CERES :: Browsing by Author "Deeks, Lynda K."

Browsing by Author "Deeks, Lynda K."

Now showing 1 - 20 of 22

Open Access
Alternative cropping practices for sustainable soil management and yield optimisation in asparagus.
(Cranfield University, 2021-07) Maskova, Lucie; Simmons, Robert W.; Deeks, Lynda K.; De Baets, Sarah
Asparagus (Asparagus officinalis L.) is a high value perennial crop with long economic production period ranging between 10-20 years. Field operations associated with conventional UK asparagus production such as re-ridging and intensive foot and vehicular trafficking of the wheelings however run a danger of causing a range of negative environmental impacts and pose a risk to long-term asparagus productivity. Nonetheless, majority of British growers continues to cultivate asparagus in the conventional way due to a lack of alternatives to the conventional practice. The aim of this research is to critically evaluate the long-term efficacy of a set of potential best management practices (BMPs) targeted at preventing or remediating soil compaction in asparagus interrows, promoting root growth and increasing profitability of asparagus production. The research further aimed to quantify the impacts of annual re-ridging associated with the conventional production on soil compaction, root development, yields and on soil bio-chemical characteristics. The experimental field trial located in Herefordshire tested a range of potential BMPs inducing (i) companion cropping with either rye (Secale cereale L.) or mustard (Sinapis alba L.) which were re-ridged or non-ridged, (ii) interrow surface mulching with either straw mulch or compost which were re- ridged or non-ridged and (iii) a combination of tillage practices (ridging and shallow soil disturbance) applied to bare soil interrows. Treatments were applied annually from 2018-2020. This research showed that the field management practice currently adopted by the of British asparagus industry is unsustainable and poses high risks to both the soil environment and asparagus productivity. Key findings show that soil compaction, root growth, asparagus profitability and soil bio-chemistry in asparagus cropping systems can be effectively modified and managed by BMPs. Consequently, this research identified a set of BMPs to be considered for practical application.
Open Access
Application of artificial neural networks in the design of drainage systems in data-poor areas.
(Cranfield University, 2022-06) Ellafi, Murad; Simmons, Robert W.; Deeks, Lynda K.
Drainage has been identified as an often-neglected component of irrigated agriculture in arid and semi-arid areas. Even though it is accepted that drainage is often necessary to prevent waterlogging and salinity impacting productivity in irrigated agriculture, it is typically ignored when planning future irrigation schemes. Only 5 – 10% of the total irrigated land in Least Developed Countries (LDCs) that requires drainage is currently drained (compared to 25 – 30% in developed countries). This is partly due to a fundamental lack of spatially and temporally coherent datasets containing key input parameters for drainage models, local expertise and the high cost of drainage installation. Drainage simulation models can provide reliable predictions of multi-component systems to evaluate drainage system design over long periods (1 – 100 years). This study evaluated existing drainage simulation models (i.e. DRAINMOD, SWAP, ADAPT, RZWQM2, EPIC, WaSim and HYDRUS-1D) for their suitability to be applied in data-poor arid and semi-arid regions. Based on a selection criteria, the most applicable model for drainage design in arid and semi-arid areas was DRAINMOD. DRAINMOD, an agricultural drainage simulation model, is a versatile and readily available model that can be used to evaluate alternative drainage system designs. DRAINMOD requires several key inputs, including saturated hydraulic conductivity (Ksat), reference evapotranspiration (ET0) and the Electrical Conductivity of a saturated soil Extract (ECe). In LDCs, measuring these parameters is expensive and time-consuming. In addition, existing historic datasets are often spatially and temporally limited. Therefore, indirect approaches are needed to overcome incomplete data records that restrict drainage designs. This thesis evaluates the feasibility of applying indirect methods, with a focus on developing and validating the use of artificial neural networks (ANNs) using available historic measured datasets. The study data draws on the drainage design for Hammam Agricultural Project (HAP) and Eshkeda Agricultural Project (EAP), located in the south of Libya, north of the Sahara Desert. Soil texture, bulk density, field capacity, and wilting point were used to develop ANNs to predict Ksat which were significantly more accurate compared to widely adopted Pedotransfer functions (PTFs) such as Rosetta3. To calculate the daily ET0, average monthly maximum and minimum air temperature were used to develop ANNs. Arithmetic Averaging of Neighbouring Stations (AANS), MODAWEC and Era5-Land were among the indirect methods applied to predict ET0. Landsat 5 Surface Reflectance bands and the derived salinity indices were applied to develop ANNs to estimate ECe. The accuracy of the predicted values of Ksat, ET0 and ECe were evaluated by using statistical parameters such as coefficient of determination (R²), mean square error (MSE), and root mean square error (RMSE). The predicted Ksat and ET0 values were input to DRAINMOD to design drainage systems in EAP and HAP as compared to the optimum design based on measured data. The design focused on how accurately the predicted values were able to estimate drain spacing, relative yield, irrigation depth, and drainage discharge. The key findings showed that the accuracy of predicting Ksat greatly impacted predicting the optimum drain spacing and the associated relative yield. Accurate prediction of the optimum spacing between drains will reduce the overall cost by ensuring that the drains are not spaced too closely, but also lowers the risk of raising the water table and negatively impacting the yield by preventing the drains being installed on too wider a spacing. In addition, precisely predicting ET0 is essential to quantify the irrigation water requirement and drainage discharge. Finally, predicting soil salinity using remote sensing data can be used as an early warning tool to monitor irrigated lands affected by salinity, evaluate the performance of existing drainage systems, and indicate areas that need improvement. Future research recommendations identified by this research include the need for (1) critical evaluation of the accuracy of using ANNs and other machine learning approaches to predict other input parameters required for drainage design such as the water retention curve, depth of impermeable layer, hourly or daily rainfall, and initial water table depth. (2) development and validation of ANNs and other machine learning approaches that can predict Ksat, ET0, and ECe on a national level (Libya) and/or regional level (Middle East and North Africa) to overcome the challenge of incomplete data records that restrict drainage designs.
