By Henrylito D. Tacio
Sloping Agricultural Land Technology (SALT)
Early 1970s. Upland farmers near the vicinity of the Mindanao Baptist Rural Life Center Foundation, Inc. (MBRLC), a non-governmental organization in Kinuskusan, Bansalan, Davao del Sur, visited the center to share their problems.
Most farmers complained of low production from the crop they were planting. "In the past, we harvested more than three tons of corn from one hectare,"
they recalled. "In a span of ten years, our corn production went down to half a ton per hectare."
After corn yields plummeted, farmers started planting permanent crops like banana, coffee, cacao, coconut and fruit trees. But still, yields of these crops were also very low. The MBRLC made a thorough investigation regarding the problem. Their conclusion: soil erosion.
But low production is not the only problem farmers brought with them to the MBRLC. "Farmers expressed to us that there was a need to have a better distribution of income throughout the year," recalled Steve Musen, MBRLC director.
As most upland farmers practiced the monocropping farming system, there were times during the year when a family had no food to fill their empty stomachs. Worse, they didn't have money to buy food. Still another problem was lack of ready cash for fertilizer, insecticides, and seeds of improved varieties of corn and other crops.
"The new techniques which would improve crop yields called for expensive inputs. Farmers borrowed capital for these inputs and each year the soil needed higher levels of fertilizer because the farmer continued to farm in the same old way - plowing up and down the hill," Musen said. "The continuous loss of topsoil reduced yields to below the break-even point in costs and returns. As a result, farmers incurred debts that they could not pay."
Estimates by the Food and Agriculture Organization (FAO) of the United Nations have shown that 25 billion tons of soil are being washed into the rivers each year. In other drier areas, the topsoil is blown away. In the Philippines, the Department of Environment and Natural Resources (DENR) reported in 1988 that 22 provinces in the Philippines had "alarming" soil erosion rate.
The Environmental Management Bureau (EMB), the DENR line agency, said that an estimated 10,000 cubic meters of arable soil per hectare are eroded annually. Such an amount is equivalent to one meter layer of soil thickness removed per hectare per year.
Musen is deeply concerned about soil erosion and its effects on food production efforts by small Filipino farmers. He laments on the lack of soil conservation pattern in the country.
"You should see those muddy rivers from the air after heavy rains - those are tons of topsoil moving down those rivers," he shakes his head. "Multiply that day after day, year after year and how much had been moved out - tons!"
To fully appreciate the seriousness of the problem, let's review a few basic facts:
Soil is the result of the gradual weathering of rocks and minerals. Soil formation is a very slow process that takes place at the rate of 2.5 centimeters per century.
Topsoil is rich and fertile because of its organic matter content. Plants and animals die, decay, disintegrate, and are incorporated in the soil, making soil fertile and capable of supporting the growth and development of food crops.
Surface or topsoil stores plant nutrients, air, and moisture. Topsoil is the site of intense biological activity: innumerable fungi and bacteria in topsoil break down organic matter and make the soil richer. Topsoil is, therefore, essential to productive agriculture.
The nutrients in soil are crucial to crop production. They are the "food"
of plants and are subject to continuous removal through leaching, volatilization, and erosion.
What nature takes a very long time to form - 2.5 centimeters per century - could be washed away in 20 minutes or less by just one heavy rainfall in areas where the farmers don't use the land carefully.
Soil experts say there is nothing wrong with normal soil erosion. In fact, it is beneficial to man. But accelerated erosion, which is usually caused by man's activities, is harmful to man himself because the soil is lost much faster than it is created through normal geological processes.
Low productivity and high cost of production are the two most common effects of soil erosion. Lester R. Brown and Edward C. Wolf, explained in their paper, Soil Erosion: Quiet Crisis in the World Economy: "The loss of topsoil affects the ability to grow food crops in two ways. It reduces the inherent productivity of land, both through the loss of nutrients and degradation of the physical structure. It also increases the costs of food production.
"When farmers lose topsoil," they said, "they may increase land productivity by substituting energy in the form of fertilizer. Hence, farmers losing topsoil may experience either a loss in land productivity or a rise in costs of agricultural inputs. And if productivity drops too low or agricultural costs rise too high, farmers are forced to abandon their land."
According to Brown, the immediate effects of soil erosion are economic but in the long run its ultimate effects are social.
"When soils are depleted and crops are poorly nourished, people are often undernourished as well. Failure to respond to the erosion threat will lead not only to the degradation of land, but to the degradation of life itself," said Brown.
Musen believes that in the Philippine setting, modern agriculture had gotten "the cart before the horse." He said: "A technology had been developed to grow corn but a technology to preserve soil fertility and prevent soil erosion had been overlooked. Thus, we set out to develop a farming system for upland farmers."
MBRLC calls the system Sloping Agricultural Land Technology (SALT). It is a packaged technology of soil conservation and food production that integrates several soil conservation measures in just one setting.
Basically, the SALT method involves planting of field and permanent crops in 3-5 meter bands between double-contoured rows of nitrogen fixing shrubs and trees to minimize soil erosion and maintain the fertility of the soil.
Examples of field crops are the legumes, cereals, and vegetables.
Permanent crops include cacao, coffee, banana, citrus and fruit trees. In SALT, double hedgerows of leguminous perennials are planted at 4-5 meters intervals on equal-elevation contours. The hedgerows are pruned frequently (every 5-6 weeks when moisture is adequate) and the prunings are applied to the crops as mulch and source of fertilizer.
Every third alley contains perennial crops interplanted in a ground cover to serve as an erosion buffer strip and to increase income potential and diversity. The remaining alleys are planted with annual crops using a legume/non-legume rotation. The soil is not normally tilled after hedgerows are planted.
A study conducted at the MBRLC farm showed that a farm tilled in the traditional manner erodes at the rate of 1,163.4 metric tons per hectare per year. A SALT farm erodes at the rate of only 20.2 metric tons per hectare per year in the same period.
The rate of soil loss in a SALT farm is 3.4 metric tons per hectare per year, which is within the tolerable range. Most soil scientists place acceptable soil loss limits for tropical countries like the Philippines within the range of 10 to 12 metric tons per hectare per year.
The non-SALT farm has an annual soil loss rate of 194.3 metric tons per hectare per year.
Actually, SALT took shape in 1971 when MBRLC started to employ contour terraces in its sloping areas. It, however, found this measure to be laborious and inadequate. A dialogue with local upland farmers gave the MBRLC its work direction.
The SALT scheme was verified in a marginal hilly land with a slope ranging from 18% to 50%. By 1978, SALT was ready for dissemination. Today, SALT is one of Asia's most popular farming systems for the uplands.
The success of SALT led to the development of three more variants: Simple Agro-Livestock Technology (SALT 2), Sustainable Agroforest Land Technology (SALT 3), and Small Agrofruit Livelihood Technology (SALT 4).
SALT 2 is half-a-hectare goat-based agroforestry program with a land use of 40 percent for agriculture, 40 percent for livestock, and 20 percent of forestry. SALT 3, MBRLC's answer to the rapid disappearance of Philippine forests, is a two-hectare model farm which devotes 60 percent of its area to forestry and 40 percent to agriculture. "Where in the world can you find a system in which a farmer plants trees and at the same time farms the same area planted to trees?" asks Palmer.
SALT 4 is the growing fruit trees (durian, mangosteen, rambutan, etc.) and other perennial horticultural crops in half-a-hectare farm. "Fruits can easily be marketed. In addition, fruits can stand the rigors of rotting unlike the easily perishable vegetables and other perennial crops," Musen explains.
SALT is now making its presence in other countries as well, particularly those in Asia.