non-mound controls, intervening annular zone surrounding the mounds). Values of soil EC; pH; exchangeable Ca, Mg, and Na; and total nitrogen and organic carbon were greatest in mound soils and declined from mounds to control microsites. Mounds were completely devoid of plants. Annular zones had three-times less cover than the control sites, but there were no differences in diversity or evenness. Electrical conductivity values were ten-times greater on mounds than controls close to resting sites, but the difference diminished rapidly with distance from resting sites. For all other soil and plant variables, differences between microsites were consistent across the grazing gradient. Increased grazing intensity was associated with increasing soil pH, EC and sand content, and reduced plant cover. Overall our study shows that the effects of termites on soil chemistry and plant cover varied little across the grazing gradient. Our results suggest that termite mounds may sustain their role as sites of enhanced soil nutrients under even high levels of grazing.
... Many studies have shown increases in nutrient concentrations, especially nitrogen (N) and phosphorus (P), as wood decomposes [48]. A higher concentration of P and N than in surrounding soils was found in fresh earthworm casts [22], in freshly constructed termite mound materials [27], and in nests of wood ants [8]. Also, higher concentration of N and P than that of wood has been found in faeces of humivorous cetonid beetle larvae Pachnoda ephippiata [24,25], and in the faeces of the wood-feeding scarabaeid beetle larvae Osmoderma eremita [18] and Cetonia aurataeformis [31]. ...
... 또한 열대 산림에서도 유사 연구가 진행되어 흰개미에 의한 유기물 분해 및 양 분 재순환 촉진 현상 등이 보고되고 있다 (Lu et al., 2013;Takamura, 2001 (Park and Bae, 1997;Takematsu, 2006;Yasuda et al., 2000), 방제 방법 (Lee and Jeong, 2004;Ra et al., 2012;Yamauchi et al., 1998;Yoshimura, 2011), 장 내 공생 미생물 및 효소 (Kitade, 2007;Park, 1998;Park et al., 2010) (Engel et al., 2009;Lo and Eggleton, 2011 (Engel et al., 2009;Maynard et al., 2015). (Jones and Eggleton, 2011;Lo and Eggleton, 2011 The difference in C concentration indicates C concentration of termite nests minus C concentration of reference soils (Abe and Wakatsuki, 2010;Abe et al., 2011;Ackerman et al., 2007;Arshad, 1982;Asawalam and Johnson, 2007;Asawalam et al., 1999;Ekundayo and Aghatise, 1996;Ekundayo and Orhue, 2011;Garba et al., 2011;Garnier-Sillam and Harry, 1995;Gosling et al., 2012;Hesse, 1955;Jiménez et al., 2008;Jouquet et al., 2004;Jouquet et al., 2005;Kang, 1978;Kaschuk et al., 2006;López-Hernández, 2001;Maduakor et al., 1995;Menichetti et al., 2014;Ndiaye et al., 2004;Park et al., 1994;Sarcinelli et al., 2009;Sarcinelli et al., 2013;Traoré et al., 2008;Traoré et al., 2015;Watson, 1975;Wood and Johnson, 1983 Martius et al., 1993;Nunes et al., 1997;Sanderson, 1996;Sugimoto et al., 1998 (Brune, 2010). ...
... The clay percentages of the Stellenbosch soils on the heuweltjies were significantly higher than those of the adjacent surrounding soils (Table 3). This result can be attributed partly to the fact that the termites selectively transport clay particles from other horizons into their nests and combine it with faecal material to build their tunnels and gallery walls (López-Hernández, 2001). Evidence of the natural soil-forming process of clay illuviation is absent in the soil of the heuweltjies, due to bioturbation caused by the termites. ...
Heuweltjies are unique landscape features putatively created by the termite Microhodotermes viator through their burrowing and nest-building activities. They have been closely examined in the natural veld of the Western Cape in the recent past and are the focus of many ecological studies, but their effect in cultivated landscapes (e.g. vineyards and orchards) has remained unexplored. This study addresses the vigour and physiology of vines growing on and offheuweltjies, as well as the wine emanating from these vines. This study was conducted on Cabernet Sauvignon and Shiraz in two climatic regions of the Western Cape, namely Stellenbosch (Mediterranean climate) and Robertson (semi-arid climate) respectively, to better understand how differences in heuweltjie characteristics correspond to differences in rainfall and temperature. Through the use of ANOVAs and Fisher's LSD post hoc tests to indicate statistical significance, it was apparent that the soil on and offheuweltjies differed significantly in respect of several physical and chemical properties. Consequently, soil water content was more favourable on heuweltjies, especially in the Stellenbosch area, where only supplementary irrigation was applied. Heuweltjies induce substantial changes in grapevine vigour and grape composition. Differences in grapevine physiology between heuweltjie and non-heuweltjie plots were subtle, but vine vigour was severely altered on the heuweltjieassociated vines, exhibiting excessive vegetative growth in Stellenbosch and leading to variations in berry and wine characteristics on and offthe heuweltjies. The opposite was observed in the semi-arid climate of Robertson. The presence of heuweltjies in vineyards presents an opportunity to produce and market wines with a difference in respect of their characteristics and unique origin.
... Although several studies have shown termite mounds to contain elevated soil nutrients, few studies have examined mineralization rates and temporal dynamics of soil nutrients on termitaria relative to the surrounding matrix (e.g., Jim enez et al., 2008;L opez-Hern andez, 2001). Where mineralization has been examined, studies were carried out over short periods which limits our understanding of the role of termites in nutrient cycling over long periods. ...
Termites through mound construction and foraging activities contribute significantly to carbon and nutrient fluxes in nutrient-poor savannas. Despite this recognition, studies on the influence of termite mounds on carbon and nitrogen dynamics in sub-tropical savannas are limited. In this regard, we examined soil nutrient concentrations, organic carbon and nitrogen mineralization in incubation experiments in mounds of Macrotermes falciger and surrounding soils of sub-tropical savanna, northeast Zimbabwe. We also addressed whether termite mounds altered the plant community and if effects were similar across functional groups i.e. grasses, forbs or woody plants. Mound soils had significantly higher silt and clay content, pH and concentrations of calcium (Ca), magnesium (Mg), potassium (K), organic carbon
... Numerous publications are discussing the accumulation of nutrients in termite mounds and surrounding soils (e.g. Brossard et al. 2007;Lavelle et al. 1994;López-Hernández 2001;). ...
