Suitable areas in Africa
In 2009, the Food and Agriculture Organization (FAO) estimated that 70% more food needs to be produced by 2050 to meet the growing global demand, driven by a larger and more affluent population.
On top of that, the increased demand for biomass required for a transition towards a fossil-free economy further adds to the urgency to increase agricultural production. At the same time, major agricultural resources, such as productive agricultural land, water, and nutrients are limited at local levels. Therefore, increasing agricultural production should be accompanied with improvements in resource use efficiencies. However, detailed insight is lacking as to where these increases in production and improvements can best be realised due to large spatial and temporal variation, for example, in biophysical resources.
Analogous with yield gaps, illustrating the potential to increase crop yields, calculated nitrogen (N) use efficiencies can be compared with actual N use efficiencies to reveal options for improvements.
We used a spatially explicit methodology to illustrate variations due to local conditions (viz. hotspots of high or low nitrogen use efficiency) and to estimate possible grain productions and associated nitrogen fertilizer needs at local, provincial and national levels.
Methodology
The models used are LINPAC (LINtul model for Perennial and Annual Crops) and NARC (Nutrient Application Requirement Calculator).
Results
As a result of differences in local soil and weather conditions simulated average rain fed maize yields in 1999 – 2010 vary from less than 1 to more than 4 ton grain dry matter per ha with a fertilizer application of 100 kg N ha-1.