Open Access
Application of artificial neural networks to the design of subsurface drainage systems in Libyan agricultural projects
(Elsevier, 2021-05-18) Ellafi, Murad A.; Deeks, Lynda K.; Simmons, Robert W.
Study region The study data draws on the drainage design for Hammam agricultural project (HAP) and Eshkeda agricultural project (EAP), located in the south of Libya, north of the Sahara Desert. The results of this study are applicable to other arid areas. Study focus This study aims to improve the prediction of saturated hydraulic conductivity (Ksat) to enhance the efficacy of drainage system design in data-poor areas. Artificial Neural Networks (ANNs) were developed to estimate Ksat and compared with empirical regression-type Pedotransfer Function (PTF) equations. Subsequently, the ANNs and PTFs estimated Ksat values were used in EnDrain software to design subsurface drainage systems which were evaluated against designs using measured Ksat values. New hydrological insights Results showed that ANNs more accurately predicted Ksat than PTFs. Drainage design based on PTFs predictions (1) result in a deeper water-level and (2) higher drainage density, increasing costs. Drainage designs based on ANNs predictions gave drain spacing and water table depth equivalent to those predicted using measured data. The results of this study indicate that ANNs can be developed using existing and under-utilised data sets and applied successfully to data-poor areas. As Ksat is time-consuming to measure, basing drainage designs on ANN predictions generated from alternative datasets will reduce the overall cost of drainage designs making them more accessible to farmers, planners, and decision-makers in least developed countries.
Open Access
Best management practices to alleviate deep-seated compaction in asparagus (Asparagus officinalis) interrows (UK)
(Elsevier, 2021-07-03) Mašková, Lucie; Simmons, Robert W.; Deeks, Lynda K.; De Baets, Sarah
Field operations associated with UK asparagus production (re-ridging and intensive foot and vehicular trafficking of the wheelings) can result in severe deep-seated compaction in interrows, impacting on crop health and productivity. In this project, we investigate the long-term efficacy of a range of Best Management Practices (BMPs) targeted at preventing or remediating soil compaction in asparagus (Asparagus officinalis L.) interrows as compared to Conventional practice. BMPs included (1) companion crops - Rye (Sereale cecale L.), Mustard (Sinapis alba L.), (2) interrow surface mulch applications (straw mulch and PAS 100 compost in combination with shallow soil disturbance (SSD)), (3) modifications of the conventional tillage practice (re-ridging (R) or not ridging (NR) and applying SSD or not applying SSD) and (4) a zero-tillage option. In general, companion cropping had no effect on soil compaction or water infiltration rates as compared to the Conventional practice. Application and incorporation of straw mulch or PAS 100 compost however significantly reduced soil compaction of the interrows to >0.45 m beyond the working depth of the subsoiler (0.25 m). Composts and mulches in combination with SSD significantly reduce deep-seated compaction of the interrows within 3 years of annual application. Further, Conventional practice equivalent treatment (Bare soil No-SSD R) was associated with significantly higher PR values as compared to the zero-tillage (Bare soil No-SSD NR). These findings show that the extremely high levels of deep-seated compaction in interrows, associated with re-ridging, foot and vehicular traffic can be alleviated using surface mulches in combination with SSD.
Open Access
The contribution of natural burials to soil ecosystem services: review and emergent research questions
(Elsevier, 2023-11-22) Pawlett, Mark; Girkin, Nicholas T.; Deeks, Lynda K.; Evans, Daniel L.; Sakrabani, Ruben; Masters, Peter; Garnett, Kenisha; Marquez-Grant, Nicholas
The modern funeral industry faces many environmental risks and challenges, such as the use of sustainable materials for coffins, the release of potentially damaging materials and organisms to the soil and groundwater, and reduced space available for cemeteries. “Natural burial” proposes an alternative and more sustainable funeral practice, omitting the use of preservatives that inhibit body decomposition, thus proposing to reduce environmental degradation and benefit soil ecosystem services. This study conducted a literature review to identify proposed risks and benefits of “natural” compared to “traditional” burial practices, identifies knowledge gaps, and proposes further research questions. The approach was multidisciplinary, including literature from soil, environmental, forensic, and archaeological sciences, and the Humanities. Results identified that here are some clear environmental benefits to natural burial, such as habitat creation and aboveground biodiversity. However, there is a substantial deficit of research that compares the unseen risks and benefits of natural burial practice. Multiple potential risk factors include: (i) groundwater contaminated with biochemical products of decomposition, pathogens, and pharmaceutical products, (ii) atmospheric emissions, including greenhouse gases (CO2, CH4, N2O). There is also a deficit of information related to the release of cadaver decomposition products to soil ecological processes. More detailed scientific research is required to identify the risks and benefits of funeral options, thus develop fit for purpose regulations and legislation and to describe the cultural incentives for natural burial. This paper identifies key areas of research required to understand and mitigate the potential environmental and cultural implications of human burial practices.
