CERES :: Browsing by Author "Simmons, Robert W."

Browsing by Author "Simmons, Robert W."

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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
Application of organic amendments to restore soil health and productivity of a degraded soil.
(2017-04) Unagwu, Benedict Onyebuchi; Simmons, Robert W.; Rickson, R. Jane;
Organic amendments (OAs) have the capacity to enhance physical, chemical, biological soil quality indicators (SQIs) and to improve soil productivity. This study investigated the effects of different OAs (Mushroom Compost, MC; PAS-100 compost, PAS; Anaerobic Digestate Solid Waste, AD_SW; and Poultry Manure, PM), applied at 10 t ha⁻¹ and 30 t ha⁻¹ with or without inorganic fertilizer (applied at 50% of the RB209 recommended rates for maize) on key SQIs, soil health and plant performance on a degraded sandy loam soil. The treatments were laid out in a greenhouse using a completely randomized design and replicated four times. The soil and OAs were thoroughly mixed and incubated for two weeks. Thereafter, composite 3-point soil samples were taken from each treatment replicate for post-incubation (POI) soil analysis. Maize (Zea mays, Severus variety), was used to assess the impact of the OAs on plant performance. Plant height, number of plant leaves and stem diameter were measured weekly. Post-harvest (POH) composite 3-point soil samples were again taken for soil analysis. The data generated from POI and POH laboratory analyses and plant measurements were subjected to analysis of variance (ANOVA) followed by post-hoc Fisher LSD analysis at 5% probability level. At POI, the OAs had 22-44.5% higher water holding capacity [WHC], increased porosity and reduced bulk density [BD] as compared with the un-amended control treatment (CNF). The results indicate that 1% increase in soil organic matter (SOM) increased the Available Water Content (AWC) by 5.31 g g⁻¹ while reducing the BD by 1 g cm⁻¹ and increasing the soil Water Content at Field Capacity (WCFC) by 36.5 g g⁻¹ . The Olsen-P, Available-K, Available-Mg, Total-N, and microbial biomass C [MBC] associated with the OA treatments were significantly higher as compared with CNF treatment. At POH, across application rates, OA treatments with or without inorganic fertilizer addition had >15% higher (p <0.05) WHC [WCFC], 40% higher porosity and 55% lower BD as compared with CNF treatment. For both POI and POH, higher rates (30 t ha⁻¹ ) of OAs with or without inorganic fertilizer addition had higher (p <0.05) effects on the water release characteristics [WCFC, EAW, AWC] than lower (10 t ha⁻¹ ) rates of OAs. At POH, across application rates, the OA treatments increased the Olsen-P, SOM, Total-C, and TOC by over 37, 23, 75 and 81%, respectively, relative to CNF. Across application rates with or without inorganic fertilizer addition, the OA treatments did not significantly affect the CEC as compared with CNF. The OAs increased the P, K and Mg indices relative to the CNF which increased with increase in OA application rates. Further, the OA treatments increased the MBC by 72-95% (p <0.05) and reduced microbial stress by over 30% relative to CNF. Without inorganic fertilizer addition, the OA treatments increased the above ground and below ground plant biomass (AGDB and BGDB) by 24-65% and 38-88% respectively, compared with the CNF treatment except for the PAS treatments. The OAs had 100% increases in cob yield as compared with CNF, except for PAS1NF/2NF and AD_SW1NF treatments. Inorganic fertilizer addition had marked effects on plant performance, particularly when combined with the PAS OA. The study concludes that application of OAs has the potential to improve soil health and productivity of a degraded sandy loam soil. Long term effects of these OAs merit further detailed exploration.
Open Access
Assessment of an innovative soil aerator on soil physical disturbance and reducing runoff on compacted grassland
(Cranfield University, 2009-09) Shanahan, Peter; Simmons, Robert W.; Hann, M. J.
