Browsing by Author "Higgins, Suzanne"
Now showing 1 - 8 of 8
Results Per Page
ItemA machine learning approach to predicting plant available phosphorus that accounts for soil heterogeneity and regional variability(2023-09-20) Hall, Rebecca L.; de Santana, Felipe Bachion; Grunsky, Eric C.; Browne, Margaret A.; Lowe, Victoria; Fitzsimons, Mairéad; Higgins, Suzanne; Gallagher, Vincent; Daly, Karen; Environmental ProtectionPurpose Mehlich-3 extractable P, Al, Ca, and Fe combined with pH can be used to help explain soil chemical processes which regulate P retention, such as the role of Al, Ca, Fe, and pH levels in P fixation and buffering capacity. However, Mehlich-3 is not always the standard test used in agriculture. The objective of this study is to assess the most reliable conversion of Mehlich-3 Al, Ca, Fe, and P and pH into a commonly used soil P test, Morgan’s P, and specifically to predict values into decision support for fertiliser recommendations. Methods A geochemical database of 5631 mineral soil samples which covered the northern area of Ireland was used to model soil test P and P indices using Mehlich-3 data. Results A random forest machine learning algorithm produced an R2 of 0.96 and accurately predicted soil P index from external validation in 90% of samples (with an error range of ± 1 mg L−1). The model accuracy was reduced when predicted Morgan’s P concentration was outside of the sampled area. Conclusions It is recommended that random forest is used to produce Mehlich-3 conversions, especially when data covers large spatial scales with large heterogeneity in soil types and regional variations. To implement conversion models into P testing regimes, it is recommended that representative soil types/geochemical attributes are present in the dataset. Furthermore, completion of a national scale geochemical survey is needed. This will enable accurate predictions of Morgan’s P concentration for a wider range of soils and geographical scale. ItemEffect of increasing the time between slurry application and first rainfall event on phosphorus concentrations in runoff(Wiley, 2021-07-12) O'Rourke, Sharon M.; Foy, Robert H.; Watson, Catherine J.; Gordon, Alan Wesley; Higgins, Suzanne; Vadas, Peter A.Minimizing slurry phosphorus (P) losses in runoff requires careful management in the context of both soil P surpluses and changing patterns in rainfall. Increasing the time interval between slurry application and the first rainstorm event is known to reduce P loss in runoff although the risk period for elevated P concentrations in runoff can extend for weeks. This study investigated the impact of increasing the time interval between slurry application and first rainstorm event on P concentrations in runoff. Simulated rainfall (40 mm h−1) was applied at 2, 4, 10, 18, 30 and 49 days after dairy slurry was surface-applied to a grassland sward in Ireland. Increasing time to runoff resulted in a decrease in dissolved reactive P concentrations from 5.0 to 1.0 mg P L−1 and a P signal in runoff for 18 days. Beyond 18 days, elevated P concentrations were observed in runoff collected from natural rainfall that preceded the day 49 rainstorm event. A published surface phosphorus and runoff model (SurPhos) was used to understand the slurry P dynamics controlling P interactions with runoff. Dissolved reactive P in runoff was predicted with accuracy by SurPhos, R2 = .89. The SurPhos model implied that slurry P mineralization occurred during the experimental period that resulted in a small spike in P concentrations beyond the defined risk period. This study shows that the experimental data have the potential to be extrapolated to different weather scenarios using SurPhos and could test when and where slurry P could be most safely spread. ItemGrassland Reseeding - Improving Grassland Productivity and Reducing Excess Soil-Surface Nutrient Accumulations(MDPI, 2022-02-10) Hayes, Emma; Higgins, Suzanne; Geris, Josie; Mullan, DonalLong-term phosphorus (P) accumulation in agricultural soils presents a challenge for water quality improvement. P is commonly elevated in soils managed for intensive livestock production due to the repeated over-application of slurry and fertilizers. High legacy nutrient accumulations can result in poor water quality via transport pathways such as surface runoff, subsurface drainage, and soil erosion. To achieve the EU Water Framework Directive (WFD) aims, improved management strategies are required for diffuse and point P sources. Reseeding is known to improve grassland productivity and enhance overall soil health. However, soil disturbance associated with reseeding could have positive and negative effects on several other soil functions that affect the nutrient balance (including improved microbial activity, but also increasing the potential for sediment and nutrient losses). This study investigated the role of reseeding in addressing nutrient surpluses in surface soils and identified potential trade-offs between production, environment, and soil health. At a study site in the Blackwater catchment in Northern Ireland, we collected high-resolution gridded soil samples pre- and post-reseeding for nutrient analyses and combined this with GIS-based interpolation. We found that decreases in sub-field scale nutrient content occurred following reseeding, but that this was spatially variable. This indicates that this strategy is effective in reducing soil surface P accumulations. However, more research is needed to determine whether this P becomes available for grass uptake during re-growth or whether it increases the pool of mobile P, which can be lost in surface runoff, subsurface drainage, and soil erosion ItemGrassland Reseeding: Impact on Soil Surface Nutrient Accumulation and Using LiDAR-Based Image Differencing to Infer Implications for Water