Application of in-situ technique to study N fluxes on degradaded soils
TIAN Kun 1, CHEN Bao Kun 2, BEI Rong Ta 2, LUO Kai Hua 2, WANG You Wei 2, YANG Yong Xing 3 (1 The Key Laboratory of Waterlogged Disaster and Wetland Agriculture, Hubei Agricultural College, Jingzhou 434025,China; 2 Department of Environmental Science and Engineering, Southwest Forestry College, Kunming 650224,China; 3 Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, Changchun 130012,China)..
Both soil disturbance and soil utilization type changes markedly affect rates of soil N mineralization. It is generally impossible to assess the usefulness of most estimates of N mineralization as predictors of field rates because of the unknown effects of assay conditions. A methodology for fluxes of mineral N, based on sequential soil coring and in situ exposure of largely undisturbed soil columns confined within metal tube, to research the soil mineral N's release and immobilization, plant up take of N and maximum N leaching on degraded soils in Lancang River watersheds, Yunnan. We show that disturbance can either increase net N mineralization, cause leaching of N and immobilization of N, alter the proportion of nitrate nitrogen produced during incubation, or induce or obscure the effects of previous fertilization on rates of N mineralization. The types changed from broadleaved forest to orchard, slop cropland, eucalyptus and pine coniferous forest, mineral N reduced 51 51,29 64,26 84,16 40 mg·kg -1 within 60 days,and the coefficient of variation was 21 5%, 11 0%, 14 2% and 8 3%, respectively. The immobilization of N was 15 45 mg·kg -1 for orchard, 13 90 mg·kg -1 for eucalyptus and 8 51 mg·kg -1 for slop cropland. The maximum N leaching occurred at the type of slop cropland (44 50 mg·kg -1 ), and followed the types of pine coniferous forest (38 41 mg·kg -1 ) and eucalyptus forest (25 30 mg·kg -1 ). The amount of plant up take of N for different types is orchard slop cropland eucalyptus forest pine coniferous forest broadleaved forest and type of mineral N up taken by plant is mainly as NO 3 N. The results also show that this method causes fewer disturbances to natural process and has no effect on the accumulative N's type of the process of mineralization. It is the effective method to determine the fluxes of the soil mineral N that under the field conditions.
【Fund】： 湖北省涝渍灾害与湿地农业重点实验室开放科研基金项目(HNKFJ2002A04);; 云南省自然科学基金项目(2001C0044M);; 云南省应用基础研究项目(2000FXZ02)资助~~
【CateGory Index】： S158.1
【CateGory Index】： S158.1