Corn Cob Biochar Effects on Tropical Soil Aggregate Stability and Aggregate-Associated Carbon and Nitrogen Contents.

The effects of corn cob biochar on aggregate stability and aggregate-associated carbon and nitrogen of a highly weathered tropical sandy loam were studied. Biochar was applied at 15 and 30 t ha^-1. Incoporation of corn cob biochar at 30 t ha^-1 significantly increased the proportion of larger aggregates (>0.25mm), with a subsequent increase in water stable macro aggregates. Mean weigth diameter and geometric mean weight diameter which are aggregate stability parameters were significantly enhanced by biochar application. The increase in aggregate stability also led to a significant increase in the structural coefficients in the biochar amended soils. Biochar application significantly increased total carbon (TC) and nitrogen (TN) in the macro-aggregates with smaller TC and TN observed in the micro aggregates. In perspective, corn cob biochar has the propensity to decrease soil erosion by increasing the aggregate and structural stability of highly weathered soils of the umid tropics. Also, corn cob biochar could potentially enhance the TC and N contents of tropical soils.