The demand for both food and energy will increase with at least 70% in the coming 40 years due to the forecasted growth in global population and average income (FAO, 2009). Although there is consensus in the literature that high crop productivity is a prerequisite to meet global future needs, there is also growing awareness that resources are limited (fossil energy, phosphorus, fresh water) and that they should be used more efficiently (Lobell et al., 2009; Foley et al., 2011; Tilman et al., 2011).
To identify the scope for sustainable improvement of the use of nitrogen (N), phosphor (P) and water in crop production spatially explicit information and knowledge needs to be integrated for benchmarking current N, P and water use and use efficiency against theoretical limits. This benchmarking can be used to improve current input use of N, P and water and can contribute to more sustainable crop production through higher use efficiencies.
A new, generic and robust methodology, based on the smart integration of existing sub-models will be developed and applied to calculate crop and location specific minimum N, P and water use as function of user-defined yield targets and site conditions, while maintaining or improving soil fertility. The minimum input use correlates with local highest input use efficiency and minimum losses of N, P and water inputs to the environment for the given yield target. The calculated results will refer to situations where the soil N fertility is maintained in the long term by balancing inputs and outputs of soil N. In the methodology the dynamics of soil P accumulation will also be calculated for situations where P input exceeds P output, until an equilibrium in soil P is reached.
The methodology will be tested using experimental data on yields, fertiliser inputs and calculated water use of wheat and maize grown in contrasting environments (sub Saharan Africa and Europe). The methodology will enable interactive use (e.g. by supplying yield targets and local characteristics) and will be linked to data from the benchmarking atlas. Spatial data will be used to develop methods to upscale local field data to regions and countries.
The project comprises four main objectives:
- to develop a generic and robust methodology to calculate the theoretical limits for N, P and water use and use efficiencies of crop production as function of yield target and site conditions;
- to test this methodology with experimental data of two crops from contrasting environments;
- to link this methodology to the benchmarking atlas of the IPOP programme and develop a method for up scaling of local results;
- to assess the effects of weather variability on calculated N, P and water use efficiencies.