Improvement of agricultural methods and productivity to reduce the need to cut down additional forest land. Tropical forests cannot be maintained unless agricultural productivity is greatly improved. However, to feed the projected population of the mid-21st century even at present levels, not to mention a level approaching that of developed countries, agricultural efficiencies would have to be far greater than is currently the case in most countries. We need increases in agricultural productivity of between 1.8% and 3% per year for many years. The average annual growth rate of agricultural productivity in Sub-Saharan Africa between 1991 and 1995 was 2.4%, which must be maintained to prevent a decline in nutritional levels as populations grow (Musters, de Graaf, & ter Keurs, 2000). To provide levels of nutrition equivalent to more developed countries, still higher production growth rates will be necessary. This can occur only if technologies are greatly improved and substantial financial support is provided by wealthier countries. Without such development, conservation strategies are doomed merely by arithmetic.
It is argued that, with proper techniques, including irrigation, sustainable agriculture can be established on former rainforest soils (soybeans in the Brazilian Amazon, for example). Of course, sugar has been raised in the Caribbean and rice has been successfully cropped for thousands of years in Southeast Asia on tropical forest soils. This type of agriculture is possible where soils are fertile, as in the regions of Indonesia which have rich volcanic soils. But elsewhere, as in East Java, only the most marginal agriculture (raising tapioca and other low-nutrient tubers) is possible, and these areas are extremely poor. Some nonvolcanic rainforest areas lie on reasonably fertile soils (especially in deltas) and can sometimes sustain appropriate crops. Recently, archeologists have discovered the remains of ancient agricultural systems in the Beni region of Bolivia. These artefacts lie in seasonally-flooded savannas which have long been thought to be useful only for cattle ranching. However, the many raised agricultural fields, fish ponds and other agricultural constructions indicate that these areas have been productive in the past. Recently, the construction of similar raised fields in savanna areas in Bolivia has permitted the cultivation of tubers, maize, and manioc (Mann, 2000). If more of these areas could be converted to productive agriculture, they could provide a source of land as an alternative to rainforest removal. Often, however, governments encourage and indeed, almost coerce the development of unsuitable agricultural products, although they should not attempt to introduce non-native species and unsuitable crops or domestic animals into forest areas. For example, the Peruvian government has aggressively promoted the introduction of rice cultivation and water buffalo husbandry into many areas of the Amazon rainforest. In most places, rice is a most unsuitable cultivar, and water buffalo have caused serious erosion of riverbanks and destruction of vegetation.
To improve agricultural productivity, a number of things must be accomplished:
a. Reduction of the present rate of degradation and loss of productive farmland due to erosion, salinization, waterlogging, and nutrient depletion: Technologies for these purposes are available, but are little used because of the expense. However, many non-technological methods have been used for years by farmers (contour plowing, abandonment of marginal agricultural lands, planting of wind barriers, fallowing). Erosion can be prevented by the careful selection of appropriate crops, keeping ground cover on the soil, and contour plowing. Irrigation increases crop yields by about 200%, so more land must be irrigated to increase production efficiency, but this uses great quantities of water. More efficient methods must be utilized to prevent water shortages, as only 45% of irrigation water is actually absorbed by plants. Drip irrigation and other efficient delivery systems, better water distribution systems, improved control systems, and raising crops suited to the climate and soil will aid in this endeavor. Excessive or continual irrigation leads to salinization and waterlogging of the soil, which will diminish or destroy its agricultural capacity.
