The ISFM definition proposes that application of fertiliser to improved germplasm on responsive soils will boost crop yield and improve the agronomic efficiency relative to current farmer practice, characterised by traditional varieties receiving too little and insufficiently managed nutrient inputs (Step A – blue line, Figure 2). Major requirements for achieving production gains on ‘responsive fields’ within Step A include (i) the use of disease-resistant and improved germplasm, (ii) the use of the correct fertiliser sources, and rates, (iii) appropriate fertiliser use in terms of placement and timing, and (iv) crop and water management practices.

  • Combined application of organic and mineral inputs. Organic inputs contain nutrients that are released at a rate determined in part by their chemical characteristics or organic resource quality. However, organic inputs applied at low rates commonly used by smallholder farmers in Africa seldom release sufficient nutrients for optimum crop yield. Combining organic and mineral inputs has been advocated as a sound management principle for smallholder farming in the tropics because neither of the two inputs is usually available in sufficient quantities and because both inputs are needed in the long run to sustain soil fertility and crop production.