17 research outputs found
Inter- and intra-species intercropping of barley cultivars and legume species, as affected by soil phosphorus availability
Aims: Intercropping can improve plant yields and
soil phosphorus (P) use efficiency. This study
compares inter- and intra-species intercropping,
and determines whether P uptake and shoot biomass
accumulation in intercrops are affected by
soil P availability.
Methods: Four barley cultivars (Hordeum vulgare L.)
and three legume species (Trifolium subterreneum,
Ornithopus sativus and Medicago truncatula) were selected
on the basis of their contrasting root exudation
and morphological responses to P deficiency. Monocultures
and barley-barley and barley-legume intercrops
were grown for 6 weeks in a pot trial at very limiting,
slightly limiting and excess available soil P. Aboveground
biomass and shoot P were measured.
Results: Barley-legume intercrops had 10â70%
greater P accumulation and 0â40% greater biomass
than monocultures, with the greatest gains occurring
at or below the sub-critical P requirement for
barley. No benefit of barley-barley intercropping
was observed. The plant combination had no significant
effect on biomass and P uptake observed
in intercropped treatments.
Conclusions: Barley-legume intercropping shows
promise for sustainable production systems, especially
at low soil P. Gains in biomass and P uptake
come from inter- rather than intra-species
intercropping, indicating that plant diversity resulted
in decreased competition between plants for P
On pedagogy of a Soil Science Centre for Doctoral Training
Here we describe and evaluate the success of a multi-institutional Centre for Doctoral Training (CDT), which was established to address a UK skills shortage in Soil Science. The government-funded âSTARSâ (Soils Training And Research Studentships) CDT was established in 2015 across a range of universities and research institutes in the UK. It recruited 41 PhD students equitably split across the institutions under four core research themes identified as being central to the national need, namely, (1) Understanding the soilâroot interface, (2) Soils and the delivery of ecosystem services, (3) Resilience and response of functions in soil systems and (4) Modelling the soil ecosystem at different spatial and temporal scales. In addition, the STARS CDT provided a diverse skills programme, including: Holistic training in soils, the promotion of collegiality and joint working, strategies to promote science and generate impact, internships with end users (e.g., policymakers, industry), personal wellbeing, and ways to generate a lasting soils training legacy. Overall, both supervisors and students have reported a positive experience of the CDT in comparison to the conventional doctoral training programmes, which have less discipline focus and little chance for students to scientifically interact with their cohorts or to undertake joint training activities. The STARS CDT also allowed students to freely access research infrastructure across the partner institutions (e.g., long-term field trials, specialised analytical facilities, high-performance computing), breaking down traditional institutional barriers and thus maximising the students' potential to undertake high-quality research. The success and legacy of the STARS CDT can be evidenced in many ways; however, it is exemplified by the large number and diversity of journal papers produced, the lasting collaborations, final career destinations, and creation of a web-based legacy portal including new and reflective video material.STARS CDT, Grant/Award Numbers: NE/V017667/1, NE/R010218/1, NE/M009106/1; UKR
Response-based selection of barley cultivars and legume species for complementarity:root morphology and exudation in relation to nutrient source
Phosphorus (P) and nitrogen (N) use efficiency may be improved through increased biodiversity in agroecosystems. Phenotypic variation in plantsâ response to nutrient deficiency may influence positive complementarity in intercropping systems. A multicomponent screening approach was used to assess the influence of P supply and N source on the phenotypic plasticity of nutrient foraging traits in barley (H. vulgare L.) and legume species. Root morphology and exudation were determined in six plant nutrient treatments. A clear divergence in the response of barley and legumes to the nutrient treatments was observed. Root morphology varied most among legumes, whereas exudate citrate and phytase activity were most variable in barley. Changes in root morphology were minimized in plants provided with ammonium in comparison to nitrate but increased under P deficiency. Exudate phytase activity and pH varied with legume species, whereas citrate efflux, specific root length, and root diameter lengths were more variable among barley cultivars. Three legume species and four barley cultivars were identified as the most responsive to P deficiency and the most contrasting of the cultivars and species tested. Phenotypic response to nutrient availability may be a promising approach for the selection of plant combinations for minimal input cropping systems
Linking the depletion of rhizosphere phosphorus to the heterologous expression of a fungal phytase in Nicotiana tabacum as revealed by enzyme-labile P and solution 31P NMR spectroscopy