Open Access
Cover crops for sustainable maize production.
(2017-12) Mancini, Agnese; Pawlett, Mark; Deeks, Lynda K.
Conventional maize-after-maize in the UK is frequently associated with soil compaction, runoff and soil erosion, due to a late autumn harvest and a post-harvest management that leaves minimal soil protection. Consequently, maize cultivation leads to on-site soil degradation and off-site environmental pollution. Soil conservation practices such as cover cropping could improve the sustainability of maize. Two field experiments were established within commercially grown maize (Herefordshire) in two consecutive years to investigate the role of different species of cover crops in reducing runoff, preventing soil erosion and enhancing soil microbial community. Experiment 1 compared common non-cover crop post-harvest managements with Lolium multiflorum and Secale cereale. Experiment 2 compared Lolium multiflorum and the mixtures Lolium multiflorum & Vicia villosa and Lolium multiflorum & Trifolium alexandrinum with the traditional method of post-harvest wintered maize stubbles without cover crops. Runoff and soil loss were monitored using enclosed erosion plots periodically sampled. Soil was tested for chemical parameters such as organic matter, organic carbon, total nitrogen, available phosphorus, and biological parameters such as microbial and fungal biomass, phospholipid fatty acid analysis and multiple substrates induced respiration. Additionally, during Experiment 2 easily available glomalin related soil proteins and aggregate stability were measured. Results showed a trend in the reduction of runoff and soil erosion. However, no significant differences were recorded. Overall, the impact of cover crops on soil microbiology was limited. Cover crops had a priming effect during Experiment 1 that led to a reduction of organic matter and organic carbon due to microbial activity. In Experiment 2 the relative abundance of fungi increased in the cover crop treatments. This was possibly due to the decrease of easily available nutrients and the increase of plant root debris, which are more available to fungi rather than bacteria. Cover crops seemed a practical option to improve the sustainability of maize production due to lack of an adverse impact on maize yield and the encouraging results on runoff, soil erosion and soil fungi. However, the effects were limited and further investigation is needed to prove the impact of cover crops in the long-term.
Open Access
Defining and quantifying the resilience of responses to disturbance: a conceptual and modelling approach from soil science
(Nature Publishing Group, 2016-06-22) Todman, Lindsay; Fraser, Fiona; Corstanje, Ronald; Deeks, Lynda K.; Harris, Jim A.; Pawlett, Mark; Ritz, Karl; Whitmore, A. P.
There are several conceptual definitions of resilience pertaining to environmental systems and, even if resilience is clearly defined in a particular context, it is challenging to quantify. We identify four characteristics of the response of a system function to disturbance that relate to “resilience”: (1) degree of return of the function to a reference level; (2) time taken to reach a new quasi-stable state; (3) rate (i.e. gradient) at which the function reaches the new state; (4) cumulative magnitude of the function (i.e. area under the curve) before a new state is reached. We develop metrics to quantify these characteristics based on an analogy with a mechanical spring and damper system. Using the example of the response of a soil function (respiration) to disturbance, we demonstrate that these metrics effectively discriminate key features of the dynamic response. Although any one of these characteristics could define resilience, each may lead to different insights and conclusions. The salient properties of a resilient response must thus be identified for different contexts. Because the temporal resolution of data affects the accurate determination of these metrics, we recommend that at least twelve measurements are made over the temporal range for which the response is expected.
Open Access
Distinct respiratory responses of soils to complex organic substrate are governed predominantly by soil architecture and its microbial community
(Elsevier, 2016-10-13) Fraser, Fiona; Todman, L. C.; Corstanje, Ronald; Deeks, Lynda K.; Harris, Jim A.; Pawlett, Mark; Whitmore, A. P.; Ritz, Karl
Factors governing the turnover of organic matter (OM) added to soils, including substrate quality, climate, environment and biology, are well known, but their relative importance has been difficult to ascertain due to the interconnected nature of the soil system. This has made their inclusion in mechanistic models of OM turnover or nutrient cycling difficult despite the potential power of these models to unravel complex interactions. Using high temporal-resolution respirometery (6 min measurement intervals), we monitored the respiratory response of 67 soils sampled from across England and Wales over a 5 day period following the addition of a complex organic substrate (green barley powder). Four respiratory response archetypes were observed, characterised by different rates of respiration as well as different time-dependent patterns. We also found that it was possible to predict, with 95% accuracy, which type of respiratory behaviour a soil would exhibit based on certain physical and chemical soil properties combined with the size and phenotypic structure of the microbial community. Bulk density, microbial biomass carbon, water holding capacity and microbial community phenotype were identified as the four most important factors in predicting the soils’ respiratory responses using a Bayesian belief network. These results show that the size and constitution of the microbial community are as important as physico-chemical properties of a soil in governing the respiratory response to OM addition. Such a combination suggests that the 'architecture' of the soil, i.e. the integration of the spatial organisation of the environment and the interactions between the communities living and functioning within the pore networks, is fundamentally important in regulating such processes.
