This 3.5-year grazed farmlet study investigated the impacts of regenerative agriculture and soil phosphorus (P) fertiliser on herbage dry matter (DM) yield and botanical composition in sheep-grazed dryland pastures. Four treatments compared regenerative with conventional agriculture, under high and low P fertiliser, with Olsen P targets of 10 and 20 mg P kg(-1). The regenerative system utilised a 12-species diverse pasture mix with short-duration grazing and long recovery periods, whereas conventional featured a lucerne (Medicago sativa L.) monoculture with best-practice grazing. In Year 1, conventional yield outperformed regenerative by 3 t DM ha(-1) (p < 0.01). However, in Years 2 and 3, yields were similar across all treatments, averaging 7.7 t DM ha(-1) in Year 2 and 10.3 t DM ha(-1) in Year 3. Fertiliser had a minor effect, with high-P treatments yielding 796 kg DM ha(-1) more than low-P (p < 0.01), regardless of management system. In the regenerative treatment, legume content dropped from 34% in spring 2022 to 17% in autumn 2025, while sown grass content increased from 9.5% to 63% over the same period. Unsown species (weeds) contributed more to total herbage DM in conventional than regenerative (p < 0.001), while the proportion of dead material was greater in regenerative (p < 0.001). Overall, regenerative matched conventional herbage yield in Years 2 and 3 but showed declining pasture quality due to reduced legume presence. Phosphorus fertiliser had a limited impact on yield and further research is required on how regenerative practices influence P dynamics in dryland pasture soils.

Grassland management practices can disrupt the stoichiometric balance between available soil nutrients and microbial communities, thereby impacting ecosystem functioning. Using a long-term field trial, we investigated the effects of four contrasting mowing treatments with/without nitrogen (N) addition on the elemental concentrations and stoichiometries of soil, plant, and microbial biomass. Retaining biomass after mowing resulted in lower C:N and C:P in plant shoots (C:N = 18.8, C:P = 283.9) compared with never mowing (C:N = 24.5, C: P = 493.4). Similarly, the mean soil available C:N when retaining biomass after mowing (C:N = 2.68) was lower than the ratio in the never mown grassland (C:N = 3.44). Removing biomass after mowing strongly depleted soil available phosphorus (P) concentration, leading to significantly higher C:P (C:P = 16.10) than that in the never mown grassland (C:P = 3.85). There were no significant differences in soil available carbon (C) concentration among the treatments, indicating that shifts in the C:N and C:P ratios of available resources were largely due to differences in nutrient rather than C availability. Despite differences in the stoichiometry of available resources, microbial biomass C:N and C:P was similar among treatments and consistently higher than those for the available substrates. This indicates that soil microbes were unresponsive to varying nutrient availability across treatments, suggesting they may be C-rather than nutrient-limited. In this long-term trial, microbial stoichiometry was resilient to soil P depletion and insensitive to N addition. The components of agroecosystems (plants, soil, and soil microorganisms) can contrast in their stoichiometries. Managing one component's nutrient limitation may have little influence with that of the other components.

Regenerative agriculture is a global movement aimed at improving agricultural sustainability by prioritising soil health and function. A key component of soil function is soil microbial activity, which underpins pasture productivity and nutrient use efficiency through the cycling of carbon (C), nitrogen (N) and/or phosphorus (P). The microbial community is highly sensitive to management change; however, soil extracellular enzyme responses remain poorly quantified in regenerative pasture systems. We compared regenerative and conventional system effects on soil extracellular enzyme activity in a dryland grazed farmlet experiment. The regenerative system comprised a 12-species diverse pasture mix with short grazing periods and extended recovery, while the conventional system used best-practice grazing of Medicago sativa L. Both systems also included high and low soil P fertility treatments. In each system, activities of eight soil extracellular enzymes were measured in spring and autumn over two years from October 2023 to April 2025. After 3.5 years (autumn 2025), regenerative management increased several extracellular enzyme activities compared with conventional lucerne pasture: beta-xylosidase (+66%; P < 0.0001), beta-1,-4-N acetylglucosaminidase (+53%; P < 0.0001), beta-glucosidase (+31%; P < 0.0001) and acid phosphatase (+21%; P = 0.01). In contrast, enzyme activity showed a limited response to soil P fertility. Enzymatic stoichiometric ratios indicated increased investment in P and C acquisition relative to N acquisition, suggesting persistent microbial P and C demand. These results indicate that regenerative pasture management can influence microbial activity and nutrient cycling, as well as challenge the assumption that elevated measures of soil labile P (Olsen P) alone alleviates microbial P demand in grazed grassland soils.