Poor grassland management practices increases compaction and reduces infiltration leading to increasing risk of poaching and runoff generation. On-site impacts of grassland compaction include the loss of topsoil structure which also reduces soil ecosystem functioning. In addition, ongoing diffuse water pollution from compacted grassland limits the ability of the UK’s authorities to meet EU water quality guidelines such as the Water Framework Directive and address flood risks in areas of extensive grassland management (e.g. Boscastle, 2004). This study investigates the effects of an innovative ground-driven rotary soil aerator at alleviating soil compaction and reducing overland flow (designed by Mr. Roger Clay, Herefordshire). The magnitude of soil disturbance from slotting was assessed at the Cranfield University Soil Dynamics Test Centre soil-bin. Draught and vertical force requirements and tillage efficiency were also determined for varying depth and horizontal and vertical angle combinations using an Extended Octagonal-Ring Transducer (EORT). The effect of various slotting treatments on runoff was then investigated on a steep compacted permanent pasture in Herefordshire using erosion plots and simulated rainfall. From the soil-bin assessment, soil disturbance was most efficient (lowest specific draught) at 100 mm depth, a vertical angle of 18° and with increasing horizontal angle (0° to 10°). The draught requirement for a single bladed disc at 18° vertical ranged from 0.88 to 1.24 kN (90-126 kg force) and a maximum vertical force or ballast requirement of 257 kg force per bladed disc. Slotting treatments reduced runoff by 75% as compared with the non-slotted control.
Open Access
Assessment of silt from sand and gravel processing as a suitable sub-soil material in land restoration: A glasshouse study
(Elsevier, 2018-12-01) Mašková, Lucie; Simmons, Robert W.; De Baets, Sarah; Montero, Moran; Delmer, Aude; Sakrabani, Ruben
Annually, sand and gravel processing generates approximately 20 million tonnes of non-commercial by-product as fine silt particles (<63 μm) which constitutes approximately 20% of quarry production in the UK. This study is significant as it investigated the use of quarry silt as a sub-soil medium to partially substitute soil-forming materials whilst facilitating successful post-restoration crop establishment. In a glasshouse pot experiment, top-soil and sub-soil layering was simulated, generating an artificial sub-soil medium by mixing two quarry non-commercial by-products, i.e. silt and overburden. These were blended in three ratios (100:0, 70:30, 50:50). Pots were packed to two bulk densities (1.3 and 1.5 g cm-3) and sown with three cover crops used in the early restoration process namely winter rye (Secale cereale), white mustard (Sinapis alba) and a grassland seed mixture (Lolium perenne, Phleum pratense, Poa pratensis, Festuca rubra). Three weeks into growth, the first signs of nitrogen (N) deficiency were observed in mustard plants, with phosphorus (P) and potassium (K) deficiencies observed at 35 days. Rye exhibited minor N deficiency symptoms four weeks into growth, whilst the grassland mixture showed no deficiency symptoms. The 70:30 silt:overburden sub-soil blend resulted in significantly higher Root Mass Densities of grassland seed mixture and rye in the sub-soil layer as compared with the other blends. The innovation in this work is the detailed physical, chemical and biological characterisation of silt:overburden blends and effects on root development of plants commonly used in early restoration to bio-engineer soil structural improvements.
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
Controlling soil erosion in a changing climate: evaluating suitable plant species in grassed waterway design.
