L.M. Condron

• Lincoln University

In 2016, a group of experts convened to set priorities for organic phosphorus (P) research, addressing global issues, methodological strengths and weaknesses, and the benefits of understanding the organic P cycle. Seven years later, scientists and students with an interest in organic P reconvened to discuss progress and new insights, and this revie...

To understand the effects of agricultural land use change and management on soil carbon (C) cycling, it is crucial to examine how these changes can influence microbial soil C cycling. Network analysis can offer insights into the structure, complexity, and stability of the soil microbiome in response to environmental disturbances, including land use...

Introduction In agroecosystems, phosphorus (P) applications over a long time have accumulated in soil as legacy P. This environmental challenge can be an agronomic opportunity as soil legacy P could be recovered in cropping systems using practices such as green manuring. We hypothesised that, at moderate soil available P levels, plant‐soil interact...

Greenhouse gas (GHG) emissions pose a challenge to the modern world and further generations. One possible strategy for climate change mitigation is enhancing soil carbon (C) sequestration by promoting C uptake from the atmosphere and storing it in the form of soil organic matter (SOM) to reduce increases in atmospheric carbon dioxide concentration....

Background The ancient kauri (Agathis australis) dominated forests of Aotearoa New Zealand are under threat from a multitude of ecological disturbances such as forest fragmentation, biodiversity loss, climate change, and the spread of the virulent soil pathogen Phytophthora agathidicida. Taking a wider ecosystem-level approach, our research aimed t...

As exotic plants invade into a new range, they can escape from specialist enemies. However, they may support generalist enemies, including both native and introduced fungal pathogens, which creates the potential for spillover and apparent competition from exotic to native plants in communities. To assess the potential for spillover of putatively pa...

Context Green manure crops have the potential to improve phosphorus (P) use efficiency in agroecosystems by enhancing the mobilisation of soil P reserves. Aims This study investigated and quantified the short-term mobilisation and uptake of soil P in the rhizosphere of several green manure crops. Methods Five plant species/varieties (Lupinus angu...

A defining feature of the Anthropocene is the distortion of the biosphere phosphorus (P) cycle. A relatively sudden acceleration of input fluxes without a concomitant increase in output fluxes has led to net accumulation of P in the terrestrial‐aquatic continuum. Over the past century, P has been mined from geological deposits to produce crop ferti...

Microbial community structure and function were assessed in the organic and upper mineral soil across a ~4000‐year dune‐based chronosequence at Big Bay, New Zealand, where total P declined and the proportional contribution of organic soil in the profile increased with time. We hypothesized that the organic and mineral soils would show divergent com...

The root-associated soil microbiome contributes immensely to support plant health and performance against abiotic and biotic stressors. Understanding the processes that shape microbial assembly in root-associated soils is of interest in microbial ecology and plant health research. In this study, 37 plant species were grown in the same soil mixture...

Phytophthora agathidicida is a virulent soil pathogen of Aotearoa New Zealand's iconic kauri tree species (Agathis australis (D. Don) Lindl.) and the primary causal agent of kauri dieback disease. To date, only a few control options are available to treat infected kauri that are expressing symptoms of dieback disease. Previous research has identifi...

Shallow subsurface pathways dominate dissolved reactive phosphorus (DRP) losses in grassland soils that are: poorly drained, shallow, or have a perched water table in wetter months causing saturation‐excess runoff. Saturated conditions can lead to anoxia, which can accelerate phosphorus (P) loss. Two scales of investigation were utilized in this st...

Afforestation of grassland is being promoted as a measure to mitigate climate change. While grassland afforestation influences the soil bacterial community structure and composition, the mechanisms involved and impacts of different tree species are poorly understood. In this study, we characterized the soil bacterial community to determine the phyl...

Dissolved reactive phosphorus (DRP) loss from agricultural soils can negatively affect water quality. Shallow subsurface pathways can dominate P losses in grassland soils, especially in wetter months when waterlogging is common. This study investigated the processes controlling intra- and inter-event and seasonal DRP losses from poorly drained perm...

Repeated phosphorus (P) inputs can lead to the accumulation of surplus P in soil with enhanced potential risk of transfer and accelerated eutrophication of aquatic environments. Intensive pork production in Rio Grande do Sul in southern Brazil results in the generation of large quantities of P-rich waste in the form of pig slurry, which is used to...

Purpose Legume establishment and persistence in New Zealand hill and high-country soils are largely limited by high soil acidity and associated aluminum (Al) toxicity. The present study aimed to evaluate the effect of four rates of phosphogypsum (0, 1, 3, and 9 t ha⁻¹) on Al speciation in the soil solution and to examine which species are mostly im...