Context or problem: The efficiency of phosphorus (P) input utilization in Brazilian agricultural systems is low (50 %) but can be improved by adopting appropriate management strategies. Objective or research question: The objective of this study was to assess and quantify the combined long-term effects of soil tillage and rates and forms of P fertilizer inputs on soybean [Glycine max (L.) Merr.] and maize (Zea mays L.) yield, P use efficiency and soil P availability in a high P-fixing tropical soil. Methods: A comprehensive 22-year field experiment was undertaken in a Brazilian Cerrado soil with two soil tillage systems (conventional-CT and no-tillage-NT) combined with five P fertilizer management, being two sources of P [triple superphosphate (TSP) and Gafsa reactive phosphate rock (RPR)], under two annual rates of P (22 and 44 kg ha-1), and one control (no P application). Measurements included crop yield, removed P, partial P balance, and soil P [total P, legacy P, and labile P (Mehlich-3)]. Results: The NT and CT systems were equally productive. Plant yield responses were similar for TSP and RPR when 44 kg ha-1 of P was applied annually, although maize grain yield was 6 % higher for TSP compared with RPR at the lower rate of P application (22 kg ha-1 yr-1of P). The low P input rate was not enough to meet crop demand since the partial P balance was 131 % compared with 80 % for the high P input rate, both under TSP application. The same behavior was verified under RPR application, being 115 % compared with 74 % for the low and high rate of P, respectively. In the soil, CT system showed narrower differences between treatments, with a homogeneous distribution of P in depth compared with NT, while the NT system resulted in enhanced P accumulation in the topsoil, especially at the high rate of P fertilizer input. Conclusions: Our findings indicate that the use of an intermediate rate between 22 and 44 kg ha-1 yr-1 of P by RPR or TSP, especially under NT, is a recommended management strategy to optimize P utilization by maize and soybean while increase soil P bioavailability in a high P fixing tropical soil. Implications or significance: This study confirms that improving phosphate fertilization and soil management practices is key to ensuring the sustainable and efficient utilization of P in tropical agricultural systems.

Context Sustainable agricultural production relies on efficient phosphorus (P) management due to the finite nature of phosphate rock reserves, increasing fertiliser costs for farmers, and environmental concerns associated with P losses. Struvite, a P fertiliser recovered from wastewater, appears to be an alternative to conventional water soluble-P fertilisers. Aims We aimed to evaluate changes in the concentration of soil available P in response to the application of struvite in three New Zealand acidic soils with varied P retention capacities. Methods A plant-less incubation was carried out for 63 days where struvite, two water soluble-P fertilisers, and reactive phosphate rock were applied at two rates to three contrasting soils. Key results Regardless of soil type, struvite significantly increased Olsen-P concentrations, comparable to conventional P fertilisers. P retention capacity influenced P release patterns, with Pallic soil exhibiting the highest Olsen-P increases due to its low P retention. P release from struvite was rapid but showed sustained availability in Pallic soil compared to declines in Allophanic and Brown soils. Conclusions Struvite showed similar fertiliser-P behaviour in soils with contrasting P retention capacity generating changes in Olsen-P like those from water-soluble P fertilisers. Implications Further research is necessary to investigate the suitability of struvite as an alternative P fertiliser source for New Zealand agriculture.