Open Access
A DNA-barcode biodiversity standard analysis method (DNA-BSAM) reveals a large variance in the effect of a range of biological, chemical and physical soil management interventions at different sites, but location is one of the most important aspects determining the nature of agricultural soil microbiology
(Elsevier, 2023-07-06) Fernández-Huarte, Matías; Elphinstone, John G.; Adams, Ian P.; Vicente, Joana G.; Bhogal, Anne; Watson, Christine A.; Dussart, Francois; Stockdale, Elizabeth A.; Walshaw, John; McGreig, Sam; Simmons, Robert W.; Mašková, Lucie; Deeks, Lynda K.; Goddard, Matthew R.
There are significant knowledge gaps in our understanding of how to sustainably manage agricultural soils to preserve soil biodiversity. Here we evaluate and quantify the effects of agricultural management and location on soil microbiology using nine field trials that have consistently applied different soil management practices in the United Kingdom using DNA barcode sequence data. We tested the basic hypothesis that various agricultural management interventions have a significant and greater effect on soil bacterial and fungal diversity than geographic location. The analyses of soil microbial DNA sequence data to date has lacked standardisation which prevents meaningful comparisons across sites and studies. Therefore, to analyse these data and crucially compare and quantify the size of any effects on soil bacterial and fungal biodiversity between sites, we developed and employed a post-sequencing DNA-barcode biodiversity standard analysis method (DNA-BSAM). The DNA-BSAM comprises a series of standardised bioinformatic steps for processing sequences but more importantly defines a standardised set of ecological indices and statistical tests. Use of the DNA-BSAM reveals the hypothesis was not strongly supported, and this was primarily because: 1) there was a large variance in the effects of various management interventions at different sites, and 2) that location had an equivalent or greater effect size than most management interventions for most metrics. Some dispersed sites imposed the same organic amendments interventions but showed different responses, and this combined with observations of strong differences in soil microbiomes by location tentatively suggests that any effect of management may be contingent on location. This means it could be unreliable to extrapolate the findings of individual trials to others. The widespread use of a standard approach will allow meaningful cross-comparisons between soil microbiome studies and thus a substantial evidence-base of the effects of land-use on soil microbiology to accumulate and inform soil management decisions.
Open Access
Drainage models: an evaluation of their applicability for the design of drainage systems in arid regions
(Wiley, 2023-07-18) Ellafi, Murad; Simmons, Robert; Deeks, Lynda K.
Only 5%–10% of irrigated lands in least developed countries (LDCs) are currently drained. Although drainage simulation models (DSMs) are used to evaluate alternative designs, it is unclear which drainage model is suitable for LDCs' arid and semi-arid regions. This study evaluates selected DSMs (ADAPT, RZWQM2, DRAINMOD, EPIC, HYDRUS-1D, WaSim and SWAP) and critically assesses their applicability to arid and semi-arid areas. Also, establish and apply selection criteria based on the availability of data in LDCs with Libya as a case study, and identify the most suitable model for application in Libya. DRAINMOD had the highest overall score, and alternative methods to predict missing input parameters for DRAINMOD are discussed. Evaluating the feasibility of using predicted input parameters for DSMs to design drainage systems in LDCs would help farmers, planners and decision-makers to reduce the overall cost of drainage system and, also, make DRAINMOD a more accessible tool to evaluate different drainage designs.
Open Access
Evaluating agroecological farming practices
(DEFRA, 2023-02-20) Burgess, Paul J.; Redhead, John; Girkin, Nicholas T.; Deeks, Lynda K.; Harris, Jim A.; Staley, Joanna T.
There are a range of definitions for agroecologically-related farming systems and practices. In brief, organic farming places strong restrictions on inputs, agroecological analyses often focus on principles, and regenerative farming typically emphasises the enhancement of soil health and the diversity of agricultural and wild species at a farm-scale. Perhaps surprisingly the role of agroecological systems in reducing net greenhouse gas emissions from food and farming is implicit rather than explicit. Despite some literature contrasting agroecological and technical approaches, many authors indicate that the desirability of farming practices should be determined by their impact at the appropriate scale. Sustainable intensification has been defined as maintaining or enhancing agricultural production while enhancing or maintaining the delivery of other ecosystem services. Approaches such as the Global Farm Metric and LEAF Marque Certification can support the integrated assessment of 12 groupings of attributes at a farm-scale covering inputs and outputs, and environmental and social impacts. In this report we reviewed the following 16 practices: crop rotations, conservation agriculture, cover crops, organic crop production, integrated pest management, the integration of livestock to crop systems, the integration of crops to livestock systems, field margin practices, pasture-fed livestock systems, multi-paddock grazing, organic livestock systems, tree crops, tree-intercropping, multistrata agroforestry and permaculture, silvopasture, and rewilding.
