Intensify agriculture and protect the environment
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CTA. 1990. Intensify agriculture and protect the environment . Spore 29. CTA, Wageningen, The Netherlands.
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Over the centuries, farmers in the tropics have survived through good and bad years, in balance with the environment. But today population pressure on the land precludes practices that enable the environment to recover from extensive cropping...
Over the centuries, farmers in the tropics have survived through good and bad years, in balance with the environment. But today population pressure on the land precludes practices that enable the environment to recover from extensive cropping systems. As a result the forests are dying, the soil is disappearing, the desert is spreading. Destruction of natural resources - the soil and vegetation cover - due to constant clearance of new ground as a result of exponential population growth, destroys the balance of the environment and mortgages the means of future production. The productivity of the land, both in terms of yields and of the intensity of cultivation, must be improved. But this raises a fundamental question. What are the effects on the environment of intensive agricultural practices? Does agricultural intensification adversely affect the environment or is it a means of preserving it? What are the ultimate consequences of non-intensification? Should we intensify agriculture in the tropics or not? Can one compare the situation in the Third World to that in the industrialized countries where large quantities of agrochemicals are regularly used to produce uneconomic surpluses? Shifting cultivation has in the past, allowed the population of tropical countries to maintain a balance between their needs and the resources of the natural environment. In the course of its history, traditional agriculture has evolved gradually over centuries in a stable human environment. Such conditions no longer exist. As V Drachoussoff underlined, (1) 'one should not overestimate the ability of traditional agricultural systems to evolve. They can adapt to rapid but slight changes, or to those that are profound but slow. But change is now both rapid and profound (for example, in a population with a high growth rate and galloping urbanization), and these systems cannot support traditional cultural practices and conserve the soil, water and vegetation resources.' Is it better to build a dam or use chemical fertilizers, and deal with their drawbacks, rather than to pillage the last forests to gain a few thousand hectares of new land thus passing on the problem to the future generations? All these questions arise from a central preoccupation: how can developing populations avoid a terrible dilemma - to eat today at the risk of dying tomorrow or to make sacrifices and preserve the future? Is the development of food production compatible with the protection of the environment? Water, fertilizers, agrochemicals and mechanization are among the most important elements of modern agriculture. Most would agree that their intensive use has consequences for the quality of the environment. It is therefore important to review the impact of agricultural intensification in the tropics. Water: large or small-scale projects The example of the irrigated area of Gezira in the Sudan demonstrates the problems, even today, of large-scale irrigation schemes with major infrastructure requirements. The Gezira is the oldest and, at present, the largest irrigated area in Africa. During the last 12 years, yields of cotton have fluctuated around half a tonne per hectare and cereal yields have remained between one, and one-and-a-half tonnes per hectare. These can hardly be considered high yields in irrigated agriculture. However, since the rainfall of the region rarely reaches 400mm per year, and in some years an almost complete absence of rain precludes any harvest, it must be recognized that the Gezira scheme has provided, for almost half a century, subsistence for an environmentally underprivileged population. It is a fact that the large quantities of insecticides required to grow cotton cause pollution of soil and water. Thirty million dollars' worth of insecticides and six million dollars' worth of herbicides are used each year and their effects are felt by the population. It is clear that projects of this size can be damaging to the environment and this should be taken into consideration at the decision-making and planning stage. On the other hand, small-scale irrigation in the Sahel consists of many small developments fed by pumped ground-water. Successes have been achieved: in addition to providing water for the people these developments have permitted profitable agricultural activities, such as fruit growing and market gardens, tree nurseries and construction of watering points for livestock. In short, these schemes have been instrumental in rational development of the region. The effect of such developments on the environment is, at first sight, very positive. But the ill-considered use of ground water is not without consequence for future supplies of water. The increase in boreholes, has, unfortunately, resulted in chaotic management of the grazing areas with profound effects on the environment. Plant cover has been considerably impoverished, disappearing in many places over large areas around watering points and leading to wind erosion. Boreholes, combined with improved veterinary services have led to a rapid increase in livestock numbers. The herds are then forced to move south where the same practices which originally led to desertification in their countries of origin are repeated. It should be noted that, during the past ten years, remarkable successes have been obtained with a number of small-scale schemes entirely managed by the farmers themselves. (1) Spectacular results, with rice yields exceeding 10 tonnes per hectare in two growing seasons each year, have been recorded. These yields, which show the real potential of irrigation, should be compared with the yields from traditional cereal crops (millet and sorghum) which on average do not reach a half tonne per hectare. (2) Small-scale irrigation schemes in Madagascar have led to greatly increased productivity in traditional rice