Already in early colonial times, perceptive observers commended the intricate and careful cultivation methods of 'native' inhabitants (see Box 3.2). Classic studies of Asian and African agriculture were made in the 1940s and 1950s, e.g. de Schlippe (1956), Conklin (1957), Allan (1965). A growing number of publications are now appearing about indigenous knowledge systems and the farming systems based upon them (e.g. Brokensha et al. 1980, Biggs & Clay 1981, Rhoades 1984, Richards 1985, Marten 1986, Wilken 1987, Warren et al. 1989, Dupre 1990), which reveal their complexity and sophistication in dealing with environmental hazards.
The following examples of indigenous practices illustrate how well farmers in the tropics learned to manipulate and derive advantage from local resources and natural processes, applying the principles of agroecology without knowing that this term exists. The principles of agroecology as discerned by scientists will be presented in Part II of this book, but first let us take a look at some of the practical applications evolved by farmers through a process of informal research and development.
Forest gardens. In many parts of the humid tropics, indigenous systems of forest gardening (silvihorticulture) have been developed. For example, village agroforests have existed in Java since at least the 10th century and comprise today 15-50% of the total cultivated village land. They represent permanent types of land use which provide a wide range of products with a high food value (e.g. fruits, vegetables, meat, eggs) and other products, such as firewood, timber and medicines. In their small plots, often less than 0.1 ha, Javanese peasants mix a large number of different plant species. Within one village, up to 250 different species of diverse biological types may be grown: annual herbs, perennial herbaceous plants, climbing vines, creeping plants, shrubs and trees ranging from 10 to 35 m in height.
Livestock form an important component of this agroforestry system - particularly poultry, but also sheep freely grazing or fenced in sheds and fed with forage gathered from the vegetation. The animals have an important role in nutrient recycling. Also fish ponds are common and the fish are fed with animal and human wastes.
Natural processes of cycling water and organic matter are maintained; dead leaves and twigs are left to decompose, keeping a continual litter layer and humus through which nutrients are recycled. Compost, fishpond mud and green manures are commonly used on cropland. These forms of recycling are sufficient to maintain soil fertility without the use of chemical fertilisers. Villagers regulate or modify the functioning and dynamics of each plant and animal within the system (Michon et al. 1983).
Shifting cultivation. All over the world, shifting cultivation, also called swidden agriculture, has been and still is practised to manage soil fertility. Shifting cultivation involves an alternation between crops and long-term forest fallow. In a typical sequence, forest is cut and burnt to clear the land and provide ash as 'fertiliser' or 'lime' for the soil. Crop yields are typically high for the first few years but then fall on account of declining soil fertility or invasion of weeds or pests. The fields are then abandoned and the farmer clears another piece of forest. The abandoned field is left to fallow for several years or decades and thus has a chance to rebuild fertility before the farmer returns to it to start the process again.
Shifting cultivation is often characterised by a season-to-season progression of different crops which differ in soil nutrient requirements and susceptibility to weeds and pests. For example, the Hanunoo in the Philippines plant rice and maize the first year after clearing, then root crops such as sweet potatoes, yams and cassava, and finally bananas, abaca (Musa textilis), bamboo and fruits (Conklin 1957).
Shifting cultivation practices throughout the world vary immensely, but there are basically two types of systems:
Transhumant pastoralism. Where livestock are kept in regions with large seasonal differences in precipitation and temperature, a rational low-external-input management form is to move the livestock with the season. American ranchers use winter and summer pastures; shepherds in European mountain areas use alpine and valley pastures; African pastoralists use wet-season and dry-season pastures. Traditionally, pastoral peoples, such as the Fulani in West Africa, keep their livestock in more arid areas during the wet season, where forage quality is relatively high (Breman & de Wit 1983). In the dry season, when water becomes scarce in the north, they move their animals further south to more humid areas, where the livestock can graze the crop residues in harvested fields and the still-green grass in low-lying areas along streams and rivers. These herds are important sources of manure for arable farming. However, this system of resource use was disturbed by the drawing of national boundaries, the setting up of wildlife reserves and commercial ranches (usually in the best grazing areas), and the expansion of cash cropping as well as subsistence cropping to support rapidly growing populations. Especially, the cultivation of low-lying areas with crops, such as rice, is depriving transhumant pastoralists of vital dry-season grazing areas for their herds.