Root-lesion nematodes (Pratylenchus spp.) are significant plant parasites, causing substantial crop damage worldwide. This study aimed to characterize Pratylenchus spp. in New Zealand maize fields using molecular techniques and map their prevalence. Soil sampling from 24 maize fields across the North and South Islands provided 381 composite samples. Root-lesion nematodes were extracted using the sieving-centrifugal-sugar flotation method and differentiated into five morphospecies. Molecular characterization involved direct partial sequencing of the D2/D3 28S rDNA, ITS rDNA, and COX1 mtDNA regions using Sanger technology from a single nematode. Five Pratylenchus species were identified: P. neglectus, P. crenatus, P. thornei, P. penetrans, and P. pratensis, confirmed by phylogenetic analysis. Prevalence mapping showed P. neglectus and P. crenatus in all sampled fields, while P. thornei, P. penetrans, and P. pratensis were more localized. This study is the first to report these Pratylenchus species on maize in New Zealand and provides the first partial sequences of the D2/D3, COX1, and ITS regions for these species on maize in New Zealand. The findings highlight the diversity of Pratylenchus populations in New Zealand maize fields and emphasize the need for region-specific management strategies to mitigate crop damage.

Phosphorus (P) inputs are essential for increasing and maintaining global agroecosystem productivity. However, concerns persist over the long-term availability and rising cost of the P needed to sustain future food production. Most soils have a high P retention (fixation) capacity, limiting P availability and use efficiency (often <50%), and leading to the accumulation of residual P in soil (i.e. legacy soil P). Over time, this legacy P contributes to water eutrophication through diffuse losses via runoff and leaching. Despite its environmental risks, legacy soil P represents a significant resource that could be partially mobilized to reduce the need for new P inputs while maintaining productivity. However, its availability to plants depends on soil properties, environmental conditions, crop species, and management practices. Management options designed to lower accumulation and increase mobilization of legacy soil P include avoiding excess P inputs, replacing conventional water-soluble fertilizers with sparingly soluble alternatives (e.g. reactive phosphate rock, struvite), integration of P-efficient plant species into crop rotations (e.g. green manures), and optimizing biological processes known to improve P use efficiency by plants (e.g. mycorrhizae inoculation). © The Authors 2025

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 change. Using SparCC-based co-occurrence networks, we studied how land use change impacts the connectivity, complexity, and stability of microbial C-cycling gene networks across an agricultural mosaic landscape in Canterbury, New Zealand. The most densely connected networks were found in land uses that were under the most intensive agricultural management, or under naturally regenerating vegetation. The microbial C-cycling gene networks from both land uses presented high network connectivity, low modularity, and a low proportion of negative gene interactions. In contrast, microbial C-cycling genes from native forests, which had the most stable and undisturbed plant cover, had the lowest network connectivity, highest modularity, and a greater proportion of negative gene interactions. Although the differences in total soil C content between land uses were small, the large effects of land use on the network structure of microbial C-cycling genes may have important implications for long-term microbial soil C cycling. Furthermore, this research highlights the value of using microbial network analysis to study the metabolic gene interactions shaping the functional structure of soil microbial communities in a manner not typically captured by more traditional forms of microbial diversity analysis.

