Evaluation of different promising agroforestry tree species on the soil health in sub temperate sub humid mid hill zone of Himachal Pradesh

Abstract

The present investigation was carried out at the established plantations and laboratory of the Department of Silviculture and Agroforestry, Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni, Solan (H.P.) during the year 2008-2009. The experimental site lies in the mid hill zone of Himachal Pradesh with an elevation of 1250 m above mean sea level. It is located at 30o 51' N latitude and 76o 11' E longitude. The study revealed higher nutrient contents at surface layer D1 (0-15cm) which decreased with increase in soil depths. Among different tree species Alnus nitida registered significantly higher amount of available nitrogen at different soil depths. Phosphorus and potassium varied significantly under different tree species and found highest again under Alnus nitida. Phosphorus was noticed maximum (41.92 kg/ha) at 0-15cm which decreased to 40.40 kg/ha at 30-45cm soil depths. Similar trend observed for potassium where it decreased to about 32.50% at D3 (30-45cm) than at D1 (0-15cm). Irrespective of soil depths, the magnesium content was found highest (330.40kg/ha) under Melia azedarach. Magnesium decreased from 329.70 kg/ha at D1 to 281.40 kg/ha at D3 registering about 15% reduction. Calcium behaved in similar manner which irrespective of depths was registered highest under Alnus nitida plantation. A slight decrease in soil pH was observed as the soil depth increased. It lowered to 6.4 at D3 (30-45cm) from 6.55 at D1 (0-15cm). Organic carbon decreased to about 50% at D3 as compared to its value to D1 depth. Similarly, the soil microbial biomass decreased to more than 50% at D3 than that of D1 depth. Irrespective of soil depths the highest (2.15?g/g) microbial biomass was observed under Alnus nitida.