Soil microbes and phosphatase enzymes play a critical role in organic soil phosphorus (P) cycling. However, how long‐term P inputs influence microbial P transformations and phosphatase enzyme activity under grazed pastures remain unclear. We collected top‐soil (0‐75 mm) from a grazed pasture receiving contrasting P inputs (control, 188 kg ha‐1 yr‐1...

The oomycete Phytophthora agathidicida is the causal agent of kauri dieback, which threatens the survival of endemic kauri (Agathis australis) forests in Aotearoa|New Zealand. Current chemical control of P. agathidicida involves the application of either a mixture of halogenated tertiary amines or phosphite salts with some success, but neither trea...

Streams can attenuate inputs of phosphorus (P) and therefore dampen the likelihood of ecosystem eutrophication. This P attenuation derives from many processes and remains poorly understood, particularly in reference to the geochemical mechanisms involved. We studied P attenuation in the form of (1) potential for mineral (co-)precipitation from the...

Nitrogen (N) and phosphorus (P) are critical to pasture productivity; however, limited information is available on how the single and combined additions of N and P affect soil P fractions and seasonal changes in microbial and biochemical processes linked to P cycling under pasture systems. A two-year field trial was conducted where N (0 or 250 kg h...

Purpose Increasing the pH of acid soils is a well-recognized means of improving their fertility; however, the effects that plants impose on rhizosphere soils in response to this change are not well understood. This research sought to investigate changes in phosphorus (P) availability in the rhizosphere of blue lupin (Lupinus angustifolius) in respo...

Nitrous oxide (N2O) is a greenhouse gas emitted from grazed pasture systems. The influence of phosphorus (P) fertility on these emissions is not understood. This study examined if fertiliser P affected N2O emissions following nitrate application to soil from the Winchmore long-term P fertiliser trial. We hypothesised increasing P fertility would en...

Context Soils irrigated with wastewater are generally phosphorus (P)-enriched. P losses from these soils may impair surface water quality. However, wastewater applications also alter soil pH and P availability. Aims We investigated if amending soils with aluminium (Al), iron (Fe) or calcium (Ca) sorbents could decrease the potential for P losses d...

The impact of soil water repellency (SWR) on soil phosphorus (P) mobility in surface water runoff remains contentious. Although SWR may cause a significant increase in surface runoff, especially in post-summer rainfall events, whether it contributes to background phosphorus losses remains unclear. Surface runoff and P concentrations in runoff were...

Phosphorus (P) loss from agricultural soils can negatively affect water quality. Models and management to decrease losses increasingly focus on P that is available and transported from areas in the landscape that are regularly saturated – and periodically anaerobic. Current models use soil tests conducted in oxic conditions, which do not represent...

Phytophthora agathidicida is a highly virulent pathogen of kauri (Agathis australis) and the causal agent of dieback disease in New Zealand’s kauri forests. This study aimed to identify microbial isolates isolated from kauri forest soils that inhibited the growth of P. agathidicida. Three different forms of in vitro bioassays were used to assess th...

While grassland afforestation can enhance the net mineralization of soil organic phosphorus (P), the mechanisms involved and impacts of different tree species are not clear. Soil samples were taken from replicated adjacent field plots that had been maintained under unfertilized grazed grassland, radiata pine (Pinus radiata), and eucalyptus (Eucalyp...

Liming effects on soil phosphorus (P) availability via biological P cycling are not clear. We conducted an 18-month field experiment on a long-term (60 years +) permanent fertilized grassland in a relatively dry environment. The aim was to examine the impact of liming on P biochemical processes and dynamics. Lime was applied at the beginning of the...

In soils with a fragipan or poor permeability, water may remain in a soil profile long enough to make it anoxic and reductive. The reductive dissolution of iron (Fe)‐ and manganese (Mn)‐oxides can release associated phosphorus (P). Therefore, the dissolved P would be vulnerable to subsurface flow and could contaminate nearby streams. It was hypothe...

New Zealand's ancient kauri (Agathis australis) forests are under threat from the spread of dieback disease, caused by the soil‐borne pathogen Phytophthora agathidicida. Characterizing the response of the soil microbiota to the infection of kauri with P. agathidicida is essential to identify how they may form a protective response to pathogen invas...

The biochemical drivers of phosphorus (P) availability and cycling are sensitive to changes in soil pH. However, reports of lime-induced pH modification effects on P availability are (1) inconsistent, (2) focused mainly on chemical changes, and (3) often limited to the bulk soil. Using lupin as an indicator species, we aimed to evaluate the effects...

