A comparative account of the microbial biomass-N and N-mineralization of soils under natural forest, grassland and crop field from dry tropical region, India
2009
Singh, J.S.,Babasaheb Bhimrao Ambedkar (Central) Univ., Lucknow (India). Dept. of Environmental Science | Singh, D.P.,Babasaheb Bhimrao Ambedkar (Central) Univ., Lucknow (India). Dept. of Environmental Science | Kashyap, A.K.,Banaras Hindu Univ., Varanasi (India). Dept. of Botany
This study investigated microbial biomass-N (MB-N) and N-mineralization in soils of four different vegetation systems including forest, mixed forest, savanna and cropland ecosystems in the Vindhyan region, India. A change was noted due to physiographic differences and anthropogenic disturbances. Annually the soil moisture (SM) content across the different study sites ranged from 7.5 to 24.3% being maximum in forest sites compared to savanna and cropland sites. The NH4+-N, NO-3-N and MB-N concentrations varied from 4.3 to 10.2 microg/g, 1.1 to 5.8 microg/g and 21.3 to 90.2 microg/g dry soil, respectively, with minimum values in the wet and maximum values in the dry season. The trend of seasonal variation in net N-mineralization was similar to that of moisture content but counter to the concentrations of inorganic-N and MB-N. The net N-mineralization rates at different investigated sites ranged from 4.5 to 37.6 microg/g month. Cultivation reduced the N-mineralization and MB-N by 58.5% and 63.5%, respectively. The percentage contribution of MB-N to total-N was 8.01 to 19.15%. MB-N was positively correlated with the inorganic-N but negatively with soil moisture and net N-mineralization rates. The order of soil MB-N levels and net N-mineralization followed the sequence: forest more than mixed forest more than savanna more than cropland.
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