Open Access
Evidence of ecological critical slowing-down in temperate soils
(EGU: European Geophysical Union, 2022-05-27) Fraser, Fiona; Corstanje, Ronald; Todman, Lindsay; Bello-Curás, Diana; Bending, Gary; Deeks, Lynda K.; Harris, Jim A.; Hilton, Sally; Pawlett, Mark; Zawadzka, Joanna; Whitmore, Andrew; Ritz, Karl
The resilience of ecological systems is crucially important, particularly in the context of climate change. We present experimental evidence of critical slowing-down arising from perturbation of a key function in a complex ecosystem, exemplified by soil. Different behavioural classes in soil respiratory patterns were detected in response to repeated drying:rewetting cycles. We characterised these as adaptive, resilient, fragile or non-resilient. The latter involved increasing erratic behaviour (i.e. increasing variance), and the propagation of such behaviour (i.e. autocorrelation), interpreted as a critical slowing-down of the observed function. Soil microbial phenotype and land-use were predominantly related to variance and autocorrelation respectively. No relationship was found between biodiversity and resilience, but the ability of a community to be compositionally flexible rather than biodiversity per se appeared to be key to retaining system function. These data were used to map the extent to which soils are close to crossing into alternative stable states at a national scale.
Open Access
Evidence Project Final Report: Evaluating the productivity, environmental sustainability and wider impacts of agroecological compared to conventional farming systems
(DEFRA, 2023-12-31) Burgess, Paul J.; Staley, Joanna T.; Hurley, Paul D.; Rose, David Christian; Redhead, John R.; McCracken, Morag E.; Girkin, Nicholas T.; Deeks, Lynda K.; Harris, Jim A.
Agriculture is a major cause of greenhouse gas (GHG) emissions, biodiversity loss, and pollution. Agroecological and regenerative farming have been advocated as alternative approaches that may have fewer negative (or even net positive) environmental impacts than conventional agriculture at farm- and landscape-scales, leading to considerable interest in these approaches (Newton et al. 2020; Bohan et al. 2022; Prost et al. 2023). This report forms the third part of a Defra-funded project Evaluating the productivity, environmental sustainability and wider impacts of agroecological and regenerative farming systems compared to conventional systems. The first part of this project was a rapid evidence review of agroecological and regenerative farming systems and their impacts (Burgess et al. 2023), and the second reported interview findings to examine farmer and stakeholder perspectives on barriers and enablers in agroecological and regenerative farming (Hurley et al. 2023). This third part of the project characterised the current research capability in agroecology and regenerative farming, and explored the potential role of a new ‘living lab’ trial network.
Open Access
A history of Soil Survey in England and Wales
(2012-04-24T00:00:00Z) Hallett, Stephen H.; Deeks, Lynda K.
Soil survey activities in England and Wales date back some 350 years, but systematic survey of our soils began only in the 1950s culminating in the activities of the Soil Survey of England and Wales.
Open Access
Impacts of long-term application of best management practices on yields and root carbohydrate content in asparagus (Asparagus officinalis) (UK)
(Elsevier, 2023-04-20) Mašková, Lucie; Simmons, Robert W.; Deeks, Lynda K.; De Baets, Sarah; Drost, Daniel T.
Yield physiology of asparagus (Asparagus officinalis L.) is strongly influenced by biotic factors such as crown and root rot caused by Fusarium spp. and by abiotic conditions such as precipitation or temperatures, duration of each harvest, and field management practices. Asparagus yields are linked to the availability of soluble carbohydrates (CHO) in the storage root system which is considered a key factor in asparagus productivity. The aim of this study was to quantify the impacts of the long-term application of a range of potential Best Management Practices (BMPs) on yield and storage root carbohydrate content in green asparagus in a long-term field trial. The trial was established in 2016 with the asparagus ‘Gijnlim’ variety. Commercial yields were collected in 2018, 2019 and 2020. Root carbohydrate content was determined in 2019 and 2020. BMPs included (1) companion crops - Rye (Secale cereale L.), Mustard (Sinapis alba L.), (2) interrow surface mulch applications of either straw mulch or PAS 100 compost (Publicly available specification) in combination with shallow soil disturbance (SSD), (3) the conventional practice and modifications of the conventional tillage practice by applying SSD or not applying SSD and (4) a zero-tillage option. Annual re-ridging (R) and not ridging (NR) were applied to BMP options 1–3. SSD had no significant impact on asparagus yields while annual re-ridging negatively affected total yields of treatments with bare soil interrows, which were managed without SSD. Conventional practice was associated with a 22% yield reduction and ∼€4250 ha−1 annual loss in potential revenue as compared to the Zero-tillage treatment. Companion cropping with mustard did not have a significant impact on asparagus yields. Rye without annual re-ridging was however associated with yield reductions of > 20% as compared to the Conventional practice. PAS 100 Compost applied in asparagus interrows (at 25 t ha−1 per year) in combination with SSD without annual re-ridging resulted in improvements to yields of 20%, 10% and 34% in 2018, 2019 and 2020, respectively, as compared to the Conventional practice. No correlation was observed between storage root soluble carbohydrate content and asparagus yields. The results of this study confirmed that asparagus yield, and thus total farm income can be significantly improved through implementation of several of the BMPs investigated.