Context or problem The efficiency of phosphorus (P) input utilization in Brazilian agricultural systems is low (50 %) but can be improved by adopting appropriate management strategies. Objective or research question The objective of this study was to assess and quantify the combined long-term effects of soil tillage and rates and forms of P fertilizer inputs on soybean [Glycine max (L.) Merr.] and maize (Zea mays L.) yield, P use efficiency and soil P availability in a high P-fixing tropical soil. Methods A comprehensive 22-year field experiment was undertaken in a Brazilian Cerrado soil with two soil tillage systems (conventional-CT and no-tillage-NT) combined with five P fertilizer management, being two sources of P [triple superphosphate (TSP) and Gafsa reactive phosphate rock (RPR)], under two annual rates of P (22 and 44 kg ha–1), and one control (no P application). Measurements included crop yield, removed P, partial P balance, and soil P [total P, legacy P, and labile P (Mehlich-3)]. Results The NT and CT systems were equally productive. Plant yield responses were similar for TSP and RPR when 44 kg ha–1 of P was applied annually, although maize grain yield was 6 % higher for TSP compared with RPR at the lower rate of P application (22 kg ha–1 yr–1of P). The low P input rate was not enough to meet crop demand since the partial P balance was 131 % compared with 80 % for the high P input rate, both under TSP application. The same behavior was verified under RPR application, being 115 % compared with 74 % for the low and high rate of P, respectively. In the soil, CT system showed narrower differences between treatments, with a homogeneous distribution of P in depth compared with NT, while the NT system resulted in enhanced P accumulation in the topsoil, especially at the high rate of P fertilizer input. Conclusions Our findings indicate that the use of an intermediate rate between 22 and 44 kg ha–1 yr–1 of P by RPR or TSP, especially under NT, is a recommended management strategy to optimize P utilization by maize and soybean while increase soil P bioavailability in a high P fixing tropical soil. Implications or significance This study confirms that improving phosphate fertilization and soil management practices is key to ensuring the sustainable and efficient utilization of P in tropical agricultural systems.

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 review highlights recent major research updates. Interest in organic P research has increased since 2016, and new priorities have emerged, including the impact of climate change on organic P, the influence of geopolitical crises on P supplies, and the adoption of sustainable practices like regenerative agriculture. Climate change was a central theme in the 2023 discussions, with an increased emphasis on integrating P and especially organic P into climate change research, which has traditionally focused more on carbon (C) and nitrogen (N). The discussions highlighted disparities in accessing analytical equipment globally, and its consequent impact on research quality and scope. To address these issues, coordinated efforts involving the research community, government policies, and international cooperation are needed, much the same as we see with the climate and biodiversity crises. Promoting sustainable agricultural practices, investing in soil health, and enhancing education and extension services are crucial. Future research should focus on standardizing analytical methods, integrating nutrient balance into models, and exploring soil-microbiome-plant interactions. Regular and intedisciplinary workshops, social media engagement, and the establishment of research networks are recommended to maintain momentum in organic P research. Raising public and stakeholder awareness about the importance of organic P is essential for advancing knowledge in this area.

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 angustifolius (lupin – early and late flowering varieties), Pisum sativum (pea), Cicer Arietinum (chickpea), and Fagopyrum escolentum (buckwheat)) were grown in two contrasting soils, pumice (1100 mg total P kg−1, anion storage capacity 39%) and volcanic ash (2800 mg total P kg−1, anion storage capacity 95%) in rhizosphere study containers. After 40 days, rhizosphere (0–5 mm) and bulk (>5 mm) soils were sampled and subjected to P fractionation. Organic anions were collected from the rhizoplane using an anion exchange membrane. Key results Dry matter yield, P uptake, and rhizoplane organic anion exudation were affected by plant species, soil type, and their interaction. Rhizosphere P changes of labile inorganic organic P and stable inorganic P were influenced by plant species and soil type, while moderately labile inorganic P was affected by only plant species. Interaction between plant species and soil type had no effect on rhizosphere P depletion or accumulation. The quantities and composition of organic anions determined in rhizoplane exudates were highly variable (0.01–0.1 μmol cm−2 h−1). However, significant correlations were observed between the depletion of moderately labile and stable soil inorganic P and concentrations of malate in exudates. Conclusions The findings of this study clearly demonstrated the capacity of green manure crops (especially blue lupin) to rapidly mobilise and deplete different forms of soil P across the soil types.