The consequences of habitat change for human well-being are assumed to be especially extreme in Burkina Faso. The country is located in a highly drought-sensitive zone of West Africa, and small‐scale subsistence farmers may be especially affected if losses of biodiversity lead to changes in ecosystem functioning; many depend on more or less degraded lands for agricultural production.
The overall aim of the present thesis consequently was to characterize the functional traits of soil-organisms which are crucial for a productive and balanced soil environment in the study region – termites and ants. They are true ecosystem engineers whose activity alters the habitat. Through soil-turnover in the course of constructing biogenic structures of varying size and nature (mounds, nests, galleries, soil-sheetings, foraging-holes), they bioturbate huge amounts of soil masses and exert massive effects on soil structure, positively influencing the fertility, stability, aeration and water infiltration rate into soils; and they provide habitats for other species. In sub-Saharan Africa, ants and termites are the only active soil macrofauna during the long dry season; in the sub-Sahel zone of Burkina Faso, termites even represent the only active, quantitatively remarkable decomposers all year round. Since no information was available about the actual diversity of the focal arthropods, I divided the thesis in two main parts: In the first part, a baseline study, I assessed the local termite and ant fauna, and investigated their quantitative and qualitative response to changing habitat parameters resulting from increasing human impact (‘functional response traits’). In the second and applied part, I addressed the impact of the biogenic structures which are important for the restoration of degraded soils (‘functional effect traits’).
Two traditional agricultural systems characteristic for the study region were selected. Each system represented a land-use intensification gradient comprising four distinct habitats now differing in the magnitude of human intervention but formerly having the same initial state. The first disturbance gradient, the temporal cross-section of a traditional soil water conservation technique to restore degraded heavily encrusted, barren soil named Zaï in Ouahigouya (Yatenga province, sub-Sahel zone); the second disturbance gradient, an agriculture type using crop rotation and fallow as nutrient management techniques near Fada N’Gourma (Gourma province, North-Sudanese zone).
No standard protocol existed for the assessment of termite and ant diversity in semi-arid (agro-) ecosystems; two widely accepted standard protocols provided the basis for the newly revised and combined rapid assessment protocol ‘RAP’: the ALL protocol for leaf litter ants of Agosti and Alonso (2000), and the transect protocol for termites in tropical forests of Jones and Eggleton (2000). In each study site, three to four replicate transects were conducted during the rainy seasons (2004—2008).
The RAP-protocol turned out to be very effective to characterize, compare and monitor the taxonomic and functional diversity of termites and ants; between 70% and 90% of the estimated total species richness were collected on all levels (transects, habitats, regions). Together in both regions, 65 ant species (25 genera) and 39 termite species (13 genera) were collected. These findings represent the first records for Burkina Faso. The data indicate a high sensitivity of termites and ants to land-use intensification. The diversity strongly decreased with increasing anthropogenic impact in the North-Sudan region. In total, 53 ant species (23 genera) and 31 termite species (12 genera) were found. Very promising results concerning the recovery potential of the soil-arthropods’ diversity were gathered in the Zaï system. The diversity of both taxa strongly increased with increasing habitat rehabilitation – in total, 41 ant species (16 genera) and 33 termite species (11 genera) were collected. For both taxa significant differences could be noted in the shape of the density variations along the gradient. For instance termites: Fungus-growers showed the greatest adaptability to different management practices. The greatest variations between the habitats were observed in soil and grass-feeding termites. Whole functional groups were missing in heavily impacted habitats, e.g. soil-, grass-, and wood-feeders were absent in the degraded site in the sub-Sahel zone. Several environmental parameters could be identified which significantly explained a great part of the variations in the composition of the arthropods’ communities; they indicate the importance of the habitats’ structural complexity (vegetation structure) and concomitant effects on diurnal temperature and moisture fluctuations, the availability of food sources, and the soil-structure. The diversity of termites in the sub-Sahel region was strongly correlated with the crown-cover percentages, the topsoils’ sand-content, and the availability of litter; in the North-Sudan region with the cumulated woody plant basal area, the topsoils’ clay- and organic matter-content. The parameters identified for ant communities in the Zaï system, were the height of trees, the topsoils’ clay-content and air humidity; in the North-Sudan region the habitats’ crown-cover percentages, the quantity of litter and again the height of trees.
In the second part of the thesis, I first rapidly assessed the (natural) variations in the amount of epigeal soil-structures along the two disturbance gradients in order to judge the relative importance of termites and ants for soil-turnover. The results illustrated impressively that a) in all study sites, termites were the main bioturbators while ant structures were of minor importance for soil turn-over; b) earthworms and grass-feeding termites contributed significantly to soil turn-over in the more humid North-Sudan region; and c) the bioturbated soil mass varied between seasons and years, however, the relative importance of the different taxa seemed to be fairly constant. In the sub-Sahel zone, fungus-growing Odontotermes and Macrotermes species fully take over the important function of bioturbation, leading to the transport of huge amounts of fine-textured soil material to the surface; with increasing habitat restoration, coarse fragments decreased in the upper horizons and became concentrated deeper along the soil profile.
Consequently, in the applied part, I concentrated on the bioturbation activity of fungus-growing termites in the four main stages of the Zaï system: crusted bare soil (initial stage), millet field, young and old forest. In each of the four Zaï sites nine experimental blocks (each comprising four plots of 1m2) were used to stimulate the foraging activity of fungus-growing termites with different, locally available organic materials (Aristida kerstingii hay, Bombax costatum wooden blocks, compost and a control without any organic amendment). The experiment was conducted twice for the duration of four weeks (rainy season 2005, dry season 2006). The plots were regularly checked and the increase of the area covered by sheetings chronologically followed. After four weeks a) all sheeting-soil was collected, air dried and separately weighed according to the different genera, and b) the foraging-holes were counted and their diameter measured. Additionally, c) ponded water infiltration was measured in selected plots, and d) the physicochemical properties of sheeting-soil were analyzed. In case of complete consumption of the offered hay during the experimental 4-weeks-duration, the same procedure (a, b) was followed before adding new hay to the respective plot.