Open Access
Improving soil and water management for agriculture: insights and innovation from Malta
(Malta College of Arts, Science & Technology, 2017-11-30) Hallett, Stephen; Sakrabani, Ruben; Thompson, Andrew; Deeks, Lynda K.; Knox, Jerry W.
Maltese soil resources are a precious and finite natural resource of great agricultural, environmental, and cultural value. They have been subject to human influence over a considerable time and, owing to prolonged intensive land use, have suffered from degradation by erosion, loss of organic matter, structural deterioration, and contamination from excess nitrates, agrochemicals, and salinity. Similarly, water resources (both quantity and quality) in Malta are also under severe stress owing to socio-economic development, over-abstraction for agricultural irrigation and from diffuse pollution. This paper briefly explores the key soil and water challenges facing farmers and the agricultural sector in Malta. Selected technology based and management innovations to improve resource use efficiency, sustain productivity, and support the agricultural sector are identified and discussed. The evidence forms part of FOWARIM ‘Fostering water-agriculture research and innovation in Malta’, an EC H2020-funded twinning project that is building research capacity, supporting knowledge exchange to practitioners, and providing evidence to inform policies for government and the agricultural sector in Malta.
Open Access
Indicators of soil quality - Physical properties (SP1611). Final report to Defra
(Defra, 2012-09-30) Rickson, R. Jane; Deeks, Lynda K.; Corstanje, Ronald; Newell-Price, Paul; Kibblewhite, Mark G.; Chambers, B.; Bellamy, Patricia; Holman, Ian P.; James, I. T.; Jones, Robert; Kechavarsi, C.; Mouazen, Abdul; Ritz, K.; Waine, Toby
The condition of soil determines its ability to carry out diverse and essential functions that support human health and wellbeing. These functions (or ecosystem goods and services) include producing food, storing water, carbon and nutrients, protecting our buried cultural heritage and providing a habitat for flora and fauna. Therefore, it is important to know the condition or quality of soil and how this changes over space and time in response to natural factors (such as changing weather patterns) or to land management practices. Meaningful soil quality indicators (SQIs), based on physical, biological or chemical soil properties are needed for the successful implementation of a soil monitoring programme in England and Wales. Soil monitoring can provide decision makers with important data to target, implement and evaluate policies aimed at safeguarding UK soil resources. Indeed, the absence of agreed and well-defined SQIs is likely to be a barrier to the development of soil protection policy and its subsequent implementation. This project assessed whether physical soil properties can be used to indicate the quality of soil in terms of its capacity to deliver ecosystem goods and services. The 22 direct (e.g. bulk density) and 4 indirect (e.g. catchment hydrograph) physical SQIs defined by Loveland and Thompson (2002) and subsequently evaluated by Merrington et al. (2006), were re-visited in the light of new scientific evidence, recent policy drivers and developments in sampling techniques and monitoring methodologies (Work Package 1). The culmination of these efforts resulted in 38 direct and 4 indirect soil physical properties being identified as potential SQIs. Based on the gathered evidence, a ‘logical sieve’ was used to assess the relative strengths, weaknesses and suitability of each potential physical SQI for national scale soil monitoring. Each soil physical property was scored in terms of: soil function – does the candidate SQI reflect all soil function(s)? land use - does the candidate SQI apply to all land uses found nationally? soil degradation - can the candidate SQI express soil degradation processes? does the candidate SQI meet the challenge criteria used by Merrington et al. (2006)?This approach enabled a consistent synthesis of available information and the semi-objective, semi-quantitative and transparent assessment of indicators against a series of scientific and technical criteria (Ritz et al., 2009; Black et al., 2008). The logical sieve was shown to be a flexible decision-support tool to assist a range of stakeholders with different agenda in formulating a prioritised list of potential physical SQIs. This was explored further by members of the soil science and soils policy community at a project workshop. By emphasising the current key policy-related soil functions (i.e. provisioning and regulating), the logical sieve was used to generate scores which were then ranked to identify the most qualified SQIs. The process selected 18 candidate physical SQIs. This list was further filtered to move from the ‘narrative’ to a more ‘numerical’ approach, in order to test the robustness of the candidate SQIs through statistical analysis and modelling (Work Package 2). The remaining 7 physical SQIs were: depth of soil; soil water retention characteristics; packing density; visual soil assessment / evaluation; rate of erosion; sealing; and aggregate stability. For these SQIs to be included in a robust national soil monitoring programme, we investigated the uncertainty in their measurement; the spatial and temporal variability in the indicator as given by observed distributions; and the expected rate of change in the indicator. Whilst a baseline is needed (i.e. the current state of soil), it is the rate of change in soil properties and the implications of that change in terms of soil processes and functioning that are key