Text and Photos by Henrylito D. Tacio
“The multiple roles of soils often go unnoticed. Soils don’t have a voice, and few people speak out for them. They are our silent ally in food production.” — Jose Graziano da Silva, director-general of the Food and Agriculture Organization
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Sales Batawan was a total stranger to the area, which is located 86 kilometers away from Davao City. He came to Pananag, a small village in Bansalan, Davao del Sur, when his wife’s father requested him to help him in his farm.
At first, farming was good. But as years went by, production was all-time low. His income from the farm was not enough to feed his family. “I never finished high school and I have six children to feed,” Sales pointed out.
To make both ends meet, he had to work as a sugarcane laborer for his neighbors. In some instances, he had to travel far just to earn extra cash. “If I solely rely on my farm’s income, my family will starve,” he said.
He observed that the farm he is tilling is now teemed with small rocks. Unlike in the past, he had to put a lot of commercial fertilizer in order for him to harvest some of the crops he had planted.
Probing deeper, the problem is not production but the land he is farming. It is now devoid of topsoil, whose nutrients are crucial to crop production as they are the “food” of plants and other organisms.
Topsoil is subject to continuous removal through leaching, volatilization and erosion. What nature takes a very long time to form could be washed away in 20 minutes or less by just one heavy rainfall in areas where farmers don’t use the land carefully.
Under most conditions, soil is formed at a rate of one centimeter every 100 to 400 years, and it takes 3,000 to 12,000 years to build enough topsoil to form productive land.
“Topsoil is rich and fertile because of its organic matter content,” explains Roy C. Alimoane, the director of the Mindanao Baptist Rural Life Center (MBRLC), a non-government organization which has been promoting farming systems on saving the topsoil from erosion. “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.”
Soil experts say there is nothing wrong with normal soil erosion. “Under normal conditions, each hectare of land losses somewhere between 0.004 and 0.05 tons of soil to erosion each year – far less than what is replaced by natural soil building processes,” one study reported.
But accelerated erosion, which is usually caused by man’s activities, is a different story. Soil is lost much faster than it is created through normal geological processes. “No other soil phenomenon is more destructive worldwide than is soil erosion,” wrote Nyle C. Brady in his book, The Nature and Properties of Soils. “It involves losing water and plant nutrients at rates far higher than those occurring through leaching. More tragically, however, it can result in the loss of the entire soil.”
In the Philippines, water plays a major role in causing massive soil erosion. According to science writer Martin A. De Harte, there are four types of soil loss brought about by moving water: rill, sheet, gully, and streambank erosion.
Rill erosion is caused by water running down a slope which then creates small channels in the topsoil. When soil is removed in a uniformly thin layer, it is referred to as sheet erosion.
“The farmer may not notice sheet erosion happening because only small amounts of soil are removed from the surface of his field at a time,” De Harte explained. “After several years, however, his crop production will decline seriously, especially if he doesn’t apply fertilizer.”
When a large volume of water flows through the same channel all the time, a gully is created. Gully erosion obliterates the topography of both lowland and upland areas. Wide and deep gullies have created large ugly cuts in the mountains and plateaus of Bukidnon, Masbate, Cebu, Ilocos Norte, and Abra.
Caused by heavy floods, streambank erosion occurs in almost all parts of the Philippines. Over the years, floods have eaten deep into the banks of Cagayan, Agno, Pampanga, Rio Grande, and Davao Rivers.
When soil is eroded, it is gone forever. “Soil erosion is an enemy to any nation – far worse than any outside enemy coming into a country and conquering it because it is an enemy you cannot see vividly,” said Harold R. Watson, an American agriculturist who received a Ramon Magsaysay Award in 1985 for peace and international understanding. “It’s a slow creeping enemy that soon possesses the land.”
In 1988, the Department of Environment and Natural Resources (DENR) reported that 22 provinces in the country had “alarming” soil erosion rate. Batangas in Luzon and Cebu in Visayas had been reported to have lost 80-85% of their topsoil to erosion. Marinduque had 75-80% soil erosion while Ilocos Sur and La Union had 60-70%. Zamboanga del Sur, Zamboanga del Norte, Lanao del Norte, Lanao del Sur, Misamis Oriental, Bukidnon, North Cotabato, South Cotabato, Davao del Sur, Davao Oriental, Davao del Norte, Negros Oriental and Occidental, Iloilo, Aklan, Capiz, and Antique had more than 50% of their soil eroded.
“Soil erosion is a quiet crisis, an insidious, largely man-made disaster that is unfolding gradually,” Dr. Noel D. Vietmeyer wrote in the foreword of the book, Vetiver Grass: A thin green line against erosion. “In many places it is barely recognized; the soil moves away in such small increments from day to day that its loss is hardly noticed. Often the practices that cause the greatest losses in the long term lead to bumper crops in the short term, thereby creating an illusion of progress.”
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 book, 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,” the two authors continued, “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.”
Brown, in another book, believes 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,” he stressed. (To be concluded)
