Concerns about limited availability and pollution of freshwater require that water and fertilizer use efficiencies increase, while not exceeding critical loads of nutrients. Quantitative analyses of achieved and desired efficiencies are urgently required. Such analyses need to be conducted at relevant spatial and temporal scales. Agricultural yield and resource use efficiency are typically assessed at the field level, while management and resource use decisions are typically made at the farm level, taking account of e.g., crop rotations, competing off-farm farming activities and differences in biophysical and socio-economic conditions. Similarly, water and nutrient dynamics in a given area are strongly driven by hydrological processes at the catchment level. There is a time lag between the application of nutrients, leaching to groundwater or run-off to surface water. The results of interventions may thus be visible at different time scales for different spatial scales. Thus, processes at field and farm level need to be integrated with processes acting at the water-system scale.
Results from the Global Yield Gap and Water Productivity Atlas (GYGA; www.yieldgap.org) allow for the identification of priority regions for sustainable intensification. For different regions emphasis may be on improving the sustainability or on intensification, depending on current farm management and on potentials. Related interventions will affect water fluxes (e.g. evapotranspiration, runoff, recharge, return flows) and nutrient fluxes (e.g. plant uptake, nutrient runoff, effluents) in water systems. In order to achieve sustainable intensification of crop production, the effects of interventions need to be understood at both field- and system levels. The analysis aims to yield indicators for water stress (quantity and quality) at different relevant levels within socio-ecological systems. To develop a water stress (quantity and quality) assessment approach, models are used to simulate hydrological processes that affect water- and nutrient fluxes (focus on Phosphorus) across scales. To achieve this the proposed research will combine and build on existing approaches
The proposed approach serves to translate the information from GYGA into information that supports decision-making by chain actors. Results of the assessments will support the development of sustainability indicators and the implementation of Corporate Social Responsibility (CSR) strategies.