Figure 2-8. Wheat yields in ten NAE countries since 1950. Source: FAOSTAT, 2006; FAO Yearbooks 1950 and 1958.

2.    Increased availability of fertilizers and increased knowl­edge of how to use them;
3.    Development of new pesticides to control weeds, pests and diseases;
4.    Better understanding of the biotic and abiotic factors constraining yields, leading to optimizing agronomic practices (e.g., sowing dates, plant densities, fertilizer timing);
5.    Improvement in machinery design and range to assist optimization of crop production;
6.    Increased use of irrigation;
7.    Enhanced mechanisms for technology transfer, such as

development of national agricultural advisory systems; and
8.    The delivery of information by the private sector, e.g., on the use of their products. It is as important a source of information to farmers as the public sector extension services and related public sector support.

These advances are summarized in data from the long-term Rothamsted wheat experiment (Figure 2-9), which clearly shows the role played by a number of different inputs in delivering higher yields.
     While increasing productivity has been the main goal of