The comparison between the different plots, sites and seasons revealed clearly that hay was the most attractive bait; for each gram of hay removed, Odontotermes brought about 12 g soil to the surface, Macrotermes 4 g. Odontotermes was the only genus attracted by organic material to the degraded area, and was therefore the decisive primary physical ecosystem engineer in the Zaï system, initiating the restoration process. The mass of soil bioturbated in the course of foraging increased strongly from the degraded, barren towards the most rehabilitated reforested site. Combining all 36 experimental plots per Zaï stage, Odontotermes bioturbated 31.8 tons of soil per hectare and month dry season in the degraded area, and 32.4 tons ha-1 mon-1 in the millet fields; both genera moved 138.9 tons ha-1 mon-1 in the young and 215.5 tons ha-1 mon-1 in the old Zaï forest. Few comparable figures were found in the literature. In northern Burkina Faso, both genera constructed 20 tons of sheetings ha-1 mon-1 after mulching with a straw-wood mixture (Mando & Miedema 1997), and in Senegal, around 10 tons ha-1 mon-1 were moved in heavily foraged plots (Rouland et al. 2003). Within a site, soil turn-over and the number of foraging holes created was always highest in hay, followed by compost, then by wood and in the end control. The fungus-growers’ foraging-activity was leading to an enormous increase in surface pore space – after one month of induced foraging activity in hay-plots, the median number of foraging-holes increased from 142 m-2 in the degraded site up to 921 m-2 in the old Zaï forest. The creation of subterranean galleries and macropores significantly increased the water infiltration rate by a mean factor 2–4.
Laboratory analyses revealed that sheeting-soil differed strongly from the respective control soil as well as between the seasons, the food-type covered, and the two genera. Odontotermes-sheetings differed in more parameters than Macrotermes-sheetings, and dry season sheetings differed in more parameters (and more strongly) than rainy season sheetings. In the present study, soil organic matter, carbon and nitrogen contents were significantly increased in all dry season sheetings; in the rainy season mainly in those built on compost. Texture analysis pointed out that both genera used topsoil and soil from deeper horizons in varying mixture ratios, thereby supporting findings of Jouquet et al. (2006).
To summarize, the present thesis contributes to a better understanding of the functional response traits of termites and ants to changing environmental parameters resulting from increasing human impact. The RAP-protocol represents an easy-to-learn and very effective method to representatively characterize, compare and monitor the taxonomic and functional diversity of termites and ants. The experiment has provided conclusive evidence of the importance of the consideration of fungus-growing termites (particularly Odontotermes and Macrotermes species) when aiming to restore infertile, degraded and crusted soils and to maintain a sustainable agricultural production in the Sahel‐Sudanese zone of West Africa.
... , kadar air sarang dan tanah sekitar sarang lokasi itian relatif sama dan Porositas Rayap Macrotermes dan Tanah Taman sekitar sarang. Dilihat musim ini diduga meningkatkan jumlah N total dalam tanah dan ballan organik yang merata di seluruh (Hernandez, 2001). areal menyebabkan kandungan karbon organik dalam tanah lebih pada sarang memiliki keragaman paling keeil, sehingga kadar air tanah pada lokasi tersebut dikatakan lebih di setiap titik. ...
... En la EBL ha sido reportada una mayor actividad de termiteros y de hormigas (San José et al., 1989), que podría contribuir a disminuir los niveles de C en el suelo, al acelerar los procesos de descomposición-mineralización (López-Hernández, 2003). Los termiteros de especies forrajeras como las que se encuentran en EBL, poseen un contenido de materia orgánica varias veces superior a los del suelo circundante y esta acumulación de C orgánico ocurre a expensa del C existente en los alrededores del termitero (López-Hernández, 2001). Si bien, este último resultado parece contradictorio, hay que resaltar que la información existente en la literatura al respecto es variable. ...
... Zheng et al. (2004), however, after ten annual applications of mineral fertilizers and liquid dairy manure in a Humic Cryaquept in Québec, Canada, found that there was no effect on HCl-P and H 2 SO 4 -P fractions, meaning that P additions for 10 years had a limited effect on the sparingly soluble P pools. Nonetheless, López-Hernández (2001), when analyzing P accumulation in savanna termite mounds, showed differences in residual P between mounds from grass feeding termites and associated soils. Cross and Schlesinger (1995) reported that plant-available P or labile P fractions (e.g. ...
In Venezuelan Amazonian, some producers have established small agroforestry systems of production on sandy savanna soils by a long-term addition (more than 25 years) of animal manures at a low dressing (2 Mg ha −1) as fertilizer input. As a result of the organic fertilizers regime, the original savanna soil has been changed in terms of soil quality parameters. The main objective of the study was to investigate using sequential fractionation of soil P the impact of organic manures on the amount and partitioning of bioavailable P in soils of the Amazonas. Fractionation was carried out on Typic Ustipsamments amended with three different organic manure sources for extended periods. In general, after fertilization, all Pi and Po fractions increased significantly. The increase was striking in the resin-Pi and HCl-Pi, and among the organic P fractions, the changes were highest for the NaOH-Po sonicated and non-sonicated fractions. The total P increment was more relevant when soils were amended with chicken manure (1,194 mg Pt kg −1) and less relevant for the farm soil treated with compost (500 mg Pt kg −1), where the soil amended with cattle waste presented an intermediate value in total soil P (851 mg Pt kg −1). The importance of this field study was to assess the sustainability of long-term established organic management characterized by the low inputs, and this information is poor in the Amazonas.
Water management is an important aspect for hydrological restoration in the tropical peatland because the availability of water is not evenly distributed in the dry and rainy seasons. The aim of this study was to conduct action research focusing on water management for integrated peatland restoration at Pulau Tebing Tinggi Peatland Hydrological Unit (PHU), Riau, Indonesia. The actions were to implement some research results and findings by developing demo-plots for a pilot project and analyzing their impact. The pilot project for water management was developed at Pulau Tebing Tinggi PHU not only for the purpose of peat rewetting, but also to support revegetation efforts and revitalization of livelihood. Pulau Tebing Tinggi PHU, located in Kepulauan Meranti Regency, Riau Province, is susceptible to peat fires. In 2014, big peat fires occurred in Pulau Tebing Tinggi PHU and several peatland areas in Riau, causing a haze disaster that lasted for about 2 months. The disaster produced a sickening and deadly cloud of smoky pollution that not only threatened Indonesia but also neighboring countries.