Quality(MDPI, 2022-11-04) Hayes, Emma; Higgins, Suzanne; Geris, Josie; Mullan, DonalLong-term phosphorus (P) accumulation in agricultural soils presents a challenge for water quality improvement. P is commonly elevated in soils managed for intensive livestock production due to repeated overapplication of slurry and fertilisers. High legacy nutrient accumulations result in poor water quality via transport pathways such as surface runoff, subsurface drainage, and soil erosion. To achieve environmental water quality targets, improved management strategies are required for targeting and reducing excess agricultural P sources. Reseeding of old swards is known to improve grassland productivity and enhance overall soil health. However, soil disturbance associated with reseeding could have positive and negative impacts on other soil functions that affect the nutrient balance (including improved microbial activity, but also increasing the potential for sediment and nutrient losses). This study investigates the impact of reseeding and inversion tillage in addressing soil surface nutrient surpluses and identifies potential trade-offs between production, environment (through soil erosion and associated sediment and nutrient losses), and soil health. At a study site in the Blackwater catchment in Northern Ireland, we collected highresolution (35 m) gridded soil samples pre- and post-reseeding for nutrient analyses and combined this with GIS-based interpolation. We found that decreases in sub-field scale surface nutrient content (0–7.5 cm depth) occurred following tillage and reseeding, but that this was spatially variable. In addition, the magnitude of changes in nutrient content was variable between P and other sampled nutrients. LiDAR-based image differencing indicated variability in the magnitude of soil erosion and sediment loss also at sub-field scale. Information on the identified deposition and erosion zones (from LiDAR analysis) was combined with mass wasting data to determine accumulation rates and losses of nutrients in-field and confirmed some of the identified patterns in soil surface nutrient content changes post-reseeding. We conclude that while inversion tillage and reseeding are essential agricultural practices, environmental trade-offs exist through potential nutrient and sediment losses. LiDAR-based image differencing was found to be a useful tool in helping to quantify these risks. Quantifying sediment and nutrient losses as a result of inversion tillage and reseeding induced soil erosion aids in understanding potential trends in water quality statuses. ItemHigh-resolution assessment of riverbank erosion and stabilization techniques with associated water quality implications(Taylor & Francis, 2023-05-26) Hayes, E.; Higgins, Suzanne; Mullan, D.; Geris, J.; Environmental ProtectionAgriculture is a key contributor to poor water quality, but the sources of sediment and nutrient losses from agricultural catchments – including from riverbank erosion – are highly variable. Riverbank erosion is particularly difficult to quantify and control. Here, we developed a quick assessment approach to quantify riverbank erosion rates and associated sediment and nutrient loading rates into waterways using airborne LiDAR combined with field-collected data. We applied this approach and explored its relationships to water quality at four sites within the Blackwater catchment in Northern Ireland for two analysis periods. GIS LiDAR image differencing revealed that volume changes in riverbank elevation equated to average erosion rates which indicated spatial and temporal variability in erosion rates. Combining the erosion rates with in-situ riverbank bulk density and total extractable phosphorus content provided sediment and phosphorus loading rates. The relative differences between estimated erosion at the different sites corresponded well with in-stream suspended sediment variations, but patterns for total phosphorus concentrations were more complex. We conclude that the use of LiDAR combined with field data is an innovative means for riverbank erosion quantification. Furthermore, by using LiDAR-to-LiDAR analyses, the reductions in erosion, sediment, and phosphorus loading rates following riverbank stabilization techniques can be determined. ItemThe Role of Proximal Sensors to Improve Land Management, Meet Environmental Targets and Increase Nutrient Use Efficiency on Farms(Crimson Publishers, 2021-10-08) Higgins, Suzanne; McConnell, DeborahIncreasing nutrient use efficiency on farms; improving land management; changing land use to capture more carbon, along with boosting renewable energy and the wider bio economy are practices that have been identified as key mechanisms by which the ambitious goal of achieving carbon net zero by 2050 can be achieved [1,2]. In order to increase nutrient use efficiency on farms, it requires knowledge and data collection to manage inputs, outputs, emissions and productivity. Soil and crop sensors can play an important role in improving the precision of agricultural practices while minimising harmful emissions to the environment. Rapid advances in technology mean that today there are many soil and crop sensors which provide a fast, powerful, non-destructive means of measuring a large number of chemical and physical properties. However, disentangling the data provided by soil and crop sensors can often be a challenge, particularly as some sensors and proximal sensor systems can be good proxies for more than one soil property. While it is possible to create very accurate and detailed soil maps using proximal sensors, there is nearly always a requirement to calibrate with local samples, as multiple factors can affect sensor measurements . Good processing and calibration are key, and the best results will be achieved when there is a wide