Root exudation of phytase could improve the ability of plants to access organic forms of soil phosphorus (P), thereby minimizing fertilizer requirements and improving P use efficiency in agroecosystems. After 75 days growth in a high available P soil, shoot biomass and P accumulation, soil pH, and rhizosphere P depletion were investigated in Nicotiana tabacum wild-type and transgenic plant-lines expressing and exuding Aspergillus niger phytase (ex::phyA), or a null-vector control. Solution 31P NMR analysis revealed a 7% to 11% increase in orthophosphate and a comparable depletion of undefined monoester P compounds (-13 to -18%) in the rhizosphere of tobacco plants relative to the unplanted soil control. Wild-type plants had the greatest impact on the composition of rhizosphere P based on the depletion of other monoester P, polyphosphate, and phosphonate species. The depletion of phytase-labile P by ex::phyA plants was associated with decreased proportions of other monoester P, rather than myo-InsP6 as expected. Rhizosphere pH increased from 6.0 to 6.5â6.7 in transgenic plant soils, beyond the pH optimum for A. niger phyA activity (pH=5), and may explain the limited specificity of ex::phyA plants for phytate in this soil. The efficacy of single exudation traits (e.g., phytase) therefore appear to be limited in P-replete soil conditions and may be improved where soil pH matches the functional requirements of the enzyme or trait of interest
Opportunity to improve global phosphorus governance : Nutrient Cycling
Nutrient recycling is key for the circularity and sustainability of food systems. Understanding the movement of phosphorus through trade enables better geospatial planning and highlights opportunities for more effective global phosphorus governance
Corrigendum to âUsing a meta-analysis approach to understand complexity in soil biodiversity and phosphorus acquisition in plantsâ [Soil Biol. Biochem. 142 (2020) 107695]
Current soil phosphorus (P) management is neither environmentally nor economically sustainable. Soil biodi-versity has been offered as a solution to unsustainable land management and to promote ecosystem service provision. We know soil biology is instrumental in plant access to soil P, but specific effects of biological complexity, (used here to describe the number of links between different organisms), under different P levels on plant productivity are not well understood. We conducted a meta-analysis on relevant literature, which reported the response of terrestrial plants of economic and anthropogenic importance to P conditions, and controlled for biological treatments across different land-uses (arable, grassland and woodland). We hypothesised that: 1) in arable systems increased biological complexity will enhance plant productivity; 2) in perennial systems such as grassland and woodlands, increasing biological complexity will have no effect; 3) increasing the fertility of the system by addition of P fertiliser will reduce any benefits of biological complexity. We found that soil organisms are not always beneficial to plant shoot biomass, but that the effects of - and interaction among - bacteria, protozoa, nematodes, mycorrhizae, collembola and earthworms differ in their impact on plant biomass (positive or negative) dependent on the presence of other community members, P-level status and time. These findings bring into question existing frameworks that link below-ground biodiversity with above-ground plant produc-tivity. We recommend further experimental work be conducted, which controls for land-use, P status, and soil biological composition and complexity. Such work should be followed by future systematic reviews, which could pragmatically inform more tailored biological management for plant P requirements, land-use and ecosystem service provision. To enable further meta-analyses of this type we recommend habitual inclusion of sufficient experimental detail and data, as a prerequisite for publication and a useful way to utilise increased online publication spac
Using a meta-analysis approach to understand complexity in soil biodiversity and phosphorous acquisition in plants
Current soil phosphorous (P) management is neither environmentally nor economically sustainable. Soil biodiversity has been offered as a solution to unsustainable land management and to promote ecosystem service provision. We know soil biology is instrumental in plant access to soil P, but specific effects of biological complexity, (used here to describe the number of links between different organisms), under different P levels on plant productivity are not well understood. We conducted a meta-analysis on relevant literature, which reported the response of terrestrial plants of economic and anthropogenic importance to P conditions, and controlled for biological treatments across different land-uses (arable, grassland and woodland). We hypothesised that: 1) in arable systems increased biological complexity will enhance plant productivity; 2) in perennial systems such as grassland and woodlands, increasing biological complexity will have no effect; 3) increasing the fertility of the system by addition of P fertiliser will reduce any benefits of biological complexity. We found that soil organisms are not always beneficial to plant shoot biomass, but that the effects of - and interaction among - bacteria, protozoa, nematodes, mycorrhizae, collembola and earthworms differ in their impact on plant biomass (positive or negative) dependent on the presence of other community members, P-level status and time. These findings bring into question existing frameworks that link below-ground biodiversity with above-ground plant productivity. We recommend further experimental work be conducted, which controls for land-use, P status, and soil biological composition and complexity. Such work should be followed by future systematic reviews, which could pragmatically inform more tailored biological management for plant P requirements, land-use and ecosystem service provision. To enable further meta-analyses of this type we recommend habitual inclusion of sufficient experimental detail and data, as a prerequisite for publication and a useful way to utilise increased online publication space