This study examines differences in extraction efficiency of three methods for extracting root-lesion nematodes (Pratylenchus spp.) from maize roots. The Baermann funnel, Whitehead & Hemming tray, and centrifugal-sugar flotation methods were evaluated for efficiency and clarity using microscopic observation. Statistical analysis confirmed significant differences among the methods. The centrifugal-sugar flotation method yielded the highest nematode count (1874±76 per 5 g of roots) but the clarity of the observation field under the microscope was lower due to root residues compared to the other two tested methods. The Baermann funnel method yielded 35.9% extraction efficiency (672±46 per 5 g of roots) compared to the centrifugal-sugar flotation method with higher clarity of the observation field than other tested methods. The Whitehead & Hemming tray presented a moderate level of observation field clarity compared to other tested methods with a nematode extraction efficiency of 60.8% (1140±53 per 5 g of roots) compared to the centrifugal-sugar flotation method. The results suggest that the Whitehead & Hemming tray could be a viable choice for nematode extraction, especially when both nematode numbers and microscopic clarity are important considerations. Understanding the restrictions of each methodology enhances the accuracy of nematode quantification leading to improved and updated data for maize producers in New Zealand.

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 fertilizers. When P inputs are not fully removed with harvest of crop biomass, the remaining P accumulates in soils. This residual P is a uniquely anthropogenic pool of P, and its management is critical for agronomic and environmental sustainability. Managing residual P first requires its quantification-but measuring residual P is challenging. In this review, we synthesize approaches to quantifying residual P, with emphasis on advantages, disadvantages, and complementarity. Common approaches to estimate residual P are mass balances, long-term experiments, soil test P trends and chronosequences, with varying suitability or even limitations to distinct spatiotemporal scales. We demonstrate that individual quantification approaches are (i) constrained, (ii) often complementary, and (iii) may be feasible at only certain time-space scales. While some of these challenges are inherent to the quantification approach, in many cases there are surmountable challenges that can be addressed by unifying existing P pool and flux datasets, standardizing and synchronizing data collection on pools and fluxes, and quantifying uncertainty. Though defined as a magnitude, the distribution and speciation of residual P is relatively less understood but shapes its utilization and environmental impacts. The form of residual P will vary by agroecosystem context due to edaphoclimatic-specific transformation of the accumulated P, which has implications for management (e.g., crop usage) and future policies (e.g., lag times in P loading from non-point sources). Quantifying the uncertainty in measuring residual P holds value beyond scientific understanding, as it supports prioritization of monitoring and management resources and inform policy.

Plant-parasitic nematodes (PPNs) are significant agricultural pests that can reduce maize yields. This study examines the prevalence, abundance, and diversity of PPNs in New Zealand maize fields, focusing on the effects of territory, soil orders, crop stages, and sampling times. Seven PPN genera were identified: Pratylenchus spp. (root-lesion), Helicotylenchus spp. (spiral), Meloidogyne spp. (root-knot), Heterodera spp. (cyst), Paratylenchus spp. (pin), Criconemella spp. (ring), and Tylenchus spp. PPNs were present in 98% of the samples, with Pratylenchus spp. being the most prevalent (91%), followed by Helicotylenchus spp. (38%). Compared to Waikato and Manawatu-Whanganui, Canterbury had the highest nematode populations, particularly of Pratylenchus spp. and Helicotylenchus spp. Brown and pallic soils supported higher PPN abundances. Sampling during the maize harvesting stage and late autumn resulted in the highest nematode populations and diversity indices. Pratylenchus spp. populations often exceeded the economic threshold of 500 Pratylenchus kg-1 of soil, suggesting a significant threat to maize yield in New Zealand. The findings highlight the need for further research to assess the impact of Pratylenchus spp. on maize yield and to develop effective management practices for maize cultivation in the country.

