Effect of Arachis pintoi introduction on soil variables in native grass pastures in the Mexican humid tropics

摘要

Native grass pastures account for 25 to 75 % of grazing lands in the Mexican humid tropics used for cow-calf and dual-purpose systems. These pastures have low productivity due to low soil fertility. Arachis pintoi is a persistent legume that effectively fixes N2, and is adapted to hot, humid tropical climate conditions as well as to low fertility, acid soils. Introduction of A. pintoi into native grass pastures was proposed as the best way to improve sustainable cattle productivity. Three and a halfyears after its introduction, soil under the native grass pasture + legume (NG+Ap) treatment showed slightly higher C levels than that under the native grass only (NG) treatment. Initial C value (1998) to 0.2 m depth was 24.7 t/ha, with a mean increase up to the year 2000 of 3.7 t/ha/year for the NG and 4.8 t/ha/year for the NG+Ap. The NG+Ap treatment added 60 kg/ha/year of N to the soil. Bulk density was unaffected by the treatments, with a mean of 1.21 g/cm~3. It is concluded that C and N soil contents increase from introduction of A. pintoi may be an environmental bonus for pasture agroecosystems in the Mexican humid tropics.