paddies, thanks to better water management in harmony with the social and ecological environment. Agrochemicals The industrialized countries use large quantities of chemical fertilizers and often optimum application rates have been exceeded. Furthermore, optimum rates of application from an economic standpoint do not correspond to those required to maintain the balance of the environment. In the African context, however, if lack of purchasing power has averted the drawbacks of overuse of fertilizers, it has also denied the continent the benefits of their rational use. In tropical countries, improved soil productivity resulting from fertilizer use has other advantages: increased biomass, better soil cover and, consequently, reduced risk of erosion and better preservation of soil organic matter derived from leaves and roots. Considering that agricultural losses due to pests amount to 30% of production, it is clear that pest control is essential, including the use of chemical products. But chemical pesticides have their drawbacks. They are expensive, dangerous to store and have a limited shelf-life. If used unwisely they are also hazardous to the environment. Experience has shown the dangers of accumulation of toxic residues both for humans and for the environment. Integrated pest control offers encouraging prospects for methods of crop protection that are less likely to alter the natural environment. These methods integrate chemical control with cultural practices, plant breeding and biological control. In view of me limits of intensive chemical control as well as those of biological control alone, integrated pest management rests on a thorough understanding of the interactions between pests, plants and beneficial organisms. Mechanization In Africa, whereas 80% of the population is involved in agriculture, food production levels remain inadequate. Therefore the profitability of labour must be improved. Agricultural mechanization has considerable prospects in this field so long as it is managed efficiently. Care must be taken not to leave fields badly cleared, insufficiently ploughed, and without protection against erosion or without restoration of organic matter. Mechanization should aim at maximizing the use of arable land, promoting the use of other production factors and it should lead to the improvement of crop performance. In regions with livestock, draught power is undoubtedly the type of mechanization most widely available and with the least financial risk since it requires a small investment and a minimum of family labour. Use of draught animals is, with penning of livestock for manure production, one of the best ways of integrating livestock and crop production. These two aspects of agriculture can be complementary rather than competitive. However, draught power has its limitations. It is difficult to implement in farming communities with no livestock tradition and it is limited by animal diseases. On its own it does not allow the mechanization of all cropping practices. Productivity levels are only modest. Mechanization with tractors helps to alleviate problems due to labour shortage when the interval between harvesting and planting of another crop is very short. This method can be highly profitable by increasing the number of harvests per cycle and when rainfall is poor, it makes it possible to use the whole area available. Perhaps the greatest advantage of tractorization is that it enables farmers to extend the area under crops where a lot of land is available or where it is too difficult to cultivate by hand or draught power because of compacted soi1. The consequences of agricultural intensification for the environment were examined during a one-day meeting in Brussels in June 1990, which was organized jointly by the Academie Royale des Sciences d'Outre-Mer de Belgique and CTA. The main conclusions reached were: - that agricultural intensification leads to economies in land use which are indispensable if the environment is to be saved and restored, and - that there would be no point in protecting the environment by intensive crop practices if these practices lead to other forms of environmental deterioration. The experience of the industrialized countries shows that over-intensification is as harmful to the quality of life and the environment as excessive population growth combined with extensive farming in developing countries. There are no miraculous solutions to agricultural problems. But there is a range of methods that research workers can offer to farmers. However, the excessive use of one method over another, can lead to imbalances and result in the deterioration of the environment. In fact, each of these methods represents a single stone within a whole building and good agriculture requires proper integration of each method with all the other production factors. Good agriculture leads to an increase in production and thus, to economical land-use. It results therefore in the conservation of the natural heritage and safe-guarding the future. Like industrialized countries, developing countries undeniably have the right to agricultural intensification. In the present population context, it is a right to survival. One can only hope that they will not commit excesses that will in turn jeopardize their future. Intensification is of course expensive. 'I'd rather fell some trees than buy fertilizers' said an African; but intensification can be a profitable investment. Nowadays, the disastrous consequences of extensive farming, linked to overpopulation, in the tropical world are evident. In many industrialized countries, it is easy to foresee the even more disastrous consequences of the excesses of intensive commercial agriculture. Faced with problems that can already be identified, if the new farmers of the Third World repeat the same errors, they will be responsible for mortgaging their future for ever. References: *(1) Strategies Alimentaires et Nutritionelles. Concepts - Objectifs - Practiques. Proceedings of a workshop. Edited by R Dellere and J J Symoens, CTA, Academie Royale des Sciences d' Outre-Mer. *(2) Perimetres irrigues villageois en Afrique Sahelienne, J Hecq and F Dugauquier, CTA, 1990. *(3) Petite hydraulique agricole a Madagascar, J Hecq and F Dugauquier, CIA, 1990
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