ThesisPDF Available

DIVERSITY AND ABUNDANCE OF DUNG BEETLES ACROSS DIFFERENT LAND USE TYPES AND THEIR ROLE IN SOIL FERTILITY IMPROVEMENT IN KENYA

Authors:
A preview of the PDF is not available
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
Low soybean yields in western Kenya have been attributed to low soil fertility despite much work done on nitrogen (N) and phosphorus (P) nutrition leading to suspicion of other nutrient limitations. To investigate this, a nutrient omission trial was set up in the greenhouse at the University of Eldoret-Kenya to diagnose the nutrients limiting soybean production in Acrisols from Masaba central and Butere sub-Counties, and Ferralsols from Kakamega (Shikhulu and Khwisero sub-locations) and Butula sub-Counties and to assess the effect of liming on soil pH and soybean growth. The experiment was laid out in a completely randomized design with ten treatments viz; positive control (complete), negative control (distilled water), complete with lime, complete with N, minus macronutrients P, potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S) and with, micro-nutrients boron (B), molybdenum (Mo), manganese (Mn), copper (Cu) and zinc (Zn) omitted. Visual deficiency symptoms observed included interveinal leaf yellowing in Mg omission and N addition and dark green leaves in P omission. Nutrients omission resulted in their significantly low concentration in plant tissues than the complete treatment. Significantly (P 0.05) lower shoot dry weights (SDWs) than the complete treatment were obtained in different treatments; omission of K and Mg in Masaba and Shikhulu, Mg in Khwisero, K in Butere and, P, Mg and K in Butula. Nitrogen significantly improved SDWs in soils from Kakamega and Butula. Liming significantly raised soil pH by 9, 13 and 11% from 4.65, 4.91 and 4.99 in soils from Masaba, Butere and Butula respectively and soybean SDWs in soils from Butere. The results show that, poor soybean growth was due to K, Mg and P limitation and low pH in some soils. The results also signify necessity of application of small quantities of N for initial soybean use.
Article
Full-text available
Deficiencies of secondary and micronutrients (SMNs) are major causes of low maize yields in poorly responsive soils. This phenomenon minimizes the agronomic efficiency of N, P and K fertilizers and consequently result in a dwindling economic benefit associated with their use. Therefore, 18 on-farm trials were conducted in western Kenya during two cropping seasons to assess maize response to three NPK amendments; (i) N, P, K, Ca, Zn and Cu (inorganic and organic); (ii) N, P, K, Ca, Zn and Cu (inorganic) and (iii) N, P K, Zn and Cu (inorganic) and evaluate the profitability of their use compared to additions of only N, P and K fertilizers. In this set of experiments, maize response to any amendment refers to a yield increase of ≥2 t ha−1 above control and could be categorized in three clusters. Cluster 1, comprising of nine sites, maize responded to all amendments. Cluster 2, holding six sites, maize responded only to one amendment, N, P, K, Ca, Zn and Cu (inorganic). In this cluster, (2), emerging S, Mg and Cu deficiencies may still limit maize production. Cluster 3; consisting of three sites, maize responded poorly to all amendments due to relatively high soil fertility (≥17 mg P kg−1). Profitability of using NPK amendments is limited to Cluster 1 and 2 and the largest Value Cost Ratio (VCR) of 3.1 is attainable only when soil available P is below 4.72 mg kg−1. These variable responses indicate the need for developing site-specific fertilizer recommendations for improved maize production and profitability of fertilizer use in poorly responsive soils.