Soil fertility remains a limitation to pasture production in the South Island high country of New Zealand, despite a strong history of aerial superphosphate fertiliser applications. This may in part be due to the acidic nature of these soils. This study of extensively farmed high country soils (n = 19) aimed to investigate the current status of soi...

Phosphorus (P) pollution of surface waters remains a challenge for protecting and improving water quality. Central to the challenge is understanding what regulates P concentrations in streams. This quantitative review synthesizes the literature on a major control of P concentrations in streams at baseflow—the sediment P buffer—to better understand...

A wide variety of soil phosphorus (P) fractionation schemes have been developed and used extensively for over 60 years, however, most are laborious and provide limited information on key parameters such as P mobility and adsorption. We propose an alternative multi-stage extraction technique that it is possible to complete in one day. This involves...

Ruminant urine patches in grazed grasslands significantly change the chemical and biological properties of the affected soils due to the predominance of urea within ruminant urine and the high rates deposited onto pastures. The net result is the loss of reactive N (Nr) but little is known about the gross N transformation rates leading to Nr losses...

The Haast chronosequence in New Zealand is a ∼6500-year dune formation series, characterized by rapid podzol development, phosphorus (P) depletion, and a decline in aboveground biomass. We examined bacterial and fungal community composition within mineral soil fractions using amplicon-based high-throughput sequencing (Illumina MiSeq). We targeted b...

The biodiversity in soil ecosystems is simultaneously incredibly rich and poorly described. In countries such as New Zealand, where high endemism in plant species emerged following extended geographical isolation, it is likely similar evolutionary pressures extended to soil microbial communities (our biodiversity ‘dark matter’). However, we have li...

Multispecies grasslands can alter nitrogen (N) cycling processes. A mesocosm experiment was performed comparing bare soil, soil planted with perennial ryegrass (Lolium perenne), white clover (Trifolium repens), plantain (Plantago lanceolata), and a mixed sward with all three species. We aimed to assess the plant effects on: ruminant urine-induced d...

Elevated atmospheric carbon dioxide (eCO2) associated with climate change increases plant production and soil nutrient transformations. However, changes in soil phosphorus (P) availability and dynamics are unclear. We used the long-term New Zealand Free Air CO2 Enrichment (FACE) experiment to quantify changes in P availability and soil P fractions...

Soil water repellency (SWR) is a natural phenomenon occurring in soils throughout the world, which impacts upon ecosystem services at multiple temporal and spatial scales (nano to ecosystem scale). In pastures, the development of SWR is primarily determined by the cycling of hydrophobic materials at the soil surface, and is controlled by climate, s...

Benthic stream sediments interact strongly with phosphorus (P) and can buffer dissolved reactive P (DRP) concentrations. The sediment P buffer can be measured with the sediment equilibrium phosphate concentration at net zero sorption (EPC0), which often correlates well with DRP. Yet, it is unclear how much of this P affinity in sediments is attribu...

Reducing nitrogen (N) input can improve crop productivity in cereal-legume intercrops, but the impact on phosphorus (P) acquisition is unclear. A 10-year (2009–2018) field experiment was conducted to quantify how P acquisition by sugarcane (Saccharum officinarum) was affected by intercropping with soybean (Glycine max (L.) Merrill at 1:1 and 1:2) w...

Rhizosphere processes play a critical role in phosphorus (P) acquisition by plants and microbes, especially under P-limited conditions. Here, we investigated the impacts of nutrient addition and plant species on plant growth, rhizosphere processes, and soil P dynamics. In a glasshouse experiment, blue lupin (Lupinus angustifolius), white clover (Tr...

In this work, we modelled the response of soil water repellency (SWR) persistence to the decrease in moisture in drying soils, and we explored the implication of soil particle size distribution and specific surface area on the SWR severity and persistence. A new equation for the relationship between SWR persistence and soil moisture (θ) is describe...

Legumes play critical dual roles in grazed grassland ecosystems; providing nitrogen inputs and high-quality feed for grazing livestock. However, many species fail to persist in acidic, low fertility soils. A glasshouse study was conducted to investigate the response of lucerne (Medicago sativa) to phosphogypsum (PG), lime and soluble P + S fertiliz...

Organic forms of phosphorus (P) account for over half of the total P present in most soils and make a significant contribution to P cycling and plant nutrition through the actions of various plant and microbial phosphatase enzymes. However, not much is known about the bacterial communities harbouring phosphatase genes, either in composition, abunda...