(2022-04) Lees, Corina; Simmons, Robert W.; Rickson, R. Jane
Soil erosion is a global problem which needs mitigating due to the on-site and off- site impacts it causes. Soil erosion is set to become an even greater problem due to climate change. Climate change is likely to increase the intensity, frequency and duration of precipitation events. This change in precipitation will increase flow erosivity and thus increase the chance of soil detachment. Grass-based erosion mitigation features will have to be able to withstand a higher volume of water as runoff volumes will increase due to climate change. An increased surface runoff rate will increase sediment transport capacity leading to more soil erosion when coupled with an increased detachment rate therefore solutions for the future need to be researched. Grass-based erosion mitigation features such as swales, buffer strips and grassed water ways (GWWs) have been shown to be effective. In this study, Festulolium Bx511 (F2), Festulolium cv Prior (F1) and a mixture of Festuca rubra and Lolium perenne (C) were used in mixtures and monocultures to investigate their efficacy in mitigating erosion. Experiment 1 used growth rooms under different climatic conditions, a summer scenario (22°C) and an autumn scenario (15°C). There were also different rainfall scenarios, drought (No rainfall), normal (100 % rainfall based on average rainfall (1981 – 2010) average rainfall (1981 – 2010) data from the Met Office) and excess (200 % of average rainfall (1981 – 2010) based on data from the Met Office) to see how they would affect the plant traits needed for erosion control. For summer establishment conditions the normal rainfall value was 49.2 mm, and the excess rainfall was 98.4 mm. For autumn establishment conditions the normal rainfall was 81.9 mm, and the excess value was 163.8 mm. A plant trait ranking system was devised, the species which showed promise were taken forward and used within hydraulic flume experiments to assess actual soil erosion mitigation potential. Plant traits linked to erosion control include both above ground (% cover, plant height, number of stems, number of tillers, stem diameter (mm), stem area density (mm² mm-²), above ground biomass (g) and below ground traits (root total length (cm), root total surface area (cm² ), root diameter (mm) and total root length (cm) of ≤0.25 mm diameter. Climate change is likely to change how grass plant traits are manifest due to the differing climatic conditions. Therefore, any solutions currently promoted that utilise grass monocultures and mixtures for erosion mitigation features such as GWWs may need to be revised to mitigate for climate change. Conclusions from Experiment 1 include that species selection for soil erosion control features such as GWWs must consider potential rainfall and temperature conditions during the grass establishment for optimal erosion control. There were, however, two species combinations which could be considered as year-round candidates, Fest_1+Fest_2+C and C. Experiment 2 was a hydraulic flume experiment where the inflow rates used were 0.2 – 1.4 l s¯¹. Significant differences in the following plant traits; number of stems, number of tillers, stem diameter (mm), stem area density (mm² mm-²), total root length (≤0.25 mm ⌀), total root surface area (cm ² ), and root diameter (mm) were observed between different treatments. Conv had a significantly higher number of stems as compared to all other experimental treatments. Fest_1 had a significantly higher number of tillers, stem diameter and stem area density as compared to all other treatments. Fest_1+Fest_2+C had a significantly higher total root length (≤0.25 mm ⌀) as compared to Conv. Fest_1+2 had a significantly higher total root surface area than the Fest_1 and Fest_1+Fest_2+C experimental treatments. Fest_1+Fest_2 had a significantly higher root diameter as compared to the Fest_1+Fest_2+C experimental treatment. However, significant differences did not manifest in sediment concentration. In conclusion, it did not matter if grass species monocultures or mixtures were used as there were no significant differences in sediment concentration between the experimental grass treatments. Experiment 3 was also a hydraulic flume experiment where the inflow rates used were 0.2 – 2.6 l s¯¹. In this experiment there was a lowered seeding rate (L) and a recommended seeding rate used (N). There were significant differences in plant traits and also in sediment concentration. The critical thresholds for the Environment Agency (EA) major event classification of 1000 mg l¯¹ to be reached were determined for Experiment 3. There were several experimental grass treatments which did not breach the limit set out by the EA (Conv N, Fest_1+2 L, Fest_1 N and Conv L). In conclusion the Conv L, Fest_1 N and Fest_1+2 L species treatments should be recommended for farmers for use in soil erosion mitigation features such as grassed waterways. This thesis was made possible thanks to the soils training and research studentship centre for doctoral training (STARS CDT). It was funded by Biotechnology and Biological Sciences Research Council (BBSRC) and Natural Environment Research Council (NERC), Grant/Award Number: NE-R010218-1.
Open Access
Critical evaluation of compost erosion control blankets (CECBs) against conventional best management practices (BMPs) for the prevention and control of soil erosion, nutrient loss and storm water runoff from engineered slopes under simulated UK conditions
(Cranfield University, 2010-03) Mantovani, Dario; Simmons, Robert W.
In recent decades increasing attention has been dedicated to issues of sustainable land management. Soil is essential for a number of functions and services which are central to the sustainability of agro-ecosystems and the global economy. Consequently soil management and specifically soil erosion including, erosion from construction activities, is moving up the political and legislative agenda. This thesis investigated the suitability of Compost Erosion Control Blankets (CECBs) for runoff and erosion control, on construction sites under two simulated rainfall events (5 and 75 year return period storm events (PRSE)) as compared with currently adopted Best Management Practices (BMPs). Two grades of BSI BSI PAS 100:2005 compost, namely CECB0-20mm and CECB0-40mm, were tested against two Erosion Control Blankets (ECBs), namely ECBstraw and ECBcoir, and control bare soil plots. Treatment performance was evaluated in terms of a range of attributes including runoff rate, volume and time to runoff initiation and total suspended solid TSS and nitrogen and phosphorous levels in runoff. In addition, nitrogen and phosphorous levels in leachate were also investigated.
