首页|期刊导航|中国农业科学(英文版)|Losses of Soil Organic Carbon and Nitrogen and Their Mechanisms in the Desertification Process of Sandy Farmlands in Horqin Sandy Land
中国农业科学(英文版)2003，Vol.2Issue(8)：890-897,8.
Losses of Soil Organic Carbon and Nitrogen and Their Mechanisms in the Desertification Process of Sandy Farmlands in Horqin Sandy Land
Losses of Soil Organic Carbon and Nitrogen and Their Mechanisms in the Desertification Process of Sandy Farmlands in Horqin Sandy Land
摘要
Abstract
Soil organic carbon (SOC) and total nitrogen (N) concentrations from bulk soils and soil particle size fractions in the different extent of desertified farmlands (potential, light, medium, severe, and most severe desertified farmlands) were examined to quantitatively elucidate losses of carbon and nitrogen and its mechanisms in the desertification process. Particle size fractions (2-0.1 mm, 0.1-0.05 mm, <0.05 mm) were obtained by granulometric wet sieving from 30 sandy soils (0-15cm depth) of different desertified extent. It was shown that soil physical stability index (St) in most severe desertified farmlands was 5-7% and St in other farmlands was less than 5%, which contributed to very low soil organic matter content. This was the intrinsic cause that sandy farmlands in Horqin sandy land was subject to risk of desertification. Desertification resulted in considerable losses of SOC and N. Regression analysis indicated that SOC and N content reduced 0.169 g kg-1 and 0.0215 g kg-1 respectively with one percent loss of soil silt and clay content. Losses of SOC and N were mostly the removal of fine particle size fractions (silt and clay, and a less extent very fine sand) from the farmlands by wind erosion, which were rich in organic matter and nutrients, as well as the depletion of organic C and N associated with coarse particles (>0.05 mm) in desertification process. The concentrations of C and N associated with sand (2-0.1 mm and 0.1-0.05 mm) significantly decreased with increase of desertified extent. Silt and clay associated C and N concentrations, however, were less changed, and in contrast, were higher in soils under most severe desertified extent than in soils under potential and severe desertified extent. The percentage of distribution in sand (>0.05 mm) associated C and N significantly increased with increase of desertified extent, suggesting that stability of SOC decreased in the desertification process.关键词
Farmland desertification/Soil organic carbon/Total nitrogen/Mechanisms of lossesKey words
Farmland desertification/Soil organic carbon/Total nitrogen/Mechanisms of losses分类
农业科技引用本文复制引用
SU Yong-zhong,ZHAO Ha-lin..Losses of Soil Organic Carbon and Nitrogen and Their Mechanisms in the Desertification Process of Sandy Farmlands in Horqin Sandy Land[J].中国农业科学(英文版),2003,2(8):890-897,8.基金项目
This study was sponsored by one of the China National Key Projects for Basic Scientific Research: The Bio-process of Desertification and the Mechanism of Recovering and Reconstructing of Vegetation (G2000048704). （G2000048704）