The Thornthwaite-Mather water balance (TMWB) model was applied for water balance analysis as a basis for water management in the research site. A masterplan for water management was developed which was integrated with revegetation and revitalization of livelihood approaches. Canal block constructions, paludiculture, and aquaculture were the integrated activities carried out to support peatland restoration. Two types of canal blocks, whose main materials were wood and vinyl sheet pile, were introduced in this pilot project. Four key parameters of peatland restoration progress were monitored periodically, namely water table, land subsidence, CO 2 emissions, and vegetation growth. This research found that by applying water management properly, the water table can be maintained at a stable and high level in wet peatlands. Water management by applying canal blocking has a good impact for keeping groundwater elevation and keeping peatland in a wet condition for a distance of 400 m upstream from the canal block.
Termites represent one of the most important insect groups worldwide due to their key role as plant decomposers and proxy of carbon recycling in the tropical rainforest ecosystems. Besides, high relevance in research has been given to these social insects due to a prominent role as urban pests. However, one of the most fascinating aspects of termites are their defence strategies that prevent the growth of detrimental microbiological strains on their nests. One success factor is the key role of the nest allied microbiome. Understanding how beneficial microbial strains aid termites in pathogen biocontrol strategies could provide us with an enhanced repertoire for fighting antimicrobial resistant strains or mine for genes for bioremediation purposes.
We carried out a multiomics approach for dissecting the nest microbiome in a wide range of termite species, covering several feeding habits and three geographical locations at two tropical sides of the Atlantic Ocean, and an African savanna. Our experimental approach included untargeted volatile metabolomics, targeted evaluation of volatile naphthalene, taxonomical profile for bacteria and fungi through amplicon sequencing, and further dive into the genetic repertoire through a metagenomic sequencing approach.
Volatile naphthalene was present in species belonging to the genera Nasutitermes and Cubitermes. We further assessed the apparent differences in terms of bacterial community structure, having found a stronger influence from feeding habits and genera, rather than the geographical location. Lastly, our metagenomic analysis revealed that the gene content provides both soil feeding genera with similar functional profiles, while the wood feeding genus shows a different one. These results seem to be independent of the geographical location, indicating that the nest functional profile is heavily influenced by the diet of the termite inhabiting, building, and maintaining the nest.
Soil is essential to agriculture and a resource that cannot be replaced easily. Nevertheless, its importance to food production and the threats to its sustainability are often overlooked. This book, the 35th volume of Issues in Environmental Science and Technology, examines the current status of soils across the globe and their potential for food production to meet the needs of the World's population in the 21st Century. Threats, such as the degradation, pollution and erosion of soil are discussed, along with the possible consequences of climate change for soil and food production. As an ecosystem service, soil also serves to capture nutrients and sequester carbon, and these issues are discussed in the context of adding value to soil protection. The influence of modern agricultural techniques in enhancing soil productivity is also discussed. Throughout the book case studies support the discussion. Together with the books on Ecosystem Services, Sustainable Water, and Environmental Impacts of Modern Agriculture, this addition to the series will be essential reading for anyone concerned with the environment, whether as scientist, policy maker, student or lay reader.
African termites are classified into five distinct families, Termitidae, Rhinotermitidae, Hodotermitidae, Termopsidae and Kalotermitidae. Termites are undoubtedly one of the key ecosystem engineers. Because they harbour more nutritive plants, herbivory by large herbivores is biased towards mounds. Their engineering role is visible through construction of conspicuous termite mounds, which often harbour some unique species compared with the expansive ecosystem in which they occur. To understand the cascading effects of termite mounds on ecosystem functioning, we present a review on how termites create ecosystem heterogeneity, and how this heterogeneity in terms of soil physical and chemical characteristics, particularly nutrients, further influences vegetation production, diversity and palatability to large herbivores. Here we review literature mainly focusing on: (i) Phylogeny (evolutionary history) of African termites, (ii) mound construction, (iii) mound spatial distribution, (iv) termite foraging (v) termite nutrient cycling, (vi) termite influence on hydrology, (vii) termite mound influence on plant species diversity and (viii) termite mound influence on large herbivores. Our review showed that African termites are diverse, with the potential to influence ecosystems heterogeneity through soil nutrients enrichment, which in turn influences forage abundance (thicket clumps), diversity and quality. High forage quality occurring on termite mounds influences herbivory patterns in the savanna ecosystem. Herbivory is reported to be higher on termite mounds compared to the expansive savanna landscape. The most common plant family occurring on termite mounds is Capparaceae. We suggest that future studies focus more on: (1) the influence of termite mounds on plant functional traits, (2) the importance of termite mounds in dryland savanna cropping/rangeland systems, and (3) on ways to support establishment of mound building termite species.
In this review, we have attempted to highlight the critical role which anthills could play in sustainable agriculture practices as a locally available resource for the benefit of financially and soil fertility challenged smallholder farmers. Examples from across sub-Saharan Africa region have been elucidated in this paper on how the anthills have been utilized as a choice of low external input farming strategy for soil fertility challenges. Data from the study was collected through literature search from past and present research work by various scientists across the globe encompassing the internet and research articles. We have become aware that anthill soils could play a crucial role as an alternative to chemical fertilizer for farmers who have no means of buying inorganics. We recommend that for effective utilization of anthills in crop production, there is need to build the capacity of extension staff and farmers on the application method using micro dosing techniques and simple estimation of quantity for determining the requirements per hectare. Raising awareness to policy makers at all levels could stimulate interest on how this resource could be integrated as one of the components of integrated soil fertility management in conservation agriculture technologies. Carrying out studies which would focus on factors that could help in fast development of anthills would be key for enhancing crop development amongst the smallholder farmers challenged by cost of fertilizer input.