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
Do cover crops give short term benefits for soil health?
(Association of Applied Biologists, 2018-12-31) Storr, Tom; Simmons, Robert W.; Hannam, Jacqueline A.
Cover crop use in the UK is increasing with establishment often before spring cereal crops. Therefore trials were implemented to assess two different cover crop mixtures for i) their ability to remediate soil compaction, ii) aid water management and iii) increase earthworm numbers. Two cover crop mixtures; frost sensitive (black oats, oil radish and mustard) and winter hardy (forage rye, oil radish and berseem clover) were compared to control plots. This replicated trial was based at G’s Growers on an organo-mineral soil with a cover crop sown between wheat harvested in August 2016 and maize sown in May 2017. The results suggest that in the short term there are small differences in soil physical characteristics. Notably at a depth of 10–20 cm there is a reduction in soil strength as measured by the penetrologger and shear vane following the frost sensitive cover crop mix. Juvenile earthworm population was significantly greater in the control treatment compared to the frost sensitive cover crop treatment. In May 2017 maize was established across all plots.
Open Access
The effect of cover crops on soil quality indicators in a cereal and salad rotation.
(2019-01) Storr, Tom; Hannam, Jacqueline A.; Simmons, Robert W.
Cover crop (CC)s influence soil function and thus affect crop yield and ecosystem services provided by soil. CCs are a relatively new soil management practice in U.K. agriculture, but are gaining in popularity amongst farmers. However, research on the effect of CCs on soil function in the short term and how to manage CCs effectively in the U.K. is limited. Therefore, field trials investigated the effect of CCs on physical (visual evaluation of soil structure, penetration resistance, bulk density, soil shear strength and soil moisture), chemical (total organic carbon and soil available nitrogen) and biological (earthworm abundance, microbial biomass and diversity) soil quality indicators, as well as crop yield. CCs were established between wheat and forage maize. A companion crop established with the maize remained overwinter after maize harvest until lettuce establishment the following spring. CCs placed between wheat and maize only affected available soil nitrogen with limited significant effects on other soil quality indicators. The addition of a companion crop significantly improved earthworm abundance, microbial community diversity and biomarkers associated with fungi. The companion crop significantly reduced bulk density and soil shear strength at 0.05 and 0.15m, respectively as well as penetrative resistance at 0-0.03m depth. Thus, continued plant presence, achieved through the establishment of cover and companion crops in the rotation allows for the accumulation of positive effects on soil quality and function in a short period of time (20months). Additionally, a survey distributed to U.K. farmers (n = 117) provided an understanding of the use, management and challenges associated with CCs. Respondents reported that the Basic Payment Scheme supporting CC use is not suitable and could be more flexible. Additionally, it took >3 years to realise benefits to soil structure. The knowledge gained from the survey can be used to inform future research and policy so that CCs can be implemented effectively to benefit the ecosystem services provided to the farmer and wider community.
Open Access
Effects of cutting length and bud removal on root yield and starch content of cassava under rainfed conditions
(Cambridge University Press, 2017-03-27) Prasitsarn, Mapita; Polthanee, Anan; Trelo-ges, Vidhaya; Simmons, Robert W.
