23.08.2013

This is why the definition focuses on maximising their use efficiency. Agronomic efficiency (AE) is defined as the extra produce generated (in kg) per unit of nutrients applied (in kg).

  • Fertiliser and improved germplasm. In terms of response to management, two general classes of soils are distinguished: (i) soils that show acceptable responses to fertiliser (Step A – blue line, Figure 2) and (ii) soils that show minimal or no response to fertiliser due to other constraints besides the nutrients contained in the fertiliser (Step B – green line, Figure 2). We have classified above soils as ‘responsive soils’ and ‘poor, less-responsive soils’ respectively. In some cases, where land is newly opened, or where fields are close to homesteads and receive large amounts of organic inputs each year, a third category of soil exists where crops respond little to fertiliser as the soils are fertile. These soils need only maintenance fertilisation and are termed ‘fertile, less responsive soils’.