Five highly efficient phosphate solubilizing bacteria, viz., Pantoea sp. A3, Pantoea sp. A34, Kosakonia sp. A37, Kosakonia sp. B7 and Bacillus sp. AH9 were isolated from termitorial soils of Sanjivani island of southern Maharashtra, India. These isolates were characterized and explored for phosphate solubilization and plant growth promotion. Among these, Bacillus sp. AH9 showed highest phosphate solubilization index (3.5) and solubilization efficiency (250%) on Pikovskaya agar. Interestingly, Pantoea sp. A34 displayed maximum mineral phosphate solubilization (1072.35 mg/L) in liquid medium and during this period the pH dropped to 3.13. All five isolates had highest P solubilization at 48 h after inoculation. During mineral phosphate solubilization, both gluconic acid and 2-keto gluconic acid were produced by Kosakonia and Bacillus isolates, while only 2-keto gluconic acid was detected in Pantoea isolates. Highest organic acid (39.07 ± 0.04 g/L) production was envisaged in Bacillus sp. AH9, while Pantoea sp. A34 produced the least amount (13.00 ± 0.01 g/L) of organic acid. Seed bacterization with Pantoea sp. A3 and Kosakonia sp. A37 resulted in ~ 37% and ~ 53% increase in root length of tomato seedlings, respectively, while Pantoea sp. A34 and Kosakonia sp. B7 had deleterious effects on root length as well as overall growth of the seedlings. To our knowledge, this is the first report of plant growth promoting potential of microorganisms isolated from termitorial soil of Sanjivani island, which is a drought-prone area. Therefore, such efficient growth promoting P solubilizers can offer an effective solution for sustainable agriculture in arid, dryland farming and drought-prone regions.
Heuweltjies are unique landscape features putatively created by the termite Microhodotermes viator through their burrowing and nest-building activities. They have been closely examined in the natural veld of the Western Cape in the recent past and are the focus of many ecological studies, but their effect in cultivated landscapes (e.g. vineyards and orchards) has remained unexplored. This study addresses the vigour and physiology of vines growing on and off heuweltjies, as well as the wine emanating from these vines. This study was conducted on Cabernet Sauvignon and Shiraz in two climatic regions of the Western Cape, namely Stellenbosch (Mediterranean climate) and Robertson (semi-arid climate) respectively, to better understand how differences in heuweltjie characteristics correspond to differences in rainfall and temperature. Through the use ofANOVAs and Fisher's LSD post hoc tests to indicate statistical significance, it was apparent that the soil on and off heuweltjies differed significantly in respect of several physical and chemical properties. Consequently, soil water content was more favourable on heuweltjies, especially in the Stellenbosch area, where only supplementary irrigation was applied. Heuweltjies induce substantial changes in grapevine vigour and grape composition. Differences in grapevine physiology between heuweltjie and non-heuweltjie plots were subtle, but vine vigour was severely altered on the heuweltjie-associated vines, exhibiting excessive vegetative growth in Stellenbosch and leading to variations in berry and wine characteristics on and off the heuweltjies. The opposite was observed in the semi-arid climate of Robertson. The presence of heuweltjies in vineyards presents an opportunity to produce and market wines with a difference in respect of their characteristics and unique origin.
The functional role of keystone species is considered by way of examples. The focus is on termites, beavers, and kangaroo rats.
While many animal species are acting as ‘ecosystem engineers’, the term ‘keystone species’ in its proper sense should be restricted to cases where ecosystem stability, structure, function and dynamics are determined by only one species. In so doing, numbers of ‘keystone species’ will be considerably reduced. The decline or extinction of a keystone species will be followed by fundamental changes of its habitat and biocoenosis. Related animal species influencing their habitats in a combined action (e.g.; kangaroo rats) have been called a ‘keystone species guild’.
Predation is a key determinant of prey community structure, but few studies have measured the effect of multiple predators on a highly diverse prey community. In this study, we asked whether the abundance, species richness, and species composition of a species-rich assemblage of termites in an Amazonian rain forest is more strongly associated with the density of predatory ants or with measures of vegetation, and soil texture and chemistry. We sampled termite assemblages with standardized hand-collecting in 30 transects arranged in a 5 km × 6 km grid in a terra firme Amazonian rain forest. For each transect, we also measured vegetation structure, soil texture, and soil phosphorus, and estimated the density of predatory ants from baits, pitfall traps, and Winkler samples. Seventy-nine termite species were recorded, and the total density of predatory ants was the strongest single predictor of local termite abundance (r = −0.66) and termite species richness (r = −0.44). In contrast, termite abundance and species richness were not strongly correlated with edaphic conditions (¦r¦ < 0.01), or with the density of non-predatory ants (rabund = −0.27; rs = −0.06). Termite species composition was correlated with soil phosphorus content (r = 0.79), clay content (r = −0.75), and tree density (r = −0.42). Assemblage patterns were consistent with the hypothesis that ants collectively behaved as generalist predators, reducing total termite abundance, and species richness. There was no evidence that ants behaved as keystone predators, or that any single termite species benefited from the reduction in the abundance of potential competitors.
To develop a better understanding of the physical properties and microstructures of the termite hill soils, we have carried out studies on the soil samples collected from two locations: near Dehradun, Utta-rakhand and near Hauz Khas, New Delhi. Their ele-mental composition and microstructure were studied using different instrumentation techniques, such as powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscope (TEM) and energy-dispersive analysis of X-ray (EDAX). α-Quartz (SiO2) was present in both the samples, while the sample collected from Hauz Khas, Delhi also con-tained β-cristobalite phase of SiO2. TEM-EDAX showed that termite hill soil consisted of silica (quartz), aluminium oxide, manganese oxide and iron oxide along with small percentage of potassium and calcium. Our studies highlight the potential to gene-rate α-quartz from all termite hills. It is also possible to obtain the less common β-cristobalite form of silica in certain termite mounds.
The intensive farming practices that have been developed over the past 60 years are based mainly on the use of chemical inputs such as fertilisers and pesticides, mechanical tillage and monoculture. The limitations of these methods are now clear: long-term degradation of soil fertility, impacts on the environment and human health, high consumption of fossil fuels, low efficiency of inputs and threats to food security in a context of climate change. Would farming practices that rely on the activation of ecological processes be an alternative to achieve a balance between high productivity and environmental preservation? While many studies suggest a positive relationship between soil biodiversity and ecosystem services, there is considerable debate on the form such agricultural systems should take. This study reviewed the state of current knowledge and identified aspects requiring further research to achieve the aim of sustainable intensification of agriculture. The following major points emerged:
(i)
Most studies focused on the evaluation of individual practices. However, changes in farmers’ cropping practices to take advantage of soil biodiversity services would need to manage not only the interactions between various practices but also the trade-off between the technical and socio economic constraints of cropping systems. Advances in agricultural system design approaches may help to ensure appropriate trade-offs.
(ii)
More attention should be given to drawing on knowledge from different sources: laboratory studies focusing on the ecological functions of soil biodiversity, experimental surveys on farmers’ fields to rank the farming practices and processes to be included in site-specific models, and on- station experiments to test hypotheses and acquire additional reference material.