Bud removal of the cuttings at underground level has been claimed by cassava growers in Thailand as a method to increase cassava yield. This practise should be tested experimentally to explain the reason for yield increase. The objective of this study was to investigate the effects of bud removal and cutting length on storage root yield and starch content of three cassava varieties. Field experiment was conducted in a split–split plot design with four replications in 2010 and 2011, under rainfed conditions. Three cassava varieties (KU50, RY9 and HB60) were assigned as main plot. Two cutting lengths (15 cm and 30 cm) were assigned as sub plots, and two treatments of buds (buds cut and not cut) were assigned as sub–sub plots. The buds on the cuttings that were inserted into the soil were removed. In 2010, the plants from 15-cm long cuttings subjected to bud removal had higher fresh storage root yield (88.4 Mg ha−1) than did plants from 30-cm long cuttings subjected to bud removal (75.8 Mg ha−1). Cutting of buds also had higher fresh storage root yield (89.1 Mg ha−1) than did non bud-cutting (75.0 Mg ha−1). KU50 had the highest fresh storage root yield (91.4 Mg ha−1), dry root yield (48.4 Mg ha−1) and starch yield (20.1 Mg ha−1). Cutting length of 15 cm had higher starch concentration in storage roots (25.6%) than did cutting length of 30 cm (24.2%). HB60 had the highest starch concentration (27.0%) among cassava varieties tested. The data in 2011 were similar to the data in 2010. The responses of varieties to bud removal and cutting length are discussed.
Open Access
Efficacy of mulch and tillage options to reduce runoff and soil loss from asparagus interrows
(Elsevier, 2020-04-01) Niziolomski, Joanna C.; Simmons, Robert W.; Rickson, R. Jane; Hann, Mike J.
In the UK, conventional asparagus cultivation practices on sloping land, erodible soils and increased frequency of extreme rainfall events combine to promote runoff generation and soil loss, particularly from interrows. This instrumented field study investigated the interactive effect of mulch and shallow soil disturbance (working depth of 0.175 m) on reducing runoff and soil loss. Ten treatments were installed in a commercial asparagus field near Ross-on-Wye (England, UK) during May 1st–July 17th, 2012. Straw and compost were applied to the interrows at high and low application rates (straw = 5 t ha−1 and 3 t ha−1 and compost = 18 t ha−1 and 8 t ha−1, respectively), both with or without shallow soil disturbance (SSD and Non-SSD) as compared with a bare soil, unamended Control. Across five sampling periods, Non-SSD straw mulch applied at 5 t ha−1 and 3 t ha−1; Non-SSD compost mulch at 18 t ha−1; and straw mulch applied at 5 t ha−1 with SSD all significantly reduced cumulative total soil loss by 53–72% as compared with the Control. Further, mulch treatments with SSD were in general less effective at reducing total soil loss as compared to non-SSD mulch treatments. Compost application was less effective than straw, due to sub-optimal compost blanket depths as dictated by N restrictions for Nitrate Vulnerable Zones, in which the study took place. Despite an overall reduction in total soil loss of 72% (associated with Non-SSD straw mulch applied at 5 t ha−1), soil erosion rates exceeded 1.4 t ha−1 yr−1, considered to be a tolerable erosion rate in the EU. In addition, measured sediment concentrations in the runoff consistently exceeded the EU water quality guideline value of 25 mg l−1. The results indicate that the efficacy of the treatments tested was not adequate to reduce soil erosion in commercial asparagus fields in the UK to tolerable rates. This may in large part be due to daily foot trafficking events that occur during the asparagus harvesting period (April–June) which disturbs and degrades the treatments applied reduing their efficacy. This study demonstrates that additional research is required in order to identify effective erosion control measures to ensure the sustainability of commercial asparagus production systems in the UK
Open Access
Efficacy of selected phosphorous sorbing materials (PSMs) to enhance the orthophosphate sorption capacity of filter socks
(Wiley, 2020-11-18) Cooke, A. L.; Simmons, Robert W.; Rickson, R. Jane; Sakrabani, Ruben
Agricultural phosphate (PO43‐) is a major cause of water quality compliance failures. Filter socks (FS) are a sediment‐control method proven to be effective at removing sediment and sediment bound‐P. Within the water and wastewater treatment industries phosphorous sorbing materials (PSMs) are widely used to remove reactive PO43‐. Combining PSMs with FS provides an opportunity to concomitantly remove sediment, sediment bound‐P and PO43‐ from agricultural runoff. A column experiment was undertaken to evaluate the efficacy of selected PSMs to remove PO43‐ across a range of PO43‐ concentrations (0.08, 0.26 and 1.3 mg/l) and contrasting FS fill media (PAS 100 Compost and Woodchip). The results indicate that Ca‐enriched ferrihydrite removed up to 99% of PO43‐, and was the only PSM to reduce PO43‐ to below the target value of <0.05 mg/l. An initial cost benefit analysis indicates that PSM‐enhanced FS are a viable option to remove PO43‐ from agricultural runoff.
