Benchmarking a decade of holistic agro-environmental studies within the Agricultural Catchments Programme

Abstract

Meeting sustainable food production challenges requires efficient ways to manage nutrients and mitigate the losses of nitrogen (N) and phosphorus (P) to water. Future nutrient management therefore requires a clearer understanding of the relative influence of soils, geology, farm practice, landscape and weather on the propensity for nutrients to be lost to water. Within the Agricultural Catchments Programme (ACP), environmental, agronomic and socioeconomic data have been gathered since 2009, using the same experimental methodology in five meso-scale river catchments, and one karst spring zone, covering a range of soils, landscapes and farming systems. The ACP has contributed to a better understanding of nutrient mobilisation and transfer pathways and highlighted the influence of the physical and chemical environment as well as agricultural and meteorological drivers on diffuse nutrient loss to ground and surface waters. The environmental quality standards were breached for N and/or P in some of the catchments, but for different reasons and not always clearly linked to the source pressures within the catchment. There are clearly no one-size-fits-all solutions for mitigation of nutrient losses to water. A better understanding of the underlying processes is required to identify critical source areas, to select mitigation strategies, when to implement them and to build realistic expectations of their impact. Sustainability in an agricultural setting is not confined to environmental issues, but also includes social, economic and innovative aspects. To maximise farmers’ uptake of environmental measures, the actions should encompass all these aspects of sustainability. Integrated knowledge transfer is key.

Phosphorus mobilization and delivery estimated from long-term high frequency water quality and discharge data

“…In a similar manner the introduced P delivery index was expressed as the ratio of a range of high P mass load and a range of low P mass loads, reflecting the possible range of P mass load and therefor integrated the catchments connection and retention factors into one number. The ranked order of the indices matched the conceptual understanding of the catchments (Mellander et al, 2018(Mellander et al, , 2022 and allowed a view of the catchments in terms of both dominating P fraction and transfer processes of P loss. These estimations also provided insights to how stable these processes were over time and if there were any inter-annual trends over the analyzed 10-year period.…”

“…Phosphorus mobilization in land runoff was described as detachment or solubilization of soil P, and P delivery as transport including connection and retention in the landscape (Withers and Haygarth, 2007). The model has been widely used as a conceptual framework for integrated catchments studies such as the Irish Agricultural Catchments Programme (Fealy et al, 2010;Mellander et al, 2022) and the DEFRA Demonstration Test Catchments in the UK (e.g., McGonigle et al, 2014). Such studies require a consideration of the complexity and influence of the landscape, land management, and the sequence of hydrological events on both the transport and the balance between particulate and dissolved P (Beven et al, 2005).…”