to effective soil monitoring. Where empirical evidence was available, power analysis was used to understand the variability of indicators as given by the observed distributions. This process determines the ability to detect a particular change in the SQI at a particular confidence level, given the ‘noise’ or variability in the data (i.e. a particular power to detect a change of ‘X’ at a confidence level of ‘Y%’ would require ‘N’ samples). However, the evidence base for analysing the candidate SQIs is poor: data are limited in spatial and temporal extent for England and Wales, in terms of a) the degree (magnitude) of change in the SQI which significantly affects soil processes and functions (i.e. ‘meaningful change’), and b) the change in the SQI that is detectable (i.e. what sample size is needed to detect the meaningful signal from the variability or noise in the signal). This constrains the design and implementation of a scientifically and statistically rigorous and reliable soil monitoring programme. Evidence that is available suggests that what constitutes meaningful change will depend on soil type, current soil state, land use and the soil function under consideration. However, when we tested this by analysing detectable changes in packing density and soil depth (because data were available for these SQIs) over different land covers and soil types, no relationships were found. Schipper and Sparling (2000) identify the challenge: “a standardised methodology may not be appropriate to apply across contrasting soils and land uses. However, it is not practical to optimise sampling and analytical techniques for each soil and land use for extensive sampling on a national scale”. Despite the paucity in data, all seven SQIs have direct relevance to current and likely future soil and environmental policy, because they can be related (qualitatively) to soil processes, soil functions and delivery of ecosystem goods and services. Even so, meaningful and detectable changes in physical SQIs may be out of time with any soil policy change and it is not usually possible to link particular changes in SQIs to particular policy activities. This presents challenges in ascertaining trends that can feed into policy development or be used to gauge the effectiveness of soil protection policies (Work Package 3). Of the seven candidate physical SQIs identified, soil depth and surface sealing are regarded by many as indicators of soil quantity rather than quality. Visual soil evaluation is currently not suited to soil monitoring in the strictest sense, as its semi-qualitative basis cannot be analysed statistically. Also, few data exist on how visual evaluation scores relate to soil functions. However, some studies have begun to investigate how VSE might be moved to a more quantified scale and the method has some potential as a low cost field technique to assess soil condition. Packing density requires data on bulk density and clay content, both of which are highly variable, so compounding the error term associated with this physical SQI. More evidence is needed to show how ‘meaningful’ change in aggregate stability affects soil processes and thus soil functions (for example, using the limited data available, an equivocal relationship was found with water regulation / runoff generation). The analysis of available data has given promising results regarding the prediction of soil water retention characteristics and packing density from relatively easy to measure soil properties (bulk density, texture and organic C) using pedotransfer functions. Expanding the evidence base is possible with the development of rapid, cost-effective techniques such as NIR sensors to measure soil properties. Defra project SP1303 (Brazier et al., 2012) used power analyses to estimate the number of monitoring locations required to detect a statistically significant change in soil erosion rate on cultivated land. However, what constitutes a meaningful change in erosion rates still requires data on the impacts of erosion on soil functions. Priority cannot be given amongst the seven SQIs, because the evidence base for each varies in its robustness and extent. Lack of data (including uncertainty in measurement and variability in observed distributions) applies to individual SQIs; attempts at integrating more than one SQI (including physical, biological and chemical SQIs) to improve associations between soil properties and processes / functions are only likely to propagate errors. Whether existing monitoring programmes can be adapted to incorporate additional measurement of physical SQIs was explored. We considered options where one or more of the candidate physical SQIs might be implemented into soil monitoring programmes (e.g. as a new national monitoring scheme; as part of the Countryside Survey; and as part of the National Soil Inventory). The challenge is to decide whether carrying out soil monitoring that is not statistically robust is still valuable in answering questions regarding current and future soil quality. The relationship between physical (and other) SQIs, soil processes and soil functions is complex, as is how this influences ecosystem services’ delivery. Important gaps remain in even the realisation of a conceptual model for these inter-relationships, let alone their quantification. There is also a question of whether individual quantitative SQIs can be related to ecosystem services, given the number of variables.
Open Access
Long-term impacts of repeated cover cropping and cultivation approaches on subsoil physical properties
(Elsevier, 2023-06-02) Martlew, J.; Wilfred, Otten; Morris, N.; De Baets, S.; Deeks, Lynda K.