Integrated agriculture - aquaculture. Particularly in Asia, the productive use of land and water resources has been integrated in traditional farming systems. Farmers have transformed wetlands into ponds separated by cultivable ridges. An outstanding example is the dike-pond system which has existed for centuries in South China. To produce or maintain the ponds, soil is dug out and used to build or repair the dikes around it. Before being filled with river water and rainwater, the pond is prepared for fish rearing by clearing, sanitising and fertilising with local inputs of quicklime, tea-seed cake and organic manure. The fish stocked in the pond include various types of carp, which are harvested for home consumption and sale. Mulberry is planted on the dikes, fertilised with pond mud and irrigated by hand with nutrient-rich pond water. Mulberry leaves are fed to silkworms; the branches are used as stakes to support climbing vegetables and as fuelwood. In sheds, silkworms are reared for yarn production. Their excrements, mixed with the remains of mulberry leaves, are used as fish feed. Sugarcane plants on the dikes provide sugar, young leaves are used to feed to fish and pigs, and old leaves to shade crops, for roofing thatch and for fuel; the roots are also used as fuel. Grass and vegetables are also grown on the dikes to provide food for the fish and the family. Pigs are raised mainly to provide manure but also for meat. They are fed sugarcane tops, byproducts from sugar refining, aquatic plants and other vegetable wastes. Their faeces and urine, as well as human excrement and household wastes, form the principle organic inputs into the fish pond (Ruddle & Zhong 1988).
Indigenous farmers have developed various techniques to improve or maintain soil fertility. For example, farmers in Southern Sudan and Zaire noticed that the sites of termite mounds are particularly good for growing sorghum and cowpea (de Schlippe 1956). Farmers in Zaachilla, Mexico, use ant refuse to fertilise high-value crops such as tomatoes, chili and onions (Wilken 1987).
In Senegal, the indigenous agrosilvopastoral system takes advantage of the multiple benefits provided by Faidherbia (formerly Acacia) albida. The tree sheds its leaves at the onset of the wet season, permitting enough light to penetrate for the growth of sorghum and millet, yet still providing enough shade to reduce the effects of intense heat. In the dry season, the tree's long tap roots draw nutrients from beyond the reach of other plants; the nutrients are stored in the fruits and leaves. The tree also fixes nitrogen from the air, thus enriching the soil and improving crop yields (see Table 3.1). In the wet season, the fallen leaves provide mulch that enriches the topsoil, as well as highly nutritious forage. The soil is also enriched by the dung of livestock which feed on the F. albida leaves and the residues of the cereal crops. These benefits are extremely important in places where few alternatives exist for improving soil fertility, crop yields and animal nutrition (OTA 1988).
Traditional practices of biological pest control have recently been the subject of increasing scientific interest, and some interesting examples have been documented. For example, a century-old practice among citrus growers in China is to place nests of the predacious ant (Oecophylla smaragdini F.) in orange trees to reduce insect damage. The citrus growers even install interconnecting bamboo rods as bridges for the ants to move from tree to tree (Doutt 1964). Ducks, fish, frogs and snakes are traditionally used to control insects in paddy rice cultivation. Traditional crop selection, planting times and cultivation practices often reflect efforts to minimise insect damage (Altieri 1987, Thurston 1990).
In innumerable traditional systems, living and hiding places for natural enemies of crop pests are maintained by conserving part of the natural environment. In Sri Lanka, large trees and wooded upland were traditionally left standing around the paddy tract and threshing floors to provide nesting and resting places for birds, which the farmers regard as the main agents of insect control. When pests appeared, certain rituals were performed. For example, when caterpillars invaded the paddy, an offering of food and light was placed at sunset on an unstable plantain disk fitted to a stake. The light attracted birds. When the birds attempted to perch, the food fell. When the birds went after the fallen food, they saw the caterpillars and ate them (Upawansa 1989).
Farmers in the Usambara Mountains in Tanzania developed a multistorey farming system in which they practised fallowing, intercropping and selective weeding. Young crops do not provide ground cover. The farmers understood that, if weeds are left to grow, they cover the soil, prevent it from heating up or drying out excessively, induce a positive competition which stimulates crop growth, and reduce erosion during rainfall. Later in the season, when the farmers regarded weed competition as negative for crop growth, they did superficial hoeing. They left the weeds on the soil surface as protective mulch, to recycle nutrients and to allow nitrogen assimilation through the bacteria decomposing the plants. The crops could then develop fully. A second generation of weeds was allowed to cover the field completely and produce seed, so as to ensure their reproduction in future seasons. When the dry season started, the field was covered with high weeds. The soil remained moist, soft and rich in humus and was thus in good condition for the next growing season. However, the introduction of the principle of weedfree fields led to the collapse of this system of weed-tolerant cropping, so that fertiliser became necessary to replace the green-manuring effect of selective weeding (Egger 1987).
