During the first National Soil Health Summit in 2023, President Ferdinand Marcos Jr. admitted that about 75 percent of the country’s “total crop land is vulnerable to erosion in various degrees, with agriculture losing about 457 million tons of soil annually.”
Marcos added, “Our soil is under threat and to continue to neglect this vital agricultural component will lead to even worse crises in the future.”
A recent study by the Royal Commission on Environmental Pollution concluded that approximately 30 percent of the world’s arable crop land has been abandoned because of severe soil erosion in the last 40 years.
“When soils are depleted and crops are poorly nourished, people are often undernourished as well,” authors Lester R. Brown and Edward C. Wolf wrote in Soil Erosion: Quiet Crisis in the World Economy. “Failure to respond to the erosion threat will lead not only to the degradation of land, but to the degradation of life itself.”
It should not happen. the Mindanao Baptist Rural Life Center (MBRLC) has developed a sustainable farming system that helps curtail soil erosion. It is known as Sloping Agricultural Land Technology (SALT), which Harold R. Watson and his Filipino associates had been promoting.
“The principle of SALT is the same as that used by the Ifugao tribes,” explained Harold R. Watson, the man behind SALT and former MBRLC director. “All we are doing is suggesting using nitrogen-fixing trees and shrubs instead of rocks.”
The Municipal Agriculture Office (MAO) in Bansalan, Davao del Sur has recognized SALT as a potential solution for the problem of soil erosion in Balutakay, a sitio located in the rolling foothills of Mount Apo.
“We have observed its effectiveness in various regions of the country,” states MAO officer Zaldy Sumangil. “Therefore, as part of our commitment to prevent Balutakay from deteriorating into a barren landscape and to avert further damage, we trained our farmers to learn the fundamentals of the technology so they can implement it on their farms.”
The SALT system necessitates meticulous management of the spacing between rows of trees and shrubs. It is advisable to implement a combination of permanent, semi-permanent, and annual crops to restore the ecosystem and optimize yields, while also allowing farmers to effectively organize their work schedules.
The two bands of hedgerows of various nitrogen fixing trees and shrubs – which are cut every 15 days to serve as fertilizer and mulching materials to the crops – plays a crucial role in mitigating soil erosion.
A research study conducted at the MBRLC farm indicated that conventional farming methods lead to soil erosion at a staggering rate of 1,163.4 metric tons per hectare each year. In contrast, a SALT farm experiences a markedly lower erosion rate, measuring only 20.2 metric tons per hectare annually during the same period.
The soil loss rate on a SALT farm is recorded at 3.4 metric tons per hectare per year, which is within acceptable limits. Soil scientists typically regard the tolerable soil loss for tropical nations, including the Philippines, to be between 10 and 12 metric tons per hectare per year. On the other hand, the non-SALT farm demonstrates a significantly higher annual soil loss rate of 194.3 metric tons per hectare.
“Soil is related to the earth much as the rind is related to an orange,” commented an American geologist. “It is the link between the rock core of the earth and the living things on its surface. It is the foothold for the plants we grow. Therein lies the main reason for our interest in soil.”
The SALT training was conducted on the first day of the extensive training which the identified Balutakay farmers had to undergo. If the first day training was done at barangay Kinuskusan, where MBRLC is located, the second was done at Balutakay itself.
Allan B. Ampoloquio, who has been trying to save Balutakay from further deterioration, was the invited speaker. He advocates for the use of vetiver grass, locally known as rimoras or moras, as a potential solution.
“While it may not be the definitive solution or cure and may require additional programs or systems to be effective, vetiver, as a living plant, serves as a vegetative barrier against soil erosion and aids in soil and water conservation, which has been documented as successful,” he says.
Ampoloquio believes that employing vetiver grass is a “cost-effective, comprehensive solution for soil erosion, flood control, and groundwater recharge.” He further notes that it “will incur the government a minuscule fraction of the current expenditure on disaster preparedness.”
Vetiver grass is a perennial grass that grows in dense clumps with leaves that are erect, have rough edges, and are rather stiff. Known scientifically as Chrysopogon zizanioides), it is easy to grow with minimal maintenance. Each plantlet can grow up to 30 centimeters in width. The roots can grow from 3 to 4 meters deep, which enables them to control soil moisture and nutrients effectively.
If allowed to grow further for a long period of time, vetiver grass can live up to 10 years. Once established, it is not easily killed by cogon grass. It can be planted as a hedgerow (planted in a row) across the sloping contour of a farm. It forms a dense barrier that slows down and spreads rainfall runoff.
Based on a study conducted by the Central Bicol State University of Agriculture (CBSUA), it was found that vegetable yield in areas with vetiver grass is higher compared to areas not planted with vetiver grass. The presence of vetiver was observed to minimize soil loss in the area.
In Leyte, a study conducted by the Visayas State University (VSU) showed crops like corn and upland rice planted near vetiver hedgerows have performed well. Corn planted near the vetiver grass produced bigger ears than those near the napier grass. The herbage from vetiver grass has been found to be a good mulch for sweet potatoes.
Vetiver grass contributes much to the control of topsoil erosion, VSU reported. The transported soil is accumulated along the vetiver hedgerows where it is trapped. The grass has an expanded/dense base which can serve as a physical barrier preventing soil and water from passing through.
Vetiver grass is not a good soil erosion controller unless A-frame is used in locating the contour line of a sloping farm. Once grown, it does not grow anywhere except in the contour line where it is planted.
“If used as hedgerow in sloping vegetable areas, vetiver occupies just a small amount of space and does not compete with crops in terms of nutrient absorption due to its longer roots,” CBSUA explained in a published booklet on vetiver grass.
The Vetiver Network International states that the vetiver system, when implemented properly, can serve as a significant tool for minimizing erosion (by as much as 90%), conserving and reducing rainfall runoff (by up to 70%), enhancing groundwater recharge, filtering pollutants from water, lowering the likelihood of flooding, and providing economic advantages to communities.
The vetiver grass can be utilized as an effective strategy to avert landslides in sloped regions. In addition, it can also help prevent soil erosion along riverbanks. Findings from a study conducted by VSU indicated that once established, vetiver hedgerows allow less water to pass through during heavy rainfall.
Contour plots have leveled three years after planting vetiver grass. “After four years of planting lines of vetiver grass, the gullies are not visible,” VSU reported.
The Department of Public Works and Highways is implementing the use of vetiver grass in various projects. This grass is utilized to reinforce and stabilize structures, including the edges of roads, bridges, canals, and railways, among others.
Meanwhile, the decision for the Balutakay farmers to adopt either SALT, vetiver grass, or both lies with them. As part of the initiative launched by MAO, the beneficiaries also receive various nitrogen-fixing trees and shrubs, vetiver grass, vegetable seeds, and fertilizers.
“I concur that both vetiver and SALT represent cost-effective and complementary solutions that are appropriate for Filipino farmers,” points out Ampoloquio.