b. Raising the crop yield on current agricultural land, as most land is not producing yields even close to the maximum possible (in part because modern technologies are not used). If the gap between current and potential yield could be bridged, the production of soybeans could be increased by 64%, that of peanuts by 208%, pulses by 472%, and cereals by 170% over a period of several years. The theoretical maximum yield for cereals is 13.4 tons per hectare, but the average cereal yield (1992-1994) was 2.77 tons per hectare – not even close to this figure (Goklany, 1998). There are regional inequities as well. Yields tend to be much lower in the tropical developing countries with large, growing human populations. For instance, in Subsaharan Africa, yields of cereal grains are only one-third of the cereal yield in the northern hemisphere. Increasing yields can raise income for marginal agriculturalists and reduce dependence upon destructive slash-and-burn agricultural methods. This may be done by improving tillage methods to preserve soils and nutrients, which will be more beneficial than removing rain forest to open more agricultural land. Other techniques might include soil testing to determine soil chemistry profiles, crop rotation, nutrient and water management, terracing, instituting appropriate tillage methods for the soil/terrain, crop diversification, and interspersing crops with trees. These methods could reverse the nutrient depletion characteristic of so many cultivated soils in tropical areas. To increase productivity, one must also reduce losses from disease and pests, both during growth periods and after harvest (currently an average of 42% of crop yields is lost to these agents [Goklany, 1998]). Pest and disease-resistant varieties, better storage facilities and improved transportation could help in this, as well as the development of new high-yield crop varieties, suitable to local weather and soil conditions. Except for the “green revolution” with rice, less effort has been put into the development and study of tropical crops than temperate ones.
c. Reforming agricultural practices to be less harmful to forests and forest regeneration: Among these reforms could be reductions in the use of burning, minimizing the use of toxic chemicals, and using swidden land less intensively by increasing fallow times. Zero tillage agriculture should also be utilized. When the soil is left untilled, organic matter is retained, preserving soil fertility and preventing erosion and runoff. Where the soils contain organic matter, forests can often regenerate.
d. Improving the distribution of agricultural products: Distribution systems are extremely unequal in most tropical countries, and often unreliable. Access to food and other agricultural goods must be increased in terms both of availability (delivery) and affordability.
e. Reduction of the environmental impacts of new technologies. To diminish environmental impacts, agricultural management systems must be devised which are suitable for specific areas and crops. This would allow reduction in artificial inputs, so that fertilizer and pesticide use could be considerably reduced.
f. Reformation of policies relating to water management, allocation, and distribution. For instance, governments will frequently subsidize water use for agriculture, reducing incentives for water conservation. That users pay fairly for water is essential (now, frequently, the poor pay more for water than the rich). Many countries have achieved considerable water conservation by this method (Chile, Jordan, India and others), and it could certainly be applied by most tropical countries.
g. Retention of trees as crops to protect water and soil resources. In southern Malaysia, 60% of the forested area has been kept in forest, while the other lands are used for agricultural purposes (Spears, 1988). How much of this land will remain protected with increasing demand for palm oil and other products is questionable, however.
h. Development of agroforestry projects: Cash crops might be raised in small-scale agroforestry plots. Such crops as avocados, papayas, peppers, palm fruits, mangos and many other local crops are being raised in this way in the Amazon. According to Spears (1988), the need for industrial wood could be provided by tree plantations of approximately 25 million hectares, about 10% of the remaining forest area, but as of the date of the article, only 2.6 million hectares of such plantations had been established. They could preclude the need to remove virgin forest, particularly if they consist of rapidly-growing species. Such projects can act as alternatives to the expansion of agricultural areas.
i. Provision of a system of tropical agricultural research stations and, especially, agricultural extension workers and soil experts to assist local farmers. This is absolutely essential for the success of agricultural reform. If farmers don’t know or understand the methods, nothing can be improved.
j. Provision of governmental guidance and regulation: The “green revolution” was successful and widespread only partly because of the dispersal of information to virtually all rice-growers. In addition, some coercive regulation was undertaken by governing bodies – usually local – in some places. In Bali, for instance, water for irrigation is provided only to those farmers who use the new varieties of rice.
Some of these scenarios require that new technologies be developed, others do not. All of these changes require that economic benefits accrue to farmers to provide them with incentives for using different technologies and methods, and for using them effectively. Economic and scientific aid will be required from international agencies as well as national governmental agencies in order to assure that any changes made are sound, adapted to local conditions, and environmentally safe.