(iii)
Whereas advances in technical and scientific knowledge provide an increasing number of relevant indicators for characterizing biodiversity and ecological functions, studies are rarely targeted at the development of indicators that are accessible to farmers or their technical advisors. The lack of indicators accessible to grassroots players for evaluating the impacts of their decisions on soil biodiversity remains a serious obstacle to the development of innovative agro-ecological systems.
Mounds of Amitermes laurensis and A. vitiosus in Queensland had higher levels of a range of plant nutrient and other elements than their surrounding surface soils. The distributions of organic matter and a number of these elements varied with position in the mound. -from Authors
The intestinal mucus of 3 tropical geophagous earthworm species showed clear interspecific variations. This secretion always consists in energetic and easily metabolisable compounds, which rapidly disappear during the gut transit, probably digested by the ingested microorganisms. -from English summary
Heterotermes aureus and Gnathamitermes perplexus are dominant factors in soil turnover, litter decomposition and nutrient cycling in the Sonoran Desert. Together they move c744 kg/ha of soil to the surface each year. They increase the clay content of surface soils by 21 kg/ha/yr by selectively bringing up soil richer in clay. They alter the pH from slightly acidic to basic, mainly by bringing lime to the surface. They enrich the soil with organic C, total N, Ca, Mg, K and Na as a result of digesting plant material and depositing feces and/or saliva in their workings at the surface. Both are general feeders, but their characteristic attacks on different sets of preferred litter components tend to be complementary. Nutrients released by Heterotermes may remain in its workings for months or years, while those of Gnathamitermes are released within weeks or months by the first heavy rains. -Authors
The particular biological activity of the termites influences humification processes in soil. The soil-feeding termite T. macrothorax incorporates its faeces into its mounds and creates an humiferous stratum with an increased amount of carbon and humic compounds around its nest. The fungus-growing termite M. mülleri, which deposits its faeces on the ground, depletes the surroundings in organic matter.
(1) The effects of burning and grazing of dry tropical Indian savanna on the level of available nutrient pools and microbial C, N and P were assessed. (2) The maximum amounts of available nutrients and microbial biomass occurred in the dry period and minimum in the wet period. (3) Burning and grazing increased inorganic N by 54% and 15-49%, respectively and also increased bicarbonate-extractable inorganic P by 35% and 27-32%, respectively. (4) Mean annual microbial C varied from 361 to 466-mu-g g-1, microbial N from 35 to 44-mu-g g-1 and microbial P from 16 to 23-mu-g g-1 dry soil. The mean annual microbial C, N and P were positively related to each other. (5) Burning increased microbial C by 18%, microbial N by 26% and microbial P by 35%, and grazing increased microbial C by 15-18%, microbial N by 14-23% and microbial P by 19-29%.
Progress of the Dumas and Kjeldahl procedures over the past century is reviewed. Many recent papers claim that various modifications of the standard Kjeldahl method enhance accuracy, precision, or speed, and reduce cost of analysis. Furthermore, several authors advocate use of Pyrex tubes heated in an aluminum block for digestion instead of traditional Kjeldahl flasks. A review of current semimicro-Kjeldahl methodology suggests that proceeding under the following conditions gives satisfactory results: sample size, 50–200 mg for plant material, 100–500 mg for soil; digestion acid, concentrated H2SO4; sample size ratio (mL/g) of 16:1 for soils and 22:1 for plant materials; digestion salt, minimum 0.33 g K2SO4 added/mL H2SO4; catalysts, add CuSO4 5H2O at rate of 10% (w/w) of K2SO4 added, HgO at 5% (w/w) of K2SO4, or add Se to K2SO4–CuSO4 5H2O mixtures at rate of 1% (w/w) K2SO4; digestion time, 1 and 3 h past clearing for plant materials and soils, respectively; pretreatments, use salicylic acid or reduced iron to recover nitrate from sample. Use of Pyrex tubes heated in an aluminum block appears suitable for digestions. Our results indicate that the 2 commercial tube digestion systems tested produce satisfactory recovery of total N from soils and plant materials. Ammonium in Kjeldahl digests may be quantitatively determined by distillationtitration, ammonia electrode, or colorimetric techniques.
The termite species which accumulate nutrients in the nest in greatest proportion was Trinervitermes geminatus, followed by Macrotermes bellicosus (royal chamber). The external walls of the nests of Macrotermes and Cubitermes present similar, although not very high, levels of nutrients. -from English summary
Paired samples of top soil and epigeal mounds of Procubitermes aburiensis and Cubitermes severus were taken. Procubitermes has more specialised soil requirements than Cubitermes. Carbon, N, K and P were concentrated in mounds, a characteristic of most termite artifacts derived from soil. Large increases in exchangeable K and available P (up to 76 times the soil levels) were attributed to the effects on ingested soil of the high pH regime characteristic of the soil-feeder hind-guts. -from Authors
Measurements were taken in 1983-1985 in two plots, one burned at the end of every dry season, another protected since 1982. The ecosystem shows a N-accumulation, particularly in burned savanna, where there is an increased N-input by organic matter decomposition and biological fixation by free-living and root associated organisms. An average of 40% of the necessary N for TNPP comes from internal plant recycling; the rest is taken up from soil. There is a net gain, because N-outputs by TNPP and leaching are less than N-inputs by rainfall, biological fixation and inorganic matter decomposition. This gain is higher in burned savanna. -from English summary
A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.
The productivity of many agricultural systems is determined by the quantity of inorganic P (Pi) made available through mineralisation of organic P (Po) during the growing season. Because of the adsorptive nature of the soil mineral fraction, any recently-mineralised Po may be rapidly partitioned to the solid phase. Attempts to quantify Po mineralisation, have been unsuccessful due to the difficulties in separating recently-released Pi from labile Pi forms already existing in the soil. We have investigated the use of an isotopic dilution technique to measure the increase of isotopically-exchangeable P with time (E(t)) in: (i) A short-term experiment (1–100 min) where there was only the physico-chemical process of exchange of solution 32P with 31P located on the solid phase; and (ii) an incubation experiment (0–51 d) where there were both physico-chemical and biological (immobilisation and mineralisation) processes. Although the E(t) values were obtained by different means (water- and resin-Pi extractions), the marked difference between both values during the 51 d experiment could not be completely explained by 32P exchange with 31P in the solid phase. The strong association between E(t) increment with Po and CO2 respiration values during incubation suggest biological participation. Estimates of Po mineralisation rates for the low P-sorbing soils (220–900 μg P kg−1 d−1) were similar to values in the literature that were obtained by isotopic and non-isotopic methods.