Open Access
Filter socks to mitigate sediment, sediment-bound phosphate and orthophosphate losses, from arable lands under extreme rainfall events.
(2018-02) Cooke, Alexandra; Simmons, Robert W.; Rickson, R. Jane; Sakrabani, Ruben
Agricultural diffuse pollution is a major environmental issue within the UK. Within England alone, sediment and phosphates in agricultural runoff account for 2967 rivers failing their Water Framework Directive (WFD) water quality targets. Effective end-of-pipe solution sediment control measures include silt fences, buffer strips and berms. However, with the exception of buffer strips, these are not widely used in agricultural lands. Furthermore in terms of extreme rainfall events, their long-term efficacy is limited or unproven, as well as their ability to also remove orthophosphate. Filter socks (FS) are widely used as construction site sediment control within the USA, and could provide another mitigation option; however there has been limited testing for a UK environment, and their current fill media does not aid orthophosphate removal. Phosphorus sorbing materials (PSMs) are widely used within the wastewater treatment industry to remove orthophosphate. This research evaluated the efficacy of PSM amended FS to concurrently remove sediment, sediment-bound phosphate, and orthophosphate. In Phase 1, FS were evaluated in terms of their sediment removal ability, with and without a proprietary PSM, under UK agricultural field conditions. Runoff and eroded sediment was collected from erosion plots under a maize cropping regime. The 9-month replicated field trial results indicated variable results. The fill media produced an initial release of fines and orthophosphate after installation, although this declined over time. This flush event significantly increased the amount of sediment and orthophosphate found within the runoff of the FS compared to the runoff from the control, in sampling period 1. By the last sampling period, irrespective of fill-media (Woodchip or PAS 100 Compost), FS reduced runoff sediment load compared to the non-FS control. Orthophosphate removal was not increased by the addition of the proprietary PSM. Consequently a range of alternative PSMs were evaluated in Phase 2. Alternative PSMs were identified from a literature review. Their ability to remove orthophosphate was established through a fully replicated column experiment over a range of orthophosphate concentrations (0.08 – 1.30 mg P l⁻¹). The results indicate that ferrihydrite and goethite ochres were significantly more effective than all other treatments, with orthophosphate removal efficiencies ranging from 51 – 99 % and 32 –94 %, respectively. Furthermore the ferrihydrite ochre was the only PSM to reduce the orthophosphate concentration to below that of the water quality target for the Lugg river catchment (0.05 mg P l⁻¹). As the most effective PSMs, these were taken forward to Phase 3 where PSM amended FS were assessed for concurrent sediment, sediment-bound phosphate and orthophosphate removal under simulated laboratory experiments. Efficacy and performance was established across a series of replicated laboratory experiments using a rainfall-runoff simulator. These incorporated extreme rainfall events (80 mm hr⁻¹ intensity, 5 - 25 min duration), representing return periods of 5, 18,41, 74 and 126 yr for the Lugg catchment, Herefordshire. These used an erodible sandy loam soil that represented the dominant erodible soil type of the Lugg catchment, and a 17o slope representing the 80th Percentile slope for these erodible soils within the Lugg catchment. There were no significant differences in sediment removal efficiency between the treatments, irrespective of fill media (Woodchip or PAS 100 Compost), PSM (ferrihydrite ochre, goethite ochre, proprietary product), or rainfall event. Sediment removal efficiencies ranged from 66 – 97%. Treatments consistently removed up to 88% and 82% of eroded clay and silt sized particles, which is significant for the effective removal of sediment-bound phosphate. Ferrihydrite was the most effective PSM for orthophosphate removal with removal efficiencies of up to 34%. The 3 year trial indicated that more research is required to establish the wider validity of FS as a mitigation measure. This needs to encompass extensive field trials, incorporating their efficacy in other cropping situations with different soil types, slopes and climate conditions (e.g. annual rainfall). The research showed that PSM-amended FS are efficient at concurrently removing sediment, sediment-bound phosphate, and orthophosphate from runoff in laboratory studies, and are efficient under a range of laboratory based rainfall events. However this needs to be verified in field conditions to ensure that they remain a viable mitigation option for the future. Furthermore, research needs to be undertaken into the longevity of the materials for sediment and orthophosphate control in field conditions.