Book
Full-text available
Two sampling protocols for dung beetles are presented which are suitable for different approaches relying on quantitative data. The protocol for ecological assemblage studies uses standard-sized dung pats put directly on the ground to simulate natural conditions. It enables us to record the actual users of a resource only by allowing tourists (temporary visitors) to leave. The other protocol is a rapid method suitable for RBAs (Rapid Biodiversity Assessments) and uses pitfall traps with suspended bait. ___________________________________________________________________________ Dung beetles are becoming an increasingly important focal taxon for ecological and conservation studies (Spector 2006). Taking advantage of the easy attraction of dung beetles by suitable baits (faeces, carrion, other rotting matter), baited pitfall traps are commonly used for experiments with a variety of scopes, disregarding the fact that traps catch all specimens that approach the bait in a way allowing them to fall into the trap. Many Aphodiinae species seem to avoid traps by not landing in the trap whereas Scarabaeinae generally tumble into traps. Specimens of both groups might approach a resource but not use it (tourists). Trapped in the trap, tourists cannot be separated from actual users. Here two different protocols are proposed for two different approaches, written for novices to the field. Protocol 1 is suitable for dung beetle assemblage studies, focusing on recording the actual users of a resource. Protocol 2 is suitable for assessing the local species pool and species abundances of a study site (RBA – Rapid Biodiversity Assessment).
Article
Full-text available
Soil macrofauna contribute to key soil functions underpinning soil-mediated ecosystem services. There is limited understanding about the role of trees as ‘resource islands’ for soil macrofauna in agricultural landscapes and how this interaction is affected by soil degradation status. The study assessed the spatial influence of three dominant trees namely, Croton megalocarpus, Eucalyptus grandis and Zanthoxylum gilletii, on soil macrofauna abundance, along a soil degradation gradient resulting from continuous cultivation for 10, 16 and 62 years. It was hypothesised that spatial variation in soil macrofauna abundance is affected by duration of cultivation, tree species and distance from the tree trunk. Soils cultivated for 10 years showed highest soil nutrient levels. Notably, soil C and N were higher below the canopy of C. megalocarpus (64.6 g kg⁻¹ C; 6.7 g kg⁻¹ N), than E. grandis (58.7 g kg⁻¹ C; 5.9 g kg⁻¹ N) and Z. gilletii (54.5 g kg⁻¹ C; 5.6 g kg⁻¹ N) after 10 years of cultivation. Similar trends were also found after 16 and 62 years of cultivation, although the mean values for the two elements were below 40.0 g kg⁻¹ and 4.0 g kg⁻¹, respectively. Higher soil macrofauna abundance was found after 16 and 62 years of cultivation, though this was dependent on tree species and soil macrofauna group. Earthworm abundance was highest below the canopy of Z. gilletii averaging 389 individuals and 160 individuals m⁻², respectively, compared to 14 individuals m⁻² after 10 years of cultivation. Conversely, beetles showed higher numbers under E. grandis and C. megalocarpus than under Z. gilletii. Highest numbers of termites and centipedes were found under E. grandis after 16 years of cultivation. These findings support the importance of a diverse tree cover in agricultural landscapes to conserve soil macrofauna communities and the contribution of their activity to soil ecological functions.
Article
Full-text available
Knowing the biodiversity of dung beetles in agricultural and livestock environments is the basis for understanding the contribution that these organisms make in nutrient cycling and ecosystem functions. The aim of the present study was to investigate the structure of copronecrophagous dung beetle communities inhabiting the main agroecosystems in southern Brazil and correlate the presence of these organisms with soil properties. From December 2012 to April 2013, samples of dung beetles were taken in the municipality of Tubarão, Santa Catarina, Brazil (28° 28’ S; 48° 56’ W) in corn, bean, and sugarcane crops, and in cattle pastures. Beetles were captured in 16 sampling sites, four from each agroecosystem, following a standardized methodology: 10 baited pitfall traps (feces and rotting meat) at a spacing of 50 m with exposure for 48 h. The beetles were identified, weighed, and measured. Soil analyses were performed in order to correlate data on organic matter, texture, macro and micronutrients, and pH with data on the abundance of beetle species using canonical correspondence analysis. A total of 110 individuals belonging to 10 species of dung beetles was found. Twenty-four individuals from seven species (with total biomass of 2.4 g) were found in the corn crop; five individuals from three species (1.8 g) were found in the bean crop; 81 individuals from nine species (30.3 g) were found in cattle pasture areas; and lastly, there were no dung beetles recorded in the sugarcane crop. In areas of cattle grazing, the tunnelers Dichotomius nisus and Trichillum externepunctatum correlated positively with organic matter content, whereas the roller species Canthon chalybaeus correlated positively with soil texture, preferring sandier soils. In corn crop areas, D. nisus was again correlated with organic matter content. Paracoprid dung beetle species were correlated with organic matter content in the soil, and species belonging to the roller functional group were associated with soil texture in the corn crop, preferring sandy soils. Information regarding the relationship of dung beetles with physical-chemical soil properties may be an important strategy for increasing fertility and management of soil conservation in agroecosystems.
