5. The main direct effects of drought on the farming sector are summarised in Figure 1. The most immediate consequence of drought is a fall in crop production, due to inadequate and poorly distributed rainfall. Farmers are faced with harvests that are too small to both feed their families and fulfill their other commitments. Livestock sales act as a buffer in times of hardship, farmers disinvesting in these assets to buy food. The first animals to be sold are usually those which make the least contribution to farm production, such as sheep and goats. However, as the period of drought-induced food deficit lengthens, farmers will have to start selling transport and draft animals, such as oxen and donkeys, as well as breeding stock, which constitute the basis of the household's wealth. In the Ethiopian highlands, stock are usually disposed of in the following order: sheep and goats, then younger cattle, with horses, donkeys and work oxen being sold as a last resort (Wood, 1976), since the latter are essential for land preparation.
6. Where crops have been badly affected by drought, pasture production is also likely to be reduced although output from natural pastures tends to be less vulnerable to drought than crop production. Low rainfall causes poor pasture growth and may also lead to a decline in fodder supplies from crop residues. Insufficient levels of fodder around the village lead to weight less and increased deaths among stock, especially where immigrant herds put further pressure on limited local pastures. While the response of most pastoral groups to fodder shortage is to move themselves and their herds elsewhere, this is not an option so easily followed by livestock-owning farmers. Typically, farmers own fewer animals and have less familiarity with regular transhumance than pastoralists, both of which act as constraints on migration. In addition, few farm households will have sufficient labour to both take their animals to other grazing areas and continue with necessary farming operations. Thus, sedentary herds can be particularly badly hit in times of drought. A recent survey of deaths among draft animals in the Niono area of north-west Mali found losses of between 50 and 70% over the period 1983-84 (FAO, 1984). These high losses were caused by pasture shortages exacerbated by herds from further north on their way to southern pastures, by the sedentary character of livestock holdings amongst farmers in this area and by the normal dependence of horses (and to some extent donkeys) on a daily grain ration to supplement natural grazing, a supplement which is no longer given because of poor harvests.
7. The overall effect of a fall in fodder and crop production is to reduce the draft capacity of the farming sector, leading to lower crop output in the subsequent farming season. Loss of livestock around the farming settlement also reduces the household's access to dung, a product of considerable importance both as a fuel where firewood is scarce and as a means to retain fertility on regularly cropped soils.
8. The role and importance of dung varies between farming systems according to a number of factors. Shortage of fuelwood makes dung a highly valued commodity in many parts of the Ethiopian highlands where other sources of fuel are scarce. Dung is estimated to be the second most important product gained from livestock after draft power in such areas, providing up to 80% of the household's fuel needs in many areas (Gryseels and Anderson, 1983). In addition, sales of dung cakes make a contribution to cash incomes. In many parts of West Africa, dung is a major element in the exchanges established between pastoral and farming communities. Transhumant herders agree to station their animals overnight on farmers' plots in return for grain, cash or water. This manuring of fields produces a considerable increase in crop yields and is of especial value in marginal farming zones in the Sahel as it enables a larger area to be sown with rapid maturing crop varieties. Drought affects the availability of dung to the farm household in two ways. First, the number of animals owned by the farming population falls with death and sales among stock. Second, drought both reduces the size and changes the pattern of movement among pastoral herds. In the Sahelian context, drought conditions will force many herd-owners further South than normal in their search for fodder and water. Farmers in the southern Sahel, who regularly rely on visiting herds for supplies of dung will find their access to this commodity greatly reduced in a drought year. But contrast, yet further south, dung supplies will increase for those farming communities in savannah areas which are host to immigrant pastoral herds in a drought year.
9. Although they could not be considered as a loss to the national economy, to the individual farmer drought-induced distress sales of work oxen are as much of a loss as are animal deaths. In addition, since distress sales are associated with reduced prices offered, farmers also incur a substantial financial loss compared to sales under more normal circumstances. The distribution of work oxen losses between deaths and distress sales will vary according to the circumstances in which drought has taken place and the constraints faced by different producers. A report by the Relief and Rehabilitation Commission of Ethiopia for the province of Wollo in 1974 presents data showing almost all losses to have been due to deaths rather than sales: 71% dead from starvation, as opposed to 19% sold, leaving 2% disposed of by other means and 8% remaining (Wolde Mariam, 1984). By contrast, Wood's survey of farmers in the northern highlands of Ethiopia in 1974 found that most livestock losses were the result of distress sales in order to raise cash rather than deaths due to inadequate fodder (Wood, 1976). As will be discussed later, the circumstances in which oxen are lost have differing implications for the action that governments or agencies should take in moderating the effects of drought.
10. One means by which farm households try to make ends meet in times of crop failure is to release labour to earn income elsewhere; at the same time, this reduces the burden on household food reserves. The net effect on farm productivity depends on whether this migration continues into the next farming season, thereby reducing the household's labour supply. This will be the case where shortage of food is so acute that the household must depend on the earnings of some of its members to feed the rest of the family until the next harvest.
11. Changes in the distribution of wealth usually accompany drought. The experience of farm households will differ according to their ownership of assets, their access to incomes from other sources and the extent to which these assets and incomes are less affected by drought than are harvests. The most vulnerable amongst those hit by drought will be those with few assets to sell, those who most need to purchase grain due to an absence of their own household reserves and those who cannot pin access to food through other means, such as borrowing, coercion or theft. The richest members of the community may even be in a position to benefit during drought, as they can acquire land and other assets at low prices from distress sales by poorer neighbours. The differential impact of drought on the incomes and assets of rich and poor is formalised by Sen in his essay on "Poverty and Famines" (1981). He showed an individual's entitlement to food depends not only on direct output of crops, etc. but also on his access to food through the market, by the sale of labour or other commodities and through non-market mechanisms, such as redistributive systems within society. In times of drought, not only is there a direct shortfall of food production but also relative price movements of grain versus other commodities may drastically reduce the purchasing power of groups. Ibis is seen in the case of pastoralists who face rising grain prices but failing livestock prices as drought intensifies. Pastoralists face a major decision problem related to the timing of sales which minimize unfavourable grain/livestock ratios. Many farmers may be in a similar situation, needing to sell livestock, labour or land in markets where an excess supply of these commodities has reduced their value.