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
Natural vegetation cover changes in north-east Libya.
(Cranfield University, 2019-07) Almesmari, Nagat M. G.; Hallett, Stephen; Simmons, Robert W.
The vegetation cover in Al Jabal Al Akhdar has been subjected to human and natural pressures that have contributed to the deterioration and shrinking of the vegetated area. Therefore, the principle goal of this dissertation was to establish and evaluate the changes in the natural vegetation of the Al Jabal Al Akhdar region in the period following the 2011 Libyan uprising. The thesis is comprised of three main objectives; the first is to provide a quantitative assessment of changes in natural vegetation cover over a period from 2004-2016, and identify the consequent impact of human activity; the second is to investigate the impact of climate on the natural vegetation cover; and the third objective is to evaluate the ability of machine learning techniques to predict the natural vegetation cover types. GIS and remote sensing techniques and Landsat imagery, population MODIS NDVI and climate satellite-based data have been used to achieve these objectives, along with the ancillary data, across 53 sites in the study area. Six classified Landsat image scenes have been used for undertaking a post- classification comparison approach to detect the changes and the types of changes, by the use of image processing, GIS software and spreadsheet, and programme scripts used to detect LULC changes and determine human activities impact. The correlaction between the ANDVI and climate factors for each lanform, and the trends of climate factors and ANDVI for each sites in each landform have been undertaken using statistical analysis package and spreadsheet. Lastly the machine learning ‘J48’ algorithm, within the WEKA tool, was applied on ANDVI, climate data, and spatial characteristics for 53 sites and analysed statistically to test its ability to predict the natural vegetation type. The main research findings have confirmed that from 2004-2016, natural forest and rangelands decreased by 71,543 ha or 7.10% of the total area as a result of urbanisation and agricultural expansion. Human activities have had more impact than climate impact on LULC changes. The machine learning classifier decision tree ‘J48’ algorithm was also found to have the ability to classify and predict the natural vegetation cover type. Finally, an evaluation was undertaken of the current distribution of natural vegetation cover, and a forecast of future changes, utilising high-resolution imagery is recommended. A conclusion considers how developing action plans using tools such as those described to manage and protect the natural vegetation cover are highly recommended.
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.
Open Access
Optimising soil disturbance and mulch attenuation for erosion and runoff control in asparagus crops
(Cranfield University, 2014-12) Niziolomski, Joanna; Simmons, Robert W.; Rickson, R. Jane
Exposure of bare soil for long periods and onsite compaction create soil and water problems in asparagus production. This project aims to develop a cost effective and practical runoff and soil erosion management system. Two field trials (Phase 1 running from April - July 2012 and Phase 2 running from May - November 2013) tested different combinations of shallow soil disturbance (SSD) and mulch (straw and compost) application for soil erosion control. Cranfield University’s soil bin was used to test the effect of different tine configurations on soil disturbance. The results of this research corroborated observations that asparagus production can result in levels of unsustainable soil loss that will contribute to the degradation of the existing soil resource. The field trials demonstrated that a straw mulch applied at 6 t ha- 1 significantly improved key performance indicators (KPIs, i.e. runoff initiation, volume and rate; total soil loss; sediment concentration; total oxides of nitrogen; orthophosphate-P; and sediment-bound P) as compared with the Non-SSD Control. In general, SSD (irrespective of tine configuration) was ineffective at improving key performance indicators as compared with the Non-SSD Control. In the soil bin work, different tine configurations generated varying degrees and extent of SSD, with the modified para-plough giving the greatest soil disturbance for the least draught force. However, the differences in SSD observed in the soil bin had no effect on the KPI’s tested in the Phase 2 field trial. The effective treatments observed in the field trials only yielded cost savings to the farmer/grower when a high level of soil loss occurred. This research highlights the need to develop erosion control measures in asparagus fields, with wider implications to other row crops. However caution is needed, given the observed variation in effectiveness and reliability of in-field mitigation measures, especially during ‘extreme’ rainfall events.