The dynamics of phosphorus in soils derived from different textured parent materials were studied. Soils weathered from the three parent materials were Haploborolls but different in texture and solum depth. Microbial phosphorus by hexanol fumigation, and mineralization rates of organic P (Po) were assessed with a 32P dilution technique and P was fractionated using a modification of the method of Hedley et al.Microbial P and Po mineralization rates were significantly affected by parent materials. The high rates of mineralization for the fine-textured soils correspond well with their higher content in substrates able to mineralize e.g. total carbon, Po and microbial Pi. The residual P (e.g. more stable Pi and Po forms) is the principal P fraction in the analyzed Mollisols.
The relationship between phosphatase activity and soil was studied in 14 mounds and adjacent control soils of plant debris-feeding termites from a Venezuelan savanna. The soils were assayed for acid phosphatase activity with p-nitrophenyl phosphate as substrate and for the effect of inorganic P (300 g P g–1). The proportion of organic matter in the mounds was four times that found in topsoils, indicating strong selection by the termites for organic-rich soil fractions. A comparison of phosphatase activities found no difference between mounds and adjacent soils. It seems possible that the expected increase of enzyme activity in mounds, due to a higher C content, was counteracted by enzyme inhibition due to higher levels of available inorganic P in the mounds. Addition of inorganic P to soil and mound material reduced enzyme activities by 10%–45%, but after a 2-day incubation period differences between the treated soil and the control tended to disappear.
The incidence of termite mounds was determined in twenty-six sites in the Trachypogon savannas at the Orinoco Llanos, including a wide range of physionomic types. A multiple discriminate analysis was utilized to analyze ecological variables as the best indicators of a given area's suitability for support of terrestrial Velocitermes and/or Nasutitermes species. The variables included physical attributes (texture, ineffective soil mass, water holding capacity, and infiltration rate), chemical attributes (cation exchange capacity, base saturation, and organic matter content), soil characteristics, and the above-ground phytomass accumulated at each stand. Results indicated that soil physical variables determining water balance during critical dry periods were of paramount value for the successful establishment of mound-building nasute termites in Trachypogon savannas.
The allocation of phosphorus (P) was studied in the different components of a Trachypogon savanna ecosystem, particularly in those related to biological productivity processes. The research was based on the sequential fractionation of soil P and on the determination of P content in different plant components. Soil is the principal reservoir of P (more than 99%), which is distributed mostly in forms of low availability. Microbial soil P represents about 6% of total P in this ecosystem, whereas cattle and vegetation accumulate about 1% P. The relatively high P content in microorganisms suggests the important role of this pool as a source of labile P and as a catalyzer of P transformations. Although available P forms are scarce, microorganisms and plants can satisfy their P requirements from the organic labile and moderately labile fractions, which account for 24% of total P in the soil.
Soil-feeding termites ingest humified, organic-rich soil. The soil faeces are used for nest construction and mounds of two species of Cubitermes contained more soil, clay, exchangeable Ca and Mg, available P, total N and organic C than adjacent topsoil. Available P increased by 1.4–6.0 times. Mounds of a plant-debris feeding termite, Trinervitermes, contained significantly more of these fractions, with the exception of available P, than adjacent topsoil. The modification of Trinervitermes mounds by Cubitermes resulted in a 2-fold increase in available P, whereas organic C remained the same and N increased by 1.5-times. The relatively large increase in available P resulting from soil feeding termites could be attributed to the high pH regime in their hind-guts.
A study about the competition between organic anions (oxalate and malate) - currently present in the rhizosphere and phosphate for adsorption sites in tropical soils - indicates that in the presence of organic anions, phosphate adsorption by soils is reduced. The extent of such reduction is dependent on the way in which either phosphate or the organic anion are added to the soil. The organic oxyanions studied are more rapidly adsorbed to the soil surface than the phosphate; consequently those anions, when existing in the rhizosphere, can improve the phosphate status of soil.
Changes in inorganic and organic phosphorus (P) fractions resulting from 65 years of cropping in a wheat‐wheat‐fallow rotation were studied using a sequential extraction technique. Total P content of the cultivated soil was 29% lower than that of the adjacent permanent pasture; the major loss of P (74% of total P lost) was organic P and residual P. Of the total P lost, 22% was from the extractable organic P forms, whereas 52% originated from stable P.
Incubation studies were used to study seasonal P transformations during simulated fallow with and without residue incorporation and P fertilization. Nine monthly additions of cellulose (765 µg C · g ⁻¹ soil) with and without P (9 µg · g ⁻¹ soil) significantly altered levels of total extractable organic P and inorganic P in incubated soils. Evidence is provided for microbial activity playing a major role in redistributing P into different forms in the soil.
Stimulation of total microbial activity (CO2 production), and soil organic nitrogen mineralization by the subterranean fungus-growing termite Ancistrotermes cavithorax was studied. Soil from the walls of the fungus comb chambers and control soil free from termite and root activities were sampled from the field and held at 28°C for 30 days. CO2. NH+4-N and NO−3-N production were regularly measured. NO3−-N production was negligible and only ammonification occurred. The more the soil has been worked by termites, the greater the amounts of CO2 and ammonia produced. This increased activity of microflora is probably related to the supply of energy-rich substrates by termites.
A range of gaseous, liquid and vapour biocides was tested in combination with seven extradants for their ability to release P from soil microorganisms in situ. The biocides tested were chloroform, ethanol, propan-1-ol, hexan-1-ol, β-propiolactone, formaldehyde, glutaraldehyde, ethylene oxide and methyl bromide. The extradants tested were 0.5 M NaHCO3 (pH 8.5), 0.1 M NaHCO3 (pH 8.5), 50 mM NaOH, 10 mM CaCl2, 50 mm H2SO4, 30 mm NH4F + 0.1 m HC1, and an anion exchange resin in the bicarbonate form suspended in distilled water. An incubation technique using 32P ensured that only microbial P was measured.Chloroform and hexanol were the most effective biocides: the latter is preferred because of its less hazardous nature. The best extradant was 0.5 M NaHCO3 (pH 8.5). Mixed populations of soil organisms were used for calibration, and the Kp factors obtained with hexanol and 0.5 m NaHCO3 (pH 8.5) were 0.33, 0.40 and 0.57 for the three soils studied.Since microflora differ from soil to soil, as do the amounts and form of P released, calibration is necessary for each soil. Incubation is not recommended as a prior treatment for samples used to measure biomass P: the soils should be treated with hexanol or extracted immediately after sampling to avoid quantitative or qualitative changes in the biota or biomass. Errors associated with the inclusion of roots in the sample can be minimized by removing the bulk of the roots before fumigation.