Article
A poor response to fertilizer application is one of the persisting constraints preventing closure of the maize yield gaps in Sub-Saharan Africa (SSA). It is speculated that nutrient imbalances derived from deficient and/or excessive concentrations could be one of the causes of this limited response of maize to fertilizer. This is however not confirmed and the extent of such poor response is ill-documented. To investigate this, we conducted 44 on-farm trials with a two treatment structure (with and without NPK fertilizer) in two subsequent seasons, the 2014 long rains (LR) and short rains (SR) distributed across two sites: Bungoma-Southwest and Busia-North in western Kenya. As a discriminating criterion between responsive and poorly responsive soils, we used a Value Cost Ratio (VCR) of 2 of NPK fertilizer use. Nutrient sufficiency ranges were developed using compositional nutrient diagnosis (CND method) and then used to identify both deficient and/or excessive nutrient concentrations occurring in maize grown in the poorly responsive soils. Results show that 48% of all fields from both sites could be classified as ‘poorly responsive’, with small VCR values ranging between 0.1 and 1.99. Nutrient deficiencies were more prevalent than situations of excessive concentrations in such fields. N-deficiency was the most common in the unfertilized (control) plots occurring in between 80 and 89% of the poorly responsive plots. Zn-deficiency became apparent in the fertilized plots and was observed at similar frequencies in this treatment. The next most widespread nutrient deficiencies in poorly responsive soils were those of P and Cu affecting between 70 and 79% of both control and fertilized plots. K and Mg deficiencies were rare in both treatments. This study indicates that the occurrence of poorly responsive soils in Bungoma-southwest and Busia-North is likely related to micronutrient deficiencies. These findings necessitate further investigation on the bioavailability of these micronutrients nutrients in such soils and a validation trial to evaluate the extent of crop responses.
Article
Soil fauna abundance and diversity and organic matter content are key indicators for the rate of soil degradation in Mediterranean-type ecosystems. The soil macrofauna populations were examined in three orange (Citrus sinensis) orchards and one persimmon (Diospyros kaki) orchard, with the same soil type and different management systems, to establish whether organic management benefits soil fauna and soil quality and what is the effect of flood irrigation. Vegetation cover, soil organic matter, bulk density and moisture were measured at each experimental site within the Canyoles watershed in Eastern Spain in summer of 2015. Earthworm abundance was highest at the organic orchard with flood irrigation, followed by the organic orchard with drip irrigation, with juvenile endogeic earthworms being the dominant group. Soil isopoda was the dominant group of the arthropod macrofauna, with highest abundance in the drip-irrigated organic orchard. Earthworm presence was highest in the flood-irrigated orchard, whereas soil arthropoda abundance was highest at the drip-irrigated organic site, where a thick litter layer was present. The soil organic matter was higher and soil bulk density lower at the organic orchards sites compared to conventional ones. The results suggested that organic farming was beneficial for soil biological activity, though the conversion from flood to drip irrigation can have a negative impact on earthworms, which may cause a decrease in infiltration capacity of the soil.