Traditional agriculture is characterised by its great diversity of genetic resources. Many LEIA farmers are highly skilled in managing this diversity so as to ensure sustainable farming systems. For example, farmers in East Java, Indonesia, deliberately make use of different soybean varieties to ensure a supply of fresh seed.
About 70% of soybean production in East Java comes from dry-season cropping on wetland after rice, while the remaining 30% is produced on dryland during the wet season (Soegito & Siemonsma 1985). Most farmers use local soybean varieties which they generally call 'local 29', referring to variety No. 29, which was introduced from Taiwan to Indonesia in 1924. This variety was maintained at Indonesian research institutes but was not multiplied and distributed after its initial introduction at farm level. The farmers' local varieties have small, green-yellow seeds and mature in about 90-100 days, like No. 29. However, the variation found among farmers' varieties in terms of time to reach maturity and yield levels indicates that 60 years of intensive cultivation has led to the development of many distinct local varieties.
The farmers have difficulties in storing soybean seed so as to maintain its viability for more than about 6 weeks. To obtain good germination and establishment of soybean after wet-season rice, they need access to fresh seed. To achieve this they developed a system called JABAL (Jalinan Arus Benih Antar Lapang), which literally means 'seed flow between fields' (Figure 3.1). Certain villages have specialised in soybean growing on dryland during the wet season. Yields are lower than those of dry-season soybean, but farmers can get a 50% higher price for their wet-season crop.
Not only the local crop varieties but also the numerous local breeds of livestock testify to the skills of traditional livestock-keepers to manage genetic resources. Local breeds are partially a result of natural selection, but they are also a result of deliberate selection for specific traits, above all, for the type of animal that can survive and produce under LEIA conditions. The supposedly 'irrational' marketing behaviour of many livestock-keepers reflects their selection strategies. Animals that are diseased, are weak or have poor mothering qualities are sold; those with proven disease and drought resistance are retained. The animals are also selected to fit into the farming system. For example, in pastoral systems, animals not amenable to herding are culled. Transhumant pastoralists select for animals that can walk long distances. An older animal that knows the route well and keeps the herd going steadily on its way will be kept. Generations of natural and deliberate selection have resulted in local breeds with a high degree of disease resistance or tolerance and capable of subsisting on seasonally scarce and lowquality feed resources (Bayer 1989).
Local climate plays a dominant role in the lives and fortunes of farmers everywhere. Farmers in the tropics have developed several ways of influencing microclimate so as to improve the conditions under which crops and animals can grow. The effects of frost (in tropical highlands), hail, strong wind, extremely dry air and daily peak temperatures on plants and animals can be very great, and buffering these may make the difference between a yield and a complete loss.
Farmers influence microclimate by retaining and planting trees, which reduce temperature, wind velocity, evaporation and direct exposure to sunlight, and intercept hail and rain. They apply mulches of groundcovering plants or straw to reduce radiation and heat levels on newly planted surfaces, inhibit moisture losses and absorb the kinetic energy of falling rain and hail (see Box 3.3). When night frost is expected, some farmers burn straw or other waste materials to generate heat and produce smog, which traps outgoing radiation. The raised planting beds, mounds and ridges often found in traditional systems serve to control soil temperatures and to reduce waterlogging by improving drainage. Also natural dew is manipulated and exploited (Wilken 1987, Stigter 1987a). An ingenious system of microclimate manipulation by Indian horticulturists is described in Box 3.4.
Most indigenous farmers can quickly identify major soil types and properties according to characteristics such as colour and texture. Farmers' assessment of soil properties often goes beyond the inherent fertility to include an assessment of workability and response to amendments. Also economic and geological factors, e.g. distance to the village, slope, water-holding capacity, presence of rocks and irrigation water, may be taken into account. Examples of such sophisticated classification systems in Mexico and Guatemala are given by Wilken (1987).
Eger (1989) describes a system of land-use classification in Burkina Faso based on local farmers' knowledge. He compared the effectiveness of land-use classification on the basis of aerial surveys and laboratory analysis of soil samples with a classification on the basis of local knowledge, and concluded that farmers' knowledge is far superior to the outsiders' assessment of soil qualities for certain crops.
Farmers often know the soil properties in the wider area, and may deliberately use these differences in soil properties to make optimal use of the available resources and to spread risks (see Box 3.5).
Many other examples of effective indigenous farming practices have been described, e.g. related to risk minimisation strategies (Eldin & Milleville 1989), slope management (Wilken 1987, Mountjoy & Gliessman 1988, Rhoades 1988), water management (Pacey & Cullis 1986, Reij 1990, Ubels 1990) and pastoral resource management and animal health care (Mathias-Mundy & McCorkle 1989, Niamir 1990).