Humic acids (HAs) extracted from termite mounds constructed by two major species of Macrotermes (M. michaelseni and M. herus) and from surrounding soils in five ecological regions of Kenya were characterized by 13C NMR, IR spectroscopy, elemental analyses and optical measurements. Termite mounds had higher pHs, more clay but less sand and lower ratios than adjacent soils. Except for one site, HAs from termite mounds contained less C and more O than did HAs extracted from adjacent soils. ratios in all instances were lower for HAs from surrounding soils than for HAs from termite mounds, indicating that the molecular weights of the HAs for soils were higher than those of HAs from mounds. 13C NMR spectra of HAs showed major resonances at 115.2, 128.6 and 136.6 ppm (due to aromatic C) and at 175 ppm (C in CO2H groups). Oxygen-substituted C (including carbohydrates) decreased, whereas CO2H groups increased from the outer crust to nursery to the royal chamber of the mound. The distribution of C in HAs from different parts of termite mounds resembled that of HAs from adjacent soils except that soil HAs were less aromatic. Site appeared to affect the composition of HAs: HAs extracted from both mounds and soils at sites 2–5 were more aliphatic than HAs isolated from the mound and soil at site 1. In general, HAs from soils adjacent to termite mounds contained more CO2H groups. IR spectra did not show any significant differences between mound and adjacent soil HAs.
Twelve termite mounds and adjacent Ah and Ap horizons were sampled at three sites near Salisbury, Rhodesia. The mass of termite mounds occupied by M. falciger at one site was estimated at 620 t/ha, and contained the following amounts of nutrients expressed as percentages of the amounts in mounds and Ap horizon combined: extractable Ca 95%, mineral N 81% extractable K 69%, and available P 69%.
Pot experiments using perennial ryegrass gave higher dry matter yields from termite mounds than from the Ap and Ah horizons. Crop production could therefore be increased by mixing termite mounds with the soil.
We studied the sorption of phosphate and oxalate on a synthetic aluminium hydroxysulphate complex and the associated release of sulphate from this complex. In the pH range 4.0–9.0 the presence of phosphate or oxalate tended to increase the release of sulphate. Much more phosphate than oxalate was sorbed, but in most cases oxalate caused more removal of sulphate than did phosphate. Only in acid systems may these results be partly attributed to the greater solubilization of the complex in the presence of oxalate than in the presence of phosphate. At pH > 8.0 in the presence of phosphate, and at pH > 6.5 in the presence of oxalate, the quantities of sulphate replaced were greater than the quantities of phosphate or oxalate sorbed, suggesting that hydroxyl ions competed with phosphate and oxalate for sorption sites and sulphate removal. Sulphate was only partly removed from the complex even after repeated washings with phosphate or oxalate solutions or after 120 h in the presence of these ligands at pH 6.0. When phosphate and oxalate were added as a mixture much more phosphate than oxalate was retained. Phosphate strongly inhibited oxalate sorption, whereas oxalate partly prevented phosphate sorption only at pH < 7.0. More sulphate was removed in the presence of both the anions than in the presence of phosphate alone, but less than that desorbed in the presence of oxalate alone.
Nasutitermes ephratae are often abundant in seasonally flooded and dry Venezuelan savannas, where they play an important role in litter decomposition and nutrient cycling. Measurements were made of phosphorus forms and associated properties in 14 mounds and adjacent soils. Mounds contained on average over twice as much total phosphorus as adjacent soils. The difference was differentially distributed, mainly as inorganic forms. Mounds also display a relatively high organic matter content. ‘Available’ forms of P, especially water-soluble P, increased several times as a result of termite activity. Concomitantly, P-sorption was greatly reduced in mounds compared to surrounding soils.
Mounds did not display higher phosphatase activity. The elevated organic carbon content, high level of soluble P, together with very high C/P0 ratios found in mounds, probably inhibited phosphatase activity.
A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.RésuméUne méthode spectrophotométrique est décrite pour le dosage du phosphate dans l'eau de mer, an moyen de molybdate d'ammonium, en présence d'acide ascorbique et d'antimoinc. Il se forme rapidement un composé violet bleu, renfermant antimoine et phosphore dans un rapport atomique de 1:1.ZusammenfassungBeschreibung einer Methode zur Bestimmung von Phosphat in Mecrwasser mit Hilfe von Ammoniummolybdat in Gegenwart von Ascorbinsäure und Antimon. Der gebildete blau-violette Komplex wird spektrophotometrisch gemessen.
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Measurement of phos-phorus in the soil microbial biomass: a modi®ed procedure for ®eld soils A modi®ed single solution method for deter-mination of phosphates in natural waters
- M J Mclaughlin
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- Lo Âpez-Herna Ândez
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Le cycle de I'azote dans une savane a  Trachypogon
- Chaco Ân
- P Lamotte
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- P Chaco Ân
- M Lamotte
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- E Garnier-Sillam
- J Renoux
- F Toutain
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dans une savane a  Trachypogon au centre du Venezuela. Revue
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Environmental Protection Agency, 1971. Methods of Chemical Analysis of
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Garnier-Sillam, E., Renoux, J., Toutain, F., 1989. Les composes humiques
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Phosphatase activity in Nasutitermes ephratae termite nests
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- P Nannipieri
- J C Fardeau
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P-Isotopic exchange values in relation to Po mineralization in soils with very low P-sorbing capacities
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Le cycle de I’azote dans une savane á Trachypogon au centre du Venezuela
- Chacón
Phosphatase activity in Nasutitermes ephratae termite nests
- López-Hernández
Les mucus intestineaux de ver de terre moteur de leur interaction avec la microflore
- Martin