UPLBRDE News Service

Clearing farms of weeds to remove crop competitors is not always beneficial as it reduces soil nutrients and contributes to soil erosion, a study showed.

Dr. Gil Magsino, head of the team that conducted a five-year research on soil conservation through the implementation of zero tillage technology, said the farmer’s conventional way of weed management contributes to soil degradation and erosion, especially in sloping farms.

Magsino said frequent weeding is not necessary, adding that plants need not be free from weeds throughout their life cycle.

“Only during the first one-third of the plants’ life should there be no competition, which means that for a crop that matures in 90 days, only during the first 30 days should these be free from weeds,” he said. The study focused on the use of non-selective contact herbicide paraquat in controlling weeds. The herbicide was used in the demonstration site in La Trinidad, Benguet, one of the project’s five pilot areas in Luzon.

The herbicide, Magsino said, only destroys parts of the weeds located above the soil surface. The root systems remain intact, which help keep the soil’s stability while allowing the accumulation of organic matters that will aid in plant nourishment.

“Because the roots are not destroyed, weed re-growth is normal, but what is unique with this technology is its potential to lessen erosion because no soil tillage is needed which will also retain soil nutrients,” he said.

For the past four years of implementation, the no tillage technology recorded reduction of soil erosion on its demo sites. In Benguet, the amount of eroded soil with the no tillage program was 56.37 tons per hectare, much lower than the 110.7 tons per hectare recorded with the farmers’ traditional weeding and tilling methods. The eroded soil were accumulated on catchment basins and were air dried before these were weighed, Magsino said.

Reduction of farm input costs was also noted in the implementation of the no tillage technology. For cabbage, input cost was lessened to P6,870 per hectare from an expense of P19,800 per hectare, while costs for potato was reduced to P6,170 from P18,900.

The research team was composed of scientists from various state universities and colleges in Luzon. The project began in 2005 and will end this year.

Magsino, who led the team, is an assistant affiliate professor at the University of the Philippines Los Baños in Laguna.