Soil N-transformation Rates in Two Differently Managed Dry Deciduous Forests of West Bengal, India

Sangita Ganguli, Hema Gupta (Joshi), Kashinath Bhattacharya

N-mineralization is crucial to supply available N for plant growth and productivity in forest ecosystem. A study was conducted to estimate the soil N-transformation rates (N-mineralization and nitrification) in two differently managed dry deciduous forest ecosystems. The study areas included Ballavpur Wildlife Sanctuary (created and protected; 23°39'25"N to 87°41'39"E) in Birbhum district and Garhjungle (natural and sacred; 23°40'54.4"N to 87°40'20.2"E) in Burdwan district of West Bengal, India. Soil samples were collected for an annual cycle divided in three seasons (winter, summer and rainy) during January 2014 to September 2014. Both N-mineralization and nitrification rates were higher in Ballavpur than Garhjungle. The annual mean for N-mineralization rate was 14.9 and 20.5 µg g-1 month-1 and nitrification rate was 11.8 and 16.7 µg g-1 month-1 in Garhjungle and Ballavpur, respectively. N-mineralization and nitrification rates as well as soil moisture content were highest in rainy season and lowest in summer season. These rates were significantly positively correlated with soil moisture and negatively with soil mineral-N content. The result suggested that the variation in the rates soil N-transformations were related to the differences in soil moisture content, nutrient status, organic matter content and vegetation types.