There is now a technology that enables Filipino farmers to grow trees on their farms while simultaneously planting agricultural crops. The Davao-based Mindanao Baptist Rural Life Center (MBRLC) Foundation, Inc. has created this innovative system.
It is called Sustainable Agroforest Land Technology (SALT 3). It is a modification of the original Sloping Agricultural Land Technology (SALT). SALT 2 refers to Small Agro-Livestock Technology, where farmers can raise goats and still follow the original system.
“SALT 3 is specifically developed for upland farms,” says MBRLC Director Jethro P. Adang. “Farmers can grow different types of trees at the upper portion of their farms. Agricultural crops like corn, vegetables, and cereals are planted at the lower portion.”
Adang explains the rationale behind planting trees in the upper section of the farm, saying, “Cultivating crops on steep terrain presents significant challenges. Additionally, this area is more prone to erosion during rainfall. Plus, it makes harvesting particularly difficult.”
He further notes that the presence of trees in the upper portion aids in mitigating erosion. “The rain’s impact is less damaging as it primarily strikes the leaves of the trees. Also, the water that flows downward does so more gently compared to areas lacking tree cover.”
SALT 3 is a form of agroforestry, defined as “a land management approach that combines agricultural and forestry technologies to create integrated diverse and productive land use systems.”
The original SALT was patterned after the technology developed by the ancestors of the Igorot people in the north. “The principle of SALT is the same as that used by the Ifugao tribes,” Adang says. “All we are doing is suggesting using trees and shrubs instead of rocks.”
The recommended trees and shrubs are ipil-ipil, kakawate, and others that are locally available in the area. Introduced species like Flemingia macrophylla, Desmodium rensonii, and Indigofera anil can also be used as hedgerow species.
When the hedges or rows of vegetation are 1.5 to 2 meters tall, these are cut back to about 40 centimeters and the tops are piled in the 3-5 meter alleys where crops are growing. “The leaves of the shrubs make very good nitrogen-rich fertilizer and also add organic matter to the soil,” Adang says.
SALT 3 is developed for two hectares located in upland areas. The Philippines is geographically an upland country because 60% of its 30 million hectares are classified as such. The uplands are rolling to steep areas where both agriculture and forestry are practiced on slopes ranging 18% upward, according to the Department of Environment and Natural Resources (DENR).
In a two-hectare farm, one hectare is allotted to crop production while the other one hectare is planted to trees.
Adang talked about “tree time zones.” It means trees are planted according to how many they can be grown: 1-5 years, 6-10 years, 11-15 years, and 16-20 years. Those early maturing trees are progressively harvested. The very valuable trees are left longer, which he calls “the grandchild project” as these are planted “for your grandchildren.”
He was referring to narra (Pterocarpus indicus) and acacia (Samanea saman). Below these trees, crops like black pepper, taro, and sweet potatoes can be planted. While the trees are still growing, turkey may be raised to help cut the grasses.
Among the early harvestable trees are ipil-ipil (Leucaena leucocephala), katuray (Sesbania sesban), mahogany (Swietenia macrophylla) and the two species of Acacia (mangium and auriculiformis).
“While waiting for the trees to grow, we advise farmers to plant short-term crops like vegetables, tubers, and crawling plants like ubi and sweet potato,” Adang says.
The recommended boundary crop is bamboo, which helps protect the water from penetrating the agricultural farm down below.
As a source of immediate income, the lower portion of the farm is planted to various crops. Still the concept of the original SALT is followed: two rows of nitrogen fixing shrubs and in between the hedgerows, crops are planted. Every month or so, the hedgerows are cut and the cuttings are placed below the crops to serve as mulching materials and as fertilizer.
Aside from protecting the farm from soil erosion, SALT 3 also helps mitigate the impact of climate change. “By planting trees in your farm, you help create a sink for the carbon dioxide that should have been released into the atmosphere,” Adang says.
A study done by the Department of Environment and Natural Resources (DENR) showed that a single mature tree can absorb carbon dioxide at a rate of 21 kilograms a year and release enough oxygen back into the atmosphere to support two persons.
The study showed that about 1.5 tons of carbon dioxide are removed and 1.07 tons of life-giving oxygen are produced for every ton of newly grown trees.
According to Adang, SALT 3 is specifically developed for the uplands, where at least a fourth of the total population live. Most of these uplands are considered the last frontier as these are the areas where most trees are located.
In the past, upland farmers practiced slash-and-burning agriculture (more popularly known as “kaingin” farming).
But migrant farmers – those who lived in the lowlands before but are now farming the uplands – attack virgin forest lands to cultivate the rich soil, which they quickly deplete. Today, there is no more land where they can move on to.
In the Philippine context, the uplands are rolling to steep lands, with slopes ranging upward from 18 percent. About 60% of the country’s total land area of 30 million hectares are classified as uplands. Most of those living in these areas are farming families in dire poverty and insecurity.
“The upland farmer faces a very dark future unless something can be done for him very soon,” commented American missionary Harold R. Watson, former MBRLC director.
“He is the least educated, least paid, least healthy, least hopeful, and most neglected (in terms of agricultural development) of all people in the Philippines,” said Watson, who received the Ramon Magsaysay Award in 1985 for encouraging international utilization of SALT in Asia.
