Influence of Earthworm Activity on Soil Fertility in Agroforestry Systems

Abstract

Investigations were carried out to study the effect of earthworm activity Oft fertility status of rainfed red sandy loam soil under Acacia tortilis and Leucaena leucocephalo in association with Stylosanthes hamata and Cenchrus ciliaris. Earthworm casts were more abundant and of larger size around A. tortilis than around L. leucocephala. The pH and EC values increased due to earthworm activity whereas silt and clay contents decreased in the casts. Worm-casts contained 1.2 to 1.7 times more available P₂0₅ and 1.4 to 1.6 times more available K₂0 as compared to the parent soil collected from 15 cm depth. As a result of earthworm activity. 12 g of organic carbon. 39 mg of nitrogen, 19 mg of P20S and 192 mg of K₂0 were added per square metre area around A tortiUs by 64 worm-casts whereas 1.43 g organic carbon. 5.4 mg nitrogen,3.5 mg P₂0₅ and 17 mg K₂0 were increased per square metre around L.leucocephala t S. hamata by 54 worm-casts and 0.87 g organic carbon, 4.9 mg nitrogen, 2.6 mg P₂0₅ and 15 mg K₂0 were increased per square metrearound L. leucocephala + C. ciliaris by 44 worm-casts.