PARADIGM SHIFTS IN AGRICULTURAL DEVELOPMENT

PARADIGM SHIFTS IN AGRICULTURAL DEVELOPMENT

TRADITIONAL FARMING SYSTEMS

Farmers in large parts of the tropics have no tradition of aiming at maximum production per hectare and their main concern was to reduce the risk of crop failure. The principal reason is that there were no convenient markets for food surpluses. The traditional farming systems were integrated, based on self-sufficiency and hence on internal supplies and services between different farm components: mixed cropping with a legume supplying nitrogen to a cereal, field crops supplying fodder for livestock in exchange for manure, etc. However, in the last century these systems proved to be not sufficiently productive to feed the rapidly growing population. These traditional systems were not touched by agricultural science, which was the driving force for ever-increasing yield levels in the temperate zones of the world. Agronomists neglected the traditional mixed farming systems for two reasons: (1) the prevailing notion that the market economy demands specialization, and (2) the lack of suitable research methods to study the intricately interwoven farm components.

GREEN REVOLUTION

Modern agricultural science, in spite of its roots in systems research, gradually became very much preoccupied with the improvement of single crops. When called upon to combat hunger in tropical regions, agronomists concentrated on raising the yield of the principal annual staple food crops such as rice and wheat. These crops were already grown as monocrops for the market and lent themselves to the approach which had been so successful in the temperate zones. Agronomists indeed succeeded with these crops, as for instance shown by the 'green revolution' in Asia.

LOSS OF NATURAL VEGETATION 

Unfortunately, green revolution did not benefit poor farmers and this approach failed to alleviate hunger, in particular in tropical regions with rainfed farming systems and underdeveloped markets for food crops. In those regions the situation continued to deteriorate, also because the prices of non-food commodities (e.g. cotton, coffee, spices, fibres) kept falling worldwide, strapping small-holders of cash income and reducing them to subsistence levels of farming. Mounting population pressure resulted in ever-smaller farm size and need to sacrifice unproductive trees in favour of planting food crops. Moreover, the inability to raise yield levels forced the growing population to bring more land (often marginal land) under cultivation at the expense of the natural vegetation.

DETERIORATION OF LAND USE SYSTEMS

Before long, these trends led to alarming reports about deteriorating land use systems (1) expanding dust bowls and deserts (because of wind erosion). (2) degraded land following loss of topsoil and silting up of irrigation systems (because of water erosion), and (3) declining soil fertility and yield levels (because of inadequate inputs of manure and fertilizer and the opening up of marginal lands). And then it was realized that these precarious situations had something in common: "Trees were vanishing from the Landscape". Deforestation to open more arable fields, trees and shrubs killed by overgrazing, cutting of trees for fuelwood, etc. all added up to a landscape being denuded of its permanent vegetation (mainly forests and grazing land for cattle).

NEED FOR TREES IN AGRICULTURAL DEVELOPMENT

Thus, it became clear that trees not only yield useful products but also play a vital role as more permanent elements in the landscape, sustaining the capacity of the land to feed people. This brought trees onto the agenda of agricultural development. Although trees are the largest perennial plants and they exhibit the qualities which are important in sustaining the productive capacity of the land, the most important factor is that permanent vegetation or woody plants cover the land, whether it consists of trees, shrubs, vines or perennial herbs (grasses, plantain. yams, etc.).

BIRTH OF AGRFORESTRY SCIENCE

Unfortunately, the benefits of a permanent vegetation cover of trees and other perennials only become obvious when the land has been denuded under excessive population pressure, overgrazing and deforestation. Once the elements have free play over the bare land. 'regreening' becomes very difficult because only the hardiest of plants can reclaim the area and these tend to produce little in the way of food for man and animals. It is therefore of the utmost importance to reverse this overexploitation process before land degradation has impoverished the people who live in the area. Annual crops cannot provide permanent cover and in dryland farming the fields lie a large part of the year unprotected. The realization that these annual crops should benefit from suitable combinations with tree crops in mixed cropping systems, gave rise to AGROFORESTRY as a distinct discipline in agricultural science in the 1970s. Further consideration of the role of trees, shrubs and vines in mixed cropping systems resulted in the inclusion of crop mixtures of woody plants as well as cropping systems combining woody plants and animal husbandry.

PREFERENCE FOR AGROFORESTRY OVER MIXED FARMING

Meanwhile agricultural science had rediscovered its origin dating back to the early 19th century in farming systems in the tropics. Crop science had already extended its reach from single crops to the study of mixed crops. This research confirmed the farmer's claim that mixed cropping reduces the risk of crop failure, but it also dampens the response to crop care. The outcome of the research on comparison of simple crop mixture (e.g. maize and beans grown together) over two plots of maize and beans grown separately, is not spectacular at all. The mixture yields only slightly more than the sum of the two crops on their own and the total yield of the mixture is more stable from year to year.

Compared to the interactions between maize and beans in mixed cropping, the interactions in agroforestry systems are a good deal more complex. Moreover, trees require years before they reach an effective size. During these years their interactions with companion crops and/or livestock keep changing. The result of agroforestry technology is the reversal of a downward trend in land use into an upward trend, putting land-use back on a sustainable basis. Farmers adopt agroforestry practices for two reasons. They want to increase their economic stability and they want to improve the management of natural resources under their care.