The intensification of arable agriculture has resulted in an increase in vehicle wheel load and the intensity of field operations, which has increased the risk and incidence of degradation in physical properties of the uncultivated subsoil layer. Biopores generated by the long-term, repeated use of specific cover crops within an arable rotation has been suggested as an approach to improve subsoil physical properties. Therefore, this paper aimed to determine the impact of long-term repeated cover cropping and the interaction of rotation treatments with different cultivation approaches on subsoil physical properties. Data was collected at the NIAB ‘Sustainable Trial for Arable Rotations’ long-term, rotation and cultivation field experiment established in 2006. Rotation treatments comprised a brassica cover crop alternated annually with winter wheat (ALTCC) compared to continuous winter wheat (CWW). Cultivation treatments comprised PLOUGH (250 mm depth), and non-inversion cultivation at 250 mm (DEEP) and 100 mm (SHALLOW) depths. Penetration resistance and volumetric soil moisture were collected at bi-monthly intervals during the 2018/19 growing season. Undisturbed soil cores were collected for laboratory analyses of soil water retention, water stable aggregates, root morphology digital scanning and biomass, and X-ray computed tomography (CT). Results showed that treatment ALTCC combined with SHALLOW, resulted in lower penetration resistance and increased moisture in the subsoil. This increased subsoil moisture persisted later into the season compared to the control. SHALLOW increased subsoil water retention, improved subsoil root morphology and increased subsoil porosity. Benefits from treatment ALTCC were not observed where combined with higher intensity, deeper cultivation. Overall, the combination of treatments ALTCC with SHALLOW, produced significant benefits to subsoil physical properties.
Open Access
On the origin of carbon dioxide released from rewetted soils
(Elsevier, 2016-07-06) Fraser, Fiona; Corstanje, Ronald; Deeks, Lynda K.; Harris, Jim A.; Pawlett, Mark
When dry soils are rewetted a pulse of CO2 is invariably released, and whilst this phenomenon has been studied for decades, the precise origins of this CO2 remain obscure. We postulate that it could be of chemical (i.e. via abiotic pathways), biochemical (via free enzymes) or biological (via intact cells) origin. To elucidate the relative contributions of the pathways, dry soils were either sterilised (double autoclaving) or treated with solutions of inhibitors (15% trichloroacetic acid or 1% silver nitrate) targeting the different modes. The rapidity of CO2 release from the soils after the drying:rewetting (DRW) cycle was remarkable, with maximal rates of evolution within 6 min, and 41% of the total efflux over 96 h released within the first 24 h. The complete cessation of CO2 eflux following sterilisation showed there was no abiotic (dissolution of carbonates) contribution to the CO2 release on rewetting, and clear evidence for an organismal or biochemical basis to the flush. Rehydration in the presence of inhibitors indicated that there were approximately equal contributions from biochemical (outside membranes) and organismal (inside membranes) sources within the first 24 h after rewetting. This suggests that some of the flux was derived from microbial respiration, whilst the remainder was a consequence of enzyme activity, possibly through remnant respiratory pathways in the debris of dead cells.
Open Access
Optimising polyacrylamide (PAM) spray application to mitigate the agronomic effects of Soil Crust.
(Cranfield University, 2022-07) Arpano, Silvia; Simmons, Robert W.; Deeks, Lynda K.
The Leafy greens industry provides micronutrient-rich fresh produce at an affordable price. To meet the demand, multiple short crop cycles per year are seeded and harvested, for example, the summer spinach cycle can be as short as 21 days with 4 to 6 crop cycles in a season, in the UK. However, this high input/output agronomic system has a negative impact on other provisioning and regulating ecosystem services (ES). The primary soil-related ES that are affected are sequestration of soil carbon, crop production and water storage. The intensive soil management strategy promotes on-field loss of soil organic matter, which reduces soil resilience to erosive forces and contributes to the formation of capping and sealing. Soil capping and sealing inhibits seedling emergence, which reduces crop productivity. Within the rapid management cycle of leafy greens production there is limited time to incorporate soil amendments to offset the loss of SOM. This research explores the use of polyacrylamides (PAMs) as a soil surface amendment within this cropping system. Polyacrylamides are molecules with a long carbon backbone characterised by areas of different electric charge density. This trait allows them to bind to polar substance (e.g. water, soil colloids, soils organic matter). They are excellent flocculants and have been used for decades in furrow-irrigated crops to mitigate soil erosion and increase water infiltration. Besides flocculating particles in free-flowing water, PAMs have also been found to bind and protect soil aggregates by being adsorbed into aggregates and stabilising them. In combination, these two properties of PAMs have the potential to mitigate the agronomic effects of soil capping and sealing, including reducing emergence impedance, reducing splash contamination, and promoting water infiltration. However, PAMs are very hygroscopic and can be difficult to work with at concentrations above 500 ppm in water. This research investigated a new PAM broadcast system, using a Dual-Fluid nozzle which mixes PAM and water outside of the hydraulic system. The effect of PAMs on soil and crops were measured in a laboratory experiment and in five field trials on two crops, coriander and spinach. The metrics measured included soil crust, soil moisture, emergence and final yield quantity and quality. The results of the research have shown the efficacy of PAM within commercial leafy greens crops. The application of PAM was associated with earlier emergence in coriander, that lead to higher biomass per plant and it also increased the emergence count in spinach, leading to an overall higher yield (47- 39% for plots treated with 80 kg ha⁻¹ of PAM and 80kg ha⁻¹ PAM+Ca respectively). The amount of soil splash, and therefore potential for contamination of the product, was also reduced (24, 41 and 59% decrease in splash detached soil from plots treated with 40, 80 and 120 kg ha⁻¹ PAM respectively compared to the control). An economic appraisal based on the field data, also determined that PAM could be economically viable within the commercial cropping system and identified future improvements.