Abstract

Organic carbon, nitrogen, phosphorus and potassium availability in the soil under multipurpose tree cropping system in Andhra Pradesh were estimated. The results revealed that the soil organic carbon and nitrogen content were higher in Pongamia pinnata tree based systems due to accumulation of plant residue, its decomposition, high N fixation rate and increased availability of nutrients in the soil due to quick mineralization. Among the multipurpose tree systems, the phosphorus availability under Dalbergia sissoo showed significantly higher quantities. Due to high plant residue and efficient nutrient recycling capacity, the available potassium content under Acacia nilotica cropping systems was high at three depths when compared to the other systems. The organic carbon and major nutrient contents decreased significantly with increased depth due to huge build-up of different nutrients on surface layers than in lower layers.

Keywords: Available C,N, P and K, Agroforestry model