Author : Salang, Eriberto D.

Summary : This study is focused on tillage and cropping systems effects on sequestered soil organic carbon (SOC) in Faraon and Adtuyon soils of Zamboanga Peninsula. The tillage systems were no-tillage-no-plowing/harrowing, vegetative residues retained on the surface, and planting was done in drill slot; conservation tillage-one plowing to 15 cm depth and one harrowing, vegetative residues retained and incorporated; and conventional tillage-two plowing to 15 cm depth and two harrowings with off-baring and hilling up, and vegetative residues removed. The cropping systems were classified as annual cropping-corn, corn-legume rotation, vegetables, and rootcrops; covercrop and forage cropping-calopogonium cover crop, and pasture; and perennial cropping-banana and fruit crops. Results showed that sequestered SOC was higher in no-tillage and in conservation tillage than in conventional tillage at Faraon soil. However, only no-tillage had significantly greater SOC among tillage systems in Adtuyon soil. Likewise, SOC was higher in soils under cover crop, forage, and perennial cropping systems. Generally, tillage systems have significantly affected the sequestered SOC. No-tillage had conserved the carbon stock in soils, while conservation tillage maintained the level of soil carbon. However, conventional tillage system reduced the carbon stock as this type of tillage exposed soils in the elements of weather for more decomposition of soil organic matters. Carbon sequestered by soils through no-tillage farming, conservation tillage, covercrop, forage and permanent cropping systems appeared to have great potential for carbon trading to mitigate climate change.