Corrigendum to âUsing a meta-analysis approach to understand complexity in soil biodiversity and phosphorus acquisition in plantsâ [Soil Biol. Biochem. 142 (2020) 107695] (Soil Biology and Biochemistry (2020) 142, (S0038071719303591), (10.1016/j.soilbio.2019.107695))
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Effect of citrate on Aspergillus niger phytase adsorption and catalytic activity in soil
Phytase enzymes from bacteria, fungus and plant root exudates are known to hydrolyse organic phosphorus (Po) to bioavailable inorganic orthophosphate in soil. Exploiting such biochemical functions in agricultural systems, offers the potential for alternative sustainable phosphorus sources. Phytase adsorption to soil particles and phytate metal complexation has been shown to inhibit phytate (InsP6) dephosphorylation. Organic acid anions such as citrate increase phytase catalytic efficiency towards complexed forms of InsP6, but the mechanisms are poorly understood. The aim of this work was to evaluate Aspergillus niger phytase inactivation and changes in its catalytic properties upon addition to soil, as well as the effect of citrate on phytase adsorption and activity towards free, precipitated and adsorbed InsP6. We performed a series of enzyme hydrolysis activity assays when the enzymes were free, in soil solution and adsorbed to soil under varying chemical conditions, with and without citrate. A. niger phytase showed a relatively low absorption affinity for the Cambisol test soil. Phytase activity reduced by 37.3% due to adsorption. Citrate had no effect on the rate or total amount of phytase adsorption or soil adsorbed phytase activity thereafter. Free phytases and phytases in soil solution showed optimum activity (â„ 80%) at pH 4.5â5.5. Activity decreased slightly for soil adsorbed enzymes compared to enzymes which were free or in soil solution > pH 5 and 0.6 M in adsorbed and free enzymes, while activity from enzymes in soil solution reduced in all tested ionic strengths. Citrate significantly increased phytase activity towards InsP6 adsorbed to soil when the phytases were free (p †0.003) but not in other treatments (Na, Al and Ca-phytate). These results suggest that the effect of citrate on soil InsP6 dephosphorylation is associated with the availability of the substrate (InsP6) rather than its effect on the enzyme per se. The ionic strength and pH of soil solution has been shown to impact on phytase activity, suggesting that salinity, quality of irrigation water, wetting/drying cycles and fertilisation will have discrete impacts on the activity of phytases once released in soil and thus the ability to make Po available for uptake by plants and microbes. The optimum acidic pH of A. niger also brings into question its suitability for application in many agricultural soils
On pedagogy of a Soil Science Centre for Doctoral Training
Here we describe and evaluate the success of a multi-institutional Centre for Doctoral Training (CDT), which was established to address a UK skills shortage in Soil Science. The government-funded âSTARSâ (Soils Training And Research Studentships) CDT was established in 2015 across a range of universities and research institutes in the UK. It recruited 41 PhD students equitably split across the institutions under four core research themes identified as being central to the national need, namely, (1) Understanding the soilâroot interface, (2) Soils and the delivery of ecosystem services, (3) Resilience and response of functions in soil systems and (4) Modelling the soil ecosystem at different spatial and temporal scales. In addition, the STARS CDT provided a diverse skills programme, including: Holistic training in soils, the promotion of collegiality and joint working, strategies to promote science and generate impact, internships with end users (e.g., policymakers, industry), personal wellbeing, and ways to generate a lasting soils training legacy. Overall, both supervisors and students have reported a positive experience of the CDT in comparison to the conventional doctoral training programmes, which have less discipline focus and little chance for students to scientifically interact with their cohorts or to undertake joint training activities. The STARS CDT also allowed students to freely access research infrastructure across the partner institutions (e.g., long-term field trials, specialised analytical facilities, high-performance computing), breaking down traditional institutional barriers and thus maximising the students' potential to undertake high-quality research. The success and legacy of the STARS CDT can be evidenced in many ways; however, it is exemplified by the large number and diversity of journal papers produced, the lasting collaborations, final career destinations, and creation of a web-based legacy portal including new and reflective video material. Highlights: Soil science was identified as having a scientific skills shortage in the UK. A dedicated soil science Centre for Doctoral Training (CDT) was established to address this skills gap. The multi-institutional, discipline-focused CDT proved more successful than conventional generic PhD training programmes. The CDT model provides critical mass to provide more effective training of soil scientists