The efficiency of soil phosphorus (P) mobilization and uptake by plants depends on a complex combination of factors, including plant P acquisition strategies and soil P availability. The objective of this study was to assess and compare the capabilities of three legume species (blue lupin (Lupinus angustifolius L.), faba bean (Vicia faba L.), and chickpea (Cicer arietinum L.)), which may be used as green manures in temperate crop systems to acquire P from a soil with different levels of plant-available P. Three cycles of each legume were grown in a glasshouse over a 6 month period in the same soil type with high (Olsen P: 47 mg kg(-1)) and low (Olsen P: 9 mg kg(-1)) levels of plant-available P. Measurements included above-and below-ground plant biomass and P uptake, in addition to determination of acid and alkaline phosphomonoesterase activities, microbial P, and P fractions in soil at the end of the experiment. In both soils, plant biomass, P uptake, and microbial P were all higher under faba bean compared to blue lupin and chickpea (p < .05). In the low-P soil, faba bean increased alkaline phosphomonoesterase activity (p < .05). Significant depletion of inorganic P in the soluble (46%-69%), labile (29%-42%), and moderately labile (15%-16%) pools and increase of organic P in the labile (13%-18%) and total (7%-13%) pools occurred under faba bean compared with blue lupin, while changes under chickpea were between those determined for faba bean and blue lupin (p < .05). The findings of this study indicated that inclusion of faba bean green manure may have the potential to improve overall P use efficiency by enhancing mobilization of labile soil inorganic P, although further research is required to investigate mobilization of more stable forms of soil legacy P and quantify the potential of faba bean as a green manure crop under field conditions.

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 pathogenic, root-associated fungi (hereafter, 'pathogens') in communities invaded by exotic plants, we conducted a two-phase plant-soil feedback experiment: a monoculture experiment with native and exotic plants grown alone and a multi-species, community-level experiment that ranged in the extent of exotic dominance. We used next-generation sequencing to characterise sharing of pathogens between native and exotic plants in communities. Exotic plants outperformed natives in communities, despite harbouring higher relative abundance of generalist pathogens. The higher generalism of pathogens supported by exotic plants made them more prone to be shared with natives. The proportion of pathogens shared between exotic and native plants in communities correlated with reduced competitive ability of native compared with exotic plants. Synthesis: These data suggest that exotic plants host more generalist pathogens that are shared with native plants, which may confer an indirect benefit to exotic over native plants through apparent competition. Exotic plants outperformed natives in communities, despite harbouring higher relative abundance of generalist pathogens. The relative abundance of generalist fungal pathogens increased, and arbuscular mycorrhizal fungi decreased with increasing exotic dominance. This analysis suggests that exotic plants host more generalist pathogens that are shared with native plants, which may confer an indirect benefit to exotic plants through apparent competition.image

ABSTRACTIntroductionIn 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 interactions under green manures can mobilise soil legacy P and promote cereal crop P uptake and growth.MethodsAlongside a fallow treatment, three green manure treatments that included two legume treatments (narrow‐leaf lupin [Lupinus angustifolius], pea [Pisum sativum L.]) and one cereal treatment (wheat [Triticum aestivum] and barley [Hordeum vulgare]) were rotated with the main crops of wheat and barley in two phases on a pumice soil (27 mg kg−1 Olsen P) in a microcosm experiment. Plant roots and shoots and end‐of‐experiment soil samples were collected for analysis.ResultsOver two crop rotations, inclusion of narrow‐leaf lupin and pea green manures significantly increased main crop biomass (27%–35%) and P uptake (15%–29%) relative to control, while the cereal green manure decreased the following crop's yield (−13%) and P uptake (−19%). Relative to fallow, microbial biomass P and soil organic P pools increased under all green manures yet total inorganic P decreased under leguminous green manures. This depletion (35 mg P kg−1) under narrow‐leaf lupin was equivalent to ~47 kg P ha−1. Phosphatase enzyme activities relevant to P cycling increased particularly under leguminous green manure treatments.ConclusionsLeguminous green manures such as narrow‐leaf lupin could mobilise soil P to crops in field conditions, suggesting that drawdown of soil legacy P while sustaining crop yield can be tenable.

