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Imperilled Riches COMMERCIAL AGRICULTURE Agricultural use of some rainforest land proves to be a failure because of the nutrient-deficient, acidic soils of tropical rainforests. Nevertheless, many commercial agricultural projects are still carried out on rainforest lands, although many of these revert to cattle grazing lands after the soil is depleted. Some floodplain regions, like those of the lower Amazon (várzea), are more suitable for commercial agriculture because annual floods replenish nutrient stores. Generally forest clearers use slash and burn techniques to clear land, but on a much larger scale than traditional practices. Instead of burning a mere 2-10 acres (1-4 ha), agriculturalists burn hundreds to thousands of hectares. This slash-and-burn technique is wasteful. Only sometimes are trees with timber value removed before the forest is clear cut and left to dry. Then the area is burned. The burning of the forest releases most of the nutrients locked up in vegetation and results in a layer of nutrient-rich material above the poor soils of the former tropical forest. The cleared area is quickly planted and supports vigorous growth for a few years, after which the nutrient stock is depleted and copious amounts of fertilizer is required to keep the operation viable. Fertilizer may be washed into local streams, poisoning fish and aquatic life. When the use of fertilizer is deemed no longer efficient, the land is abandoned and allowed to revert to scrub. Drought-resistant grasses may move in or cattle ranchers may plant imported African grasses for cattle grazing. The land is now only marginally productive and a limited number of cattle can subsist in the area. When the land is suitable for agriculture, generally large single cash crops like rice, citrus fruits, palms, coffee, coca, opium, tea, soybeans, cacao, rubber, and bananas are cultivated. Some of these crops are better adapted to such conditions and last longer on cleared forest lands. However there are several problems with this type of monoculture (single crop plantations) in the tropics, besides the loss of forest. First, such planting of a single crop makes the crop highly vulnerable to disease and pests, as periodic infestations have shown in Brazil, India, and other places. In natural rainforest widespread infestations are rare because individuals of a given species are widely dispersed. Second, the planting of monocultures can be economically risky with the price fluctuations so common in international commodities markets. The cultivation of some of these crops in mountainous, watershed areas has adverse effects for the environment, notably the alteration of water cycles and erosion. In Peru, the cultivation of coca plants (containing the basic ingredient for cocaine) was so widespread in the Andean foothills during the 1980s and 1990s that Peruvian river flood cycles were altered in some areas making the high water season unpredictable. The most serious environmental concern (other than deforestation) stemming from the cultivation of coca is the dumping of chemicals (including kerosene, sulphuric acid, acetone, and carbide) used to process coca leaves. However, stopping coca cultivation is nearly impossible due to simple economics: no crop outperforms coca. The CIA claims that some 600,000 hectares of forest are cleared annually for coca and opium poppy cultivation. Large scale commercial agriculture takes up the majority of the productive floodplain and volcanic soils, while leaving smaller farmers little choice but to cut farmland from the rainforest. The ownership of these large commercial farms is concentrated in the hands of a wealthy minority, who may benefit from tax incentives to leave some of their land fallow and not fully employed at any given time. These large farm businesses generally do not employ large numbers of locals though when they do, workers are used seasonally for low wages. In recent years, grain production in Brazil and other Latin American countries has widely accelerated. However, most of the money ends up in the hands of a few large landowners who have relied on subsidies to survive the harsh soil and climate conditions. Only through these handouts have these landowners been able to turn a profit. Sustainable Agriculture in the Rainforest |
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