Exotic plants reduce carbon sequestration Invasive exotic plants have become a major problem worldwide, with transformational effects on the composition and function of ecosystems. In a multifactorial experiment in New Zealand, Waller et al. show that exotic plants accelerate carbon loss from soils through their interactions with invertebrate herbi...

Ecosystem process rates typically increase after plant invasion, but the extent to which this is driven by (i) changes in productivity, (ii) exotic species' traits, or (iii) novel (non-coevolved) biotic interactions has never been quantified. We created communities varying in exotic plant dominance, plant traits, soil biota, and invertebrate herbiv...

Globally, the conversion of primary forests to plantations and agricultural landscapes is a common land use change. Kauri (Agathis australis) is one of the most heavily impacted indigenous tree species of New Zealand with less than 1% of primary forest remaining as fragments adjacent to pastoral farming and exotic forest plantations. By contrasting...

Andisols, rich in minerals like allophane, imogolite and iron- (Fe) or aluminum- (Al) oxides have high phosphorus (P) sorption capacity and require annual P additions to ensure plant productivity. It is known that the use of composted poultry manure (PM) increases soil labile P and carbon concentration, although the mechanisms controlling P availab...

A complex combination of environmental, biological, chemical, and physical properties and processes determine soil biodiversity and its relationship to biogeochemical functions and ecosystem services. Vegetation, land-use, and land management, in turn, influence diversity and function in the soil ecosystem. The objective of this review was to asses...

Abstract. Streams can attenuate inputs of phosphorus (P) and, therefore the likelihood of ecosystem eutrophication. This attenuation is, however, poorly understood, particularly in reference to the geochemical mechanisms involved. In our study, we measured P attenuation mechanisms in the form of (1) mineral (co-)precipitation from the water-column...

Ruminant urine patches on grazed grassland are a significant source of agricultural nitrous oxide (N2O) emissions. Of the many biotic and abiotic N2O production mechanisms initiated following urine-urea deposition, codenitrification resulting in the formation of hybrid N2O, is one of the least understood. Codenitrification forms hybrid N2O via biot...

Formation of mineral-organic associations is a key process in the global carbon cycle. Recent concepts propose litter quality-controlled microbial assimilation and direct sorption processes as main factors in transferring carbon from plant litter into mineral-organic associations. We explored the pathways of the formation of mineral-associated orga...

Improving the efficiency of phosphorus (P) use is a major challenge for agricultural production and sustainability. Using a combination of new and historic data, a mass balance approach was employed to construct and discuss a comprehensive P budget under temperate irrigated grazed pasture that had received different inputs of superphosphate fertili...

The microbiome of grassland soils provides ecosystem services essential to plant health and productivity, including nutrient cycling and suppression of soil-borne diseases. Understanding how soil management practices affect soil microbial communities will provide opportunities by which indigenous soil microbes and their functions can be managed to...

Purpose Stream sediment can control phosphorus (P) in the water column at baseflow. Two common laboratory analyses of sediment P are the equilibrium phosphate concentration at net zero sorption (EPC0) and P fractionation. Good sample handling ensures representative results, but oftentimes, studies rely on air-dried or freeze-dried samples, which al...

Soils are the main source of nitrous oxide (N 2 O) emissions, with 60–70% of global N 2 O production due to the enhanced denitrification activity with elevated nitrogen (N) availability associated with agricultural intensification. The amendment of agricultural soils with biosolids, the residual product of wastewater treatment, has been used for se...

Phosphorus (P) is an essential nutrient for life. Deficits in soil P reduce primary production and alter biodiversity.A soil P paradigm based on studies of soils that form on flat topography, where erosion rates are minimal,indicates P is supplied to soil mainly as apatite from the underlying parent material and over time is lost viaweathering or tra...

Aims We assessed and quantified the cumulative impact of 20 years of biomass management on the nature and bioavailability of soil phosphorus (P) accumulated from antecedent fertiliser inputs. Methods Soil (0–2.5, 2.5–5, 5–10 cm) and plant samples were taken from replicate plots in a grassland field experiment maintained for 20 years under contrast...

The article “Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities”, written by Timothy S George et al., was originally published with incorrect affiliation information for one of the co-authors, E. Klumpp.

In the original article, Fig. 3 was mistakenly replaced by a copy of Fig. 2. The correct version of Fig. 3 is published here.