Soil carbon (C) storage is a critical ecosystem function that underpins human health and well-being. The acceleration of human-driven land use change, such as agricultural intensification, is a major driver of soil C loss globally. Developing sustainable land use practices that enhance agricultural productivity whilst protecting essential ecosystem functions such as soil C storage is vital. The soil microbiome has a critical role in regulating soil biogeochemical cycling processes, including soil C cycling. Examining the impacts of land use intensity on the soil microbiome enables us to assess the potential effects on long-term soil C stocks. Using metagenomic DNA sequencing and phospholipid fatty acid analysis, we investigated differences in the activity, diversity, and function of the soil microbiome associated with five contrasting land uses across an agricultural landscape. The land uses covered a gradient of disturbance intensities and included remnant native forest, regenerating native bush, exotic plantation forest, dryland pasture, and irrigated pasture. We identified pronounced differences in the soil microbiome associated with each land use, including the diversity and abundance of microbial C and nitrogen (N) cycling genes. Notably, intensive agricultural land uses had a significantly higher diversity and abundance of microbial C-degrading genes, whilst land uses of remnant native forest had the lowest diversity and abundance of microbial C-degrading genes. Our findings suggest that intensive agricultural land use may increase the functional potential of the soil microbiome to mineralize soil C, potentially resulting in a greater loss of soil C as respired CO2 into the atmosphere. This research may be used to support the development of sustainable management practices that promote the persistence of soil C across agricultural landscapes, such as the protection of remnant native forest fragments and greater incorporation of regenerating native vegetation.

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 to explore the impacts of forest disturbance and disease outbreaks on the biosynthetic potential and taxonomic diversity of the kauri soil microbiome. We explored the diversity of secondary metabolite biosynthetic gene clusters (BGCs) in soils from a range of kauri forests that varied according to historical disturbance and dieback expression. To characterise the diversity of microbial BGCs, we targeted the non-ribosomal peptide synthetase (NRPS) and polyketide synthetase (PKS) gene regions for sequencing using long-read PacBio® HiFi sequencing. Furthermore, the soil bacterial and fungal communities of each forest were characterized using 16 S rRNA and ITS gene region sequencing. We identified a diverse array of naturally occurring microbial BGCs in the kauri forest soils, which may offer promising targets for the exploration of secondary metabolites with anti-microbial activity against P. agathidicida. We detected differences in the number and diversity of microbial BGCs according to forest disturbance history. Notably, soils associated with the most undisturbed kauri forest had a higher number and diversity of microbial NRPS-type BGCs, which may serve as a potential indicator of natural levels of microbiome resistance to pathogen invasion. By linking patterns in microbial biosynthetic diversity to forest disturbance history, this research highlights the need for us to consider the influence of ecological disturbances in potentially predisposing forests to disease by impacting the wider health of forest soil ecosystems. Furthermore, by identifying the range of microbial BGCs present at a naturally high abundance in kauri soils, this research contributes to the future discovery of natural microbial compounds that may potentially enhance the disease resilience of kauri forests. The methodological approaches used in this study highlight the value of moving beyond a taxonomic lens when examining the response of microbial communities to ecosystem disturbance and the need to develop more functional measures of microbial community resilience to invasive plant pathogens.

Phosphorus (P) is a key element for energy transfer, and biosynthesis of nucleic acids and cell membranes. The objective of this study was to investigate and quantify P utilization by different grain—maize (Zea mays L.) and soybean (Glycine max L.)—and forage-cover crop brachiaria (Brachiaria ruziziensis) plant species in a low fertility highly weathered Oxisol. Two rates of P (25 and 50 mg kg−1) were applied by water-soluble P fertilizer (triple superphosphate) to each of 12 crop cycles, together with a control (no P added). Measurements included plant biomass production and P uptake for each cycle, and analysis of soil P fractions (including labile and non-labile) and enzymes activities (acid phosphatase and β-glucosidase) were done at the beginning of the experiment and after 3, 6, and 12 cycles. Total biomass production and P uptake/removal were significantly higher for brachiaria than maize and soybean, which was reflected in the P use efficiency (PUE), being higher for brachiaria (57