variation of in-field properties . This mini review identifies two important case examples where proximal sensors can improve land management and farm nutrient use efficiency, which are both important concepts towards carbon net zero. ItemStocktake study of current fertilisation recommendations across Europe and discussion towards a more harmonised approach(Wiley, 2023-10-23) Higgins, Suzanne; Keesstra, Saskia D.; Kadziuliene, Zydre; Jordan-Meille, Lionel; Wall, David; Trinchera, Alessandra; Spiegel, Heide; Sandén, Taru; Baumgarten, Andreas; Jensen, Johannes L.; Hirte, Juliane; Liebisch, Frank; Klages, Susanne; Löw, Philipp; Kuka, Katrin; De Boever, Maarten; D'Haene, Karoline; Madenoglu, Sevinc; Özcan, Hesna; Vervuurt, Wieke; de Haan, Janjo; van Geel, Willem; Stenberg, Bo; Denoroy, Pascal; Mihelic, Rok; Astover, Alar; Mano, Raquel; Sempiterno, Cristina; Calouro, Fatima; Valboa, Giuseppe; Aronsson, Helena; Krogstad, Tore; Torma, Stanislav; Gabriel, Jose; Laszlo, Peter; Borchard, Nils; Adamczyk, Bartosz; Jacobs, Anna; Jurga, Beata; Smreczak, Bożena; Huyghebaert, Bruno; Abras, Morgan; Kasparinskis, Raimonds; Mason, Eloise; Chenu, Claire; Grassland and Plant ScienceThe European Commission has set targets for a reduction in nutrient losses by at least 50% and a reduction in fertiliser use by at least 20% by 2030 while ensuring no deterioration in soil fertility. Within the mandate of the European Joint Programme EJP Soil ‘Towards climate-smart sustainable management of agricultural soils’, the objective of this study was to assess current fertilisation practices across Europe and discuss the potential for harmonisation of fertilisation methodologies as a strategy to reduce nutrient loss and overall fertiliser use. A stocktake study of current methods of delivering fertilisation advice took place across 23 European countries. The stocktake was in the form of a questionnaire, comprising 46 questions. Information was gathered on a large range of factors, including soil analysis methods, along with soil, crop and climatic factors taken into consideration within fertilisation calculations. The questionnaire was completed by experts, who are involved in compiling fertilisation recommendations within their country. Substantial differences exist in the content, format and delivery of fertilisation guidelines across Europe. The barriers, constraints and potential benefits of a harmonised approach to fertilisation across Europe are discussed. The general consensus from all participating countries was that harmonisation of fertilisation guidelines should be increased, but it was unclear in what format this could be achieved. Shared learning in the delivery and format of fertilisation guidelines and mechanisms to adhere to environmental legislation were viewed as being beneficial. However, it would be very difficult, if not impossible, to harmonise all soil test data and fertilisation methodologies at EU level due to diverse soil types and agro-ecosystem influences. Nevertheless, increased future collaboration, especially between neighbouring countries within the same environmental zone, was seen as potentially very beneficial. This study is unique in providing current detail on fertilisation practices across European countries in a side-by-side comparison. The gathered data can provide a baseline for the development of scientifically based EU policy targets for nutrient loss and soil fertility evaluation. ItemWeighted risk assessment of critical source areas for soil phosphorus losses through surface runoff mechanisms(Elsevier, 2023-02-26) Hayes, Emma; Higgins, Suzanne; Geris, Josie; Nicholl, Gillian; Mullan, DonalIn intensive livestock areas, soils commonly contain elevated nutrients above the agronomic optimum which increases the risk of nutrient losses and contributing to poor ecological status waterbodies. Large within-field variability in soil nutrient content exists, and at-risk phosphorus (P) hotspots are rarely quantified due to sub-optimal soil sampling regimes. This study aims to address this issue by developing and evaluating an improved classification of P transfer risk at a sub-field scale through a weighted risk assessment model that combines gridded soil sampling data with modelled in-field surface runoff pathways. Within-field soil P variability was quantified at six field-scale sites in Northern Ireland using two different sampling techniques; traditional bulked field soil sampling (i.e. bulk analysis of W pattern sampling) and gridded sampling (at 35 m resolution) alongside interpolation. Results show that traditional bulked sampling failed to account for the sub-field scale spatial variability in soil P content. This may contribute to the poor chemical and ecological status of surface waters by frequently under-predicting soil nutrient content, and failing to identify potential contributing sources of soil P losses. In contrast, higher intensity gridded sampling and interpolation revealed wide in-field spatial variability in soil P content, facilitating the identification of contributing sources of P losses to poor water quality and aiding in the characterisation of risk for nutrient losses to waterways. Hydrological modelling of in-field runoff pathways indicated several P sources potentially contributing to runoff-based P losses. Our weighted risk assessment model was successful in identifying P hotspots and transfer potential to water courses, illustrating that a similar approach could be applied anywhere in the world where excess P poses a problem for water quality. Model validation took place using instream water quality sampling data, which showed that higher risk weighting model results correlated to poorer water quality conditions. This methodology could be a useful management tool to help countries meet their national water quality targets.