The national net production index number of the Food and Agriculture Organization (FAO) is chosen to illustrate changes over the past four decades in the total commodity production from farming systems. The indices are calculated by the Laspeyres formula (FAO, 2003), which aggregates different commodities (production minus feed minus seed) valued at constant 1989-1991 prices. This means that the production index number represents a relative value of net production volumes. For the purpose of the current study, the production index number is indexed for the base period 1960 (100). Production index data are compared with labour input, agricultural land use and fertilizer use, where possible separately for crop and livestock production. The data of indicator countries are aggregated to farming systems data using the same calculation method as in Chapter 3.1 Changes in production index number are compared with changes in the relative use of agriculture area, labour input and fertilizer consumption in Figures 4.1, 4.2 and 4.3. The first three variables are expressed as indices and set to 100 in 1960. Fertilizer consumption could not be indexed. Small absolute changes in the generally low fertilizer use - often a few kilograms per hectare only - result in huge relative changes. Therefore the absolute use of fertilizers is presented in the graphs on a second Y-axis. This presentation also reveals the large variation in fertilizer consumption among countries. Although the fertilizer data refer to total use over all agricultural activities, fertilizers are probably mainly used for crop production and not for fertilizing pastures. Therefore fertilizer data are only presented in the figures of crop production (Figure 4.2).
The analyses reveal large differences among farming systems. In all four systems, land productivity rose consistently over the 40-year period, when crop and livestock production were both considered (Figure 4.1). It rose about three-fold in the irrigated system, which was far in excess of the other three systems. On the other hand, agricultural labour productivity only rose in the irrigated system, being virtually stagnant in the other three systems.
In all four systems, crop land use rose substantially, reflecting the fact that (as shown in Chapter 2) land expansion explained about 60 percent of the increase in cereal production in all of Africa. Only 40 percent was due to increased cropland productivity. In these four systems it seems that the contribution of cropland productivity gains to total crop production may have been greater than in other systems in Africa, especially after 1985 (Figure 4.2). Again the irrigated system recorded by far the highest land productivity growth. It was two to three times greater than in the other three systems. It appears that crop fertilizer use per hectare rose in all four systems during the period, and its rate of growth was greater than the rate of growth in the area of crop land, especially in the irrigated system.
Another factor that is not captured in Figure 4.2 is the increase in the intensity of land use over the period. Especially in irrigated and higher rainfall systems, there has been a trend towards growing two and sometimes three crops a year from the same land. The measure of land area used here does not reflect these changes. Hence the apparent land productivity increases are in fact overestimates of the increases in productivity per unit of total or gross cropped land. They in fact only represent the productivity per unit of net cropped land.
In the maize mixed system, fertilizer use was a mere 3 kilograms per hectare in 2000, declining from 3.5 kilograms per hectare in the 1980s and 1990s. Average rates reach are the highest at 12 and 8 kilograms per hectare in Malawi and Zimbabwe, respectively. These may be atypical of the maize mixed system in Africa because of the highly subsidized starter pack programs in Malawi and the importance of the large commercial farm activities in Zimbabwe. Application rates are insignificant in the other countries practicing this farming system. In the irrigated system, the crop productivity increase is associated with a similar increase in fertilizer consumption, which reached absolute rates of almost 400 kilogram per hectare. This suggests that no improvement in fertilizer use efficiency was achieved over the past four decades. In the tree crop and cereal/root crop mixed systems, less than 1 kilogram per hectare of fertilizers are applied. Hence in all the rainfed mixed priority systems, there would appear to be considerable scope for increased use of fertilizers.
There has been a steady and dramatic rise in livestock productivity per hectare in all four priority farming systems (Figure 4.3). The area of permanent pastures in countries where these systems predominate has virtually remained constant over the last four decades. The question arises as to what other inputs have contributed to the substantial increase in livestock production. Improved pastures have not increased significantly in Africa over this period. It would appear that increased use of feedgrains, improved animal disease controls and some genetic improvement may have contributed. However, this remains a topic for further research.
The analysis at the priority farming systems scale shows that area expansion has only explained part of the increase in crop production. It is likely that increased fertilizer and land use intensity and increased labour inputs has accounted for a significant part of the crop production increase. In this process labour productivity has probably not increased at all. In contrast, agricultural labour productivity increased six-fold in Western Europe and four-fold in Northern America over the past four decades. Yields in Europe were comparable to current yield levels in Africa in the early 20th century. Labour productivity over the past century has increased two-hundred-fold in Europe.