Cropping soils vary in extent of natural suppression of soil-borne plant diseases. However, it is unknown whether similar variation occurs across pastoral agricultural systems. We examined soil microbial community properties known to be associated with disease suppression across 50 pastoral fields varying in management intensity. The composition an...

PCR primers and thermocycling conditions used for assessing the structure and size of total bacterial and Pseudomonas communities in soil DNA. (DOCX)

GeoChip 5.0: Probes that provide coverage of genes with a putative role in the suppression of soil-borne plant pathogens. (XLSX)

Influence of soil type and land use on microbial community structure. (DOCX)

Total bacteria (T-RFLP) OTU data. (XLSX)

Physico-chemical and environmental properties of 50 New Zealand pasture soils. (XLSX)

Pseudomonas (DGGE) OTU data. (XLSX)

Individual step-wise regression models for each disease suppressive gene/gene category. (DOCX)

The objective of this study was to quantify the combined effects of long-term plant biomass retention/removal and environmental conditions on soil microbial biomass phosphorus (P), bioavailable P, and acid phosphomonoesterase activity. Topsoil samples (0–2.5 and 2.5–5 cm) were collected from replicate field-based plots that had been maintained unde...

A correction has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Background and aims Soil development follows a predictable pattern of nutrient availability over hundreds to thousands of years, which drives changes in the composition and productivity of associated plant communities. However, our understanding of the influence of soil forming factors such as parent material on ecosystem development is constrained...

In the coming decades there will be increasing pressure on global food systems, and agriculture will have the challenge to provide food security for a growing world population without impacting environmental security. Accordingly, it will be necessary to use modern technologies in agroecosystems in order to supply sufficient food and decrease the n...

The effect of 62 years of different irrigation regimes on the amounts, forms and distribution of phosphorus (P) in the soil profile to 100 cm under grazed pasture was determined. Irrigation treatments included nil irrigation (base average rainfall of 740 mm year⁻¹; control), together with flood irrigation applied when gravimetric moisture (GM) in t...

Zymographic methods for the 2D distribution of phosphatase activity in soils have markedly advanced our understanding of root-soil-microbiota interactions. Robust quantitative approaches for 2D assays, which use 4-methylubelliferyl phosphate (4-MUP), are needed to advance a mechanistic understanding of enzyme behaviour and distribution in soils. We...

Aims Soil organic nitrogen (N) turnover is significantly influenced by elevated N deposition, precipitation and human-caused disturbances, but the underlying mechanism remains unclear. Identifying the relationships among the soil organic N fractions and N-mineralizing enzymes activities may advance our knowledge of the dynamics of soil organic N....

The soil organic matter (OM) content of soils in a long-term fertiliser field trial (Winchmore, New Zealand) are similar (P > 0.05) despite >60 years application of different phosphorus (P) rates. As the net primary productivity increased with P addition, greater losses of carbon (C) occur concomitantly with increased P fertility. Several hypothese...

Intensively managed agricultural pastures contribute to N2O and N2 fluxes resulting in detrimental environmental outcomes and poor N use efficiency, respectively. Besides nitrification, nitrifier-denitrification and heterotrophic denitrification, alternative pathways such as codenitrification also contribute to emissions under ruminant urine-affect...

Weathering of primary silicates to secondary clay minerals over time affects multiple soil functions such as the accumulation of organic matter and nutrient cations. However, the extent of clay mineral (trans)formation as a function of soil development is poorly understood. In this study, the degree of weathering of sediments along a 120 kyr soil f...

Chronosequences can provide valuable insights into carbon (C) and nitrogen (N) dynamics across natural gradients with C and N stable isotopes serving as powerful tool investigating these dynamics. We studied changes in δ13C and δ15N values in litter, organic layer and mineral soil on dunes across the Haast chronosequence (New Zealand), which spans...

Management of soil biological resources to optimise plant production, efficiency of nutrient inputs, and system sustainability is an emerging opportunity for pastoral agriculture. To achieve these goals, suitable tools that can assess the functional state of the soil ecosystem must be developed and standardised approaches to their application adopt...

Long-term soil and ecosystem development involves predictable changes in nitrogen (N) and phosphorus (P) availability and limitation, but far less is known about comparable changes in sulfur (S) despite its importance as an essential plant macronutrient and component of soil organic matter. We used a combination of elemental analysis, X-ray absorpt...

Andisols are characterized by a high phosphorus (P) fixation capacity, which is a limiting factor for plant production. Continuous application of P fertilizer may result in an accumulation of P associated with soil organic matter (SOM), which further acts to reduce the availability of the added P. The objectives of this study were (1) to evaluate t...