40. Nitrogen mineralization in semi-arid rangeland: influence of grazing and land use type
Abstract
Mineralization of nitrogen (N) in soil is an important process that controls life on earth. In this study, the monthly pattern of soil mineralization was assessed by using intact soil incubation cores in the upper soil layer (0-15cm). The experiment was conducted in semi-arid rangeland of Tomagh, Balochistan, Pakistan in three land use types: protected, orchard and grazed. The study was conducted from May 2009 to April 2010. Results showed that there was highly significant (P<0.01) response in N-mineralization, N-ammonification, and N-nitrification both on monthly and land used basis. The N-mineralization, N-ammonification and N-nitrification were higher during growing season in the months where there was higher rainfall. Maximum mineralization (0.7602 μg g-1), ammonification (0.7482 μg g-1) and nitrification (0.4879 μg g-1) occurred in orchard area, whereas minimum for the same attributes were recorded in grazed area (0.0291, 0.0200 and 0.0091 μg g-1 respectively). In conclusion, the temperature and moisture of soil were found to be controlling factors for N-cycling. Moreover, grazing in Tomagh semi-arid rangeland exerted significant negative influence on N-cycling.
Keywords: Semi-arid; Ammonification; Nitrogen; Mineralization
