UPLB Research and Extension News

The use of herbicide has been found by a group of scientists to prevent soil erosion, preserve soil structure and ensure the replenishment of its fertility.

A research team, headed by Gil Magsino of the University of the Philippines at Los Baños, said one way of controlling soil erosion is through the use of agricultural technology to conserve soil health and prevent its erosion, especially during storms and floods.

“Soil is the most important element of human existence, for it is where agriculture is based. It is a well-known fact that degraded land or sloping areas are more prone to flooding.  Eroded soils pollute the environment,” Magsino said.

Magsino made the remarks as the scientific panel reported the results of the fourth year of the five-year study entitled “Sagip-Lupa: Soil Conservation Technology and Weed Management.” The study tracked herbicide use over four years in demo sites in Benguet, Batangas, Quezon, Isabela and Nueva Ecija, and concluded that the use of herbicides dramatically reduced soil erosion by minimizing hand weeding and tilling.

Traditional weeding and tilling methods break up and loosen the soil structure.

Other methods for conserving soil health, like introducing a legume into the rotation, were also discussed during the event.

Magsino said that crops are only vulnerable to weeds during the first third of their life span, so when crops are already big enough, the presence of weeds is actually beneficial since their roots stop the soil from being easily eroded.

His team members revealed their findings to agriculturists and agricultural committee members at the provincial, municipal and barangay levels through a lecture and field tour conducted on Jan. 14, at the Gladiola Center of the Benguet State University and at the Benguet demo and study site in Long-long, La Trinidad.

The fourth-year report on herbicide use is timely, as the provincial government of Benguet promotes the rehabilitation of the upland farms adversely affected by the recent typhoons and floods.

Benguet’s provincial government is seeking scientific solutions to avoid the recurrence of the floods and sustain the productivity of vegetable farms in the Cordilleras.

The Cordilleras is the main source of vegetables in the country and is known as the “salad bowl” of the Philippines, with Metro Manila as its main market.

The study focuses on the specific use of the herbicide paraquat at 3 liters per hectare in the demo sites.

Results showed significant soil-erosion reduction in all Sagip-Lupa (SL) sites as compared with Farmers’ Practice (FP).

SL percent soil-erosion reduction over FP in Quezon over a period of four years was 62.59 percent, 61.42 percent in Batangas, 49.08 percent in Benguet and 64.47 percent in Isabela compared with FP.

All sites registered soil erosion below the Food and Agriculture Organization (FAO) threshold of 40 tons per hectare of soil over the past four-year period.

The herbicide action, which is limited to destroying the parts of the weeds above-ground, but keeps its root systems intact to hold the soil together, further prevents the dissipation of nutrients from the soil itself, thereby promoting the soil’s nutrient content and fertility.

SL treatment in all sites contributed to reducing input costs (based on tillage practices only). SL-cost savings over FP were a whopping 65.3 percent for cabbage and 67.3 percent for potato in Benguet, 38.6 percent in Quezon, 20 percent for upland rice and 28 percent for corn in Batangas, 33.6 percent in Isabela and 44.5 percent in Nueva Ecija.

“Increase in yield could be attributed to accumulated OM [presence of top soil green algae during the first 45 days after planting],” the report stated. “Absorption of nutrients available in the soil surface and nitrogen available due to OM could be attained if soil erosion was reduced in these hilly SL sites.”

On account of its potency, paraquat should be handled by trained technicians and local distributors are currently working toward full compliance with the regulatory requirements imposed by the Fertilizer and Pesticide Authority on this professional farm input to make it available to farmers in the Cordilleras.