World Bank Document

PHN Technical Kote 85-19a Public Disclosure Authorized POPULATION GROWTH AND AGRICULTURAL PRODUCTIVITY IN SUB-SAHARAN AFRICA by Teresa J. Ho Public Disclosure Authorized November 1985 Population, Health and Nutrition Department World Bank Public Disclosure Authorized The World Bank does not accept responsibility for the views expressed herein which are those of the author(s) and should not be attributed to the World Bank or to its affiliated organizations. Tne findings, interpretations, and conclusions are the results of research supported by the Bank; they do not necessarily represent official policy of the 3ank. The designations employed, the presentation of material, and any maps used in this document are solely for the convenience of the reader and do not imply the expression of any opinion whatsover on the part of the World Bank or its affiliates concerning the legal status of any country, territory, city area, or of its authorities, or concerning the Public Disclosure Authorized delimitations of its boundaries, or national afLiliation. PHN Technical Note 85-19a POPULATION GROWTH AND AGRICULTURAL PRODUCTIVITY IN SUB-SAHARAN AFRICA A B S T R A C T This paper considers the consequences of rapid population growth on labor productivity in agriculture in sub-Saharan Africa. Observers have often pointed to the presence of large untapped land resources in the region to deny the presence of a population problem; in addition, a recent Food and Agriculture Organization study on potential population supporting capacities estimated that sub-Saharan Africa can support a population more than double its present size even with the most rudimentary of inputs and technology. This paper argues that despite this large potential, population growth is contributing to declines in agricultural ,Productivity even at present. Two explanations for this early onset of declining productivity are offered. First, the distribution of population in sub-Saharan Africa is not congruent with the distribution of natural resources; hence there are large differences in population-natural resource balances across the region with a few countries already at a critical stage of population pressure. Second, when agriculture is unable to progress to higher levels of technology during a period of growing demand for agricultural output, the onset of diminishing returns to labor may occur earlier than otherwise as a result of declining soil productivity. The paper discusses indica- tions that much of sub-Saharan Africa may already have reached this point. Prepared by: Teresa J. Ho Population, Health and Nutrition Department November 1985 Population Growth and Agricultural Productivity in Sub-Saharan Africa 1. Is Population Growth a Factor in Sub-Saharan African Agriculture? The relationship between population growth and agricultural growth is well recognized. In countries where populatiion is growing at high rates, there is pressure on agriculture to expand more quickly in order to feed the growing population or to generate the income from agriculture that would feed the growing population. This is especially true for many countries of sub-Saharan Africa (SSA) where population is growing at unprecedented rates and where large proportions of the population are dependent on agriculture for their income. Unfortunately, agricultural growth in SSA has been excep- tionally slow, causing increasing numbers of Africans to remain in poverty and in fact suffer deteriorating living conditions. There is another link between population growth and agriculture that extends beyond this pressure to produce more food for a growing dependent population. Population growth can have a more direct influence on agriculture through its effect on the productivity of labor in agriculture, the result either of economies of scale, at the earlier stages of population growth, or diminishing marginal returns to labor at the later stages as the population's s'.ze starts to exert undue pressure on fixed land resources. Because of ':he low population densities in SSA, the common belief is that only economies of scale are operating there at present and that diseconomies are not antici- pated until much later. This seems especially true because only a very small proportion of potentially arable land is under cultivation in the region and there is at present little pressure in agriculture to move to marginally productive lands except in extreme cases like Rwanda, Burundi, and the Kenyan highlands. This paper aims to explore the hypothesis that population growth is caLsing declines in agricultural productivity in SSA at present, despite the presence of large untapped land resources in the region. Two explanations are proposed for this early onset of declining productivity. First, the distribution of population in SSA is not congruent with the distribution of natural resources; hence, there are large differences in population- resource balance across the region with a few countries already at critical stages. Second, in a situation where agriculture is unable to progress to higher levels of technology, as is true in SSA, the onset of diminishing returns may occur earlier than otherwise: much of SSA agriculture may already have reached this point. The paper begins with a (i-scussion of SSA's poor performance in agriculture over the last decade and contrasts that with the region's vast potential population supporting capacity. It shows wide inter-country variations in carrying capacity as well as in the extent to which different countries have approached or exceeded capacity. It then examines the relationship between a country's population-resource balance and its agricultural performance. The discussion highlights the fact that population size may already be a problem for many SSA countries as they approach the limits of their agricultural carrying capacities. -2- The effects of population growt on prospects for agricultural growth and technological change will then be discussed. The argument will center around the relationship between population growth, the length of fallow periods in the forest and bush fallow systems of SSA, and the effects of shortening fallows on soil fertility. The critical role played by technological change in this agricultural system will be emphasized and related to the unprecedented juxtaposition of early-stage agricultural transition with later-stage demographic transition. Finally, conditions under which population growth would generate, and those under which it would constrain, agricultural growth will be identified. The ultimate objective is to suggest ways in which agricultural sector development considerations can be integrated into population policy decisions and, conversely, to suggest ways in which population density and growth variables can be integrated into agricultural planning. 2. Population Growth, Carrying Capacity, and Akgricultural Growth in Sub-Saharan Africa During the twelve years from 1970 to 1982, agricultural production in SSA grew at an average of 1.5 percent per year, much lower than the average of 2.5 percent for all low income countries combined and lower than that for Bangladesh (2.3 percent) or India (1.8 percent). During the same period, SSA's population grew at 2.9 percent per year, almost twice as fast as agricultural production. As a consequence, per capita food production for 1980-82 was only 92 percent of the 1969-71 level, reflecting a deterioration in agricultural performance over the decade of the seventies. The low income countries in SSA fared especially badly, with food production per capita in 1980-82 only 87 percent of the 1969-71 level; even Bangladesh, the Lowest income non-African country, performed better with a corresponding per capita production index of 94 percent. (See Table 1 for comparative statistics.) How can such poor performance be explained? Much of the failure of SSA agriculture has been blamed on a public policv structure that fails to provide the right incentives for growth. Tn particular, tariff and exchange rate policies that discourage agricultural exports and encourage food imports have been cited (World Bank 1981). But beyond the effects of price and incentives policies, there could be factors at plav in SSA that would make growth in agricultulrf- difficult even Lf countries "got the prices right". This paper argues that one such factor could be the effect of population pre3sure on limited land resources, and hence on agricultural productivity. The figures in Table I show that SSA is different from other developing regions of the world in both population and agriculture sectors. Demographically, it has lower densLty and h:igher growth than all other regions: agriculturally, it is growing more slowly than other regions. As will be discussed later in this paper, its agriculture is presently at a level of technology far more primitive than in most other regions. All these suggest that SSA may not necessarily follow a development path -3- similar to that experienced by other regions that are now further along in the agriculturai transition. SSA's grim performance over the last decade stands in stark contrast with the picture of a region with large tracts of unused land and promise of much potential. Recent estimates by the FAO (Higgins et al 1982) of agricultural potential in different regions of the world give the best estimates to date of the magnitude of that potential'. Estimates are made for three different levels of technology - low, intermediate and high - and are computed on the basis of expected production levels given local soil and climatic conditions. These levels of technology are defined as shown in Table 2. Figure 1 shows the FAO's estimate of current technological levels in Africa and other parts of the world based on available information on yield levels and on extent of fertilizer use. With either measure, Africa is shown to be at or almost at the low level as defined by the FAO. Et is much behind other developing regions which are roughly one-third to one-half the distance to the intermediate level. In contrast, Western Europe is at the high input level.

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