Changes in aggregate-associated organic carbon and nitrogen after 27 years of fertilization in a dryland alfalfa grassland on the Loess Plateau of China  

作　　者：ZHANG Liqiong WEI Xiaorong HAO Mingde ZHANG Meng 

机构地区：[1]College of Natural Resources and Environment, Northwest A&F University [2]College of Agriculture and Life Sciences, Ankang University [3]State Key Laboratory of Soil Erosion and Dryland Farming in the Loess Plateau, Northwest A&F University

出　　处：《Journal of Arid Land》2015年第4期429-437,共9页干旱区科学（英文版）

基　　金：funded by the Program for New Century Excellent Talents in University (NCET-13-0487);the Program from Northwest A&F University (2014YQ007);the National Basic Research Program of China (2009CB118604);the National Science and Technology Support for Major Projects of China (2011BAD31B01);the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-JC408);Science and Technology Generalized Program for the Overall Development of Agriculture in Ningxia (NTKJ-2014-01);the Scientific Research Program from Education Department of Shaanxi Province (11JK0650).

摘　　要：Changes in the distribution of soil aggregate sizes and concentrations of aggregate-associated organic carbon （OC） and nitrogen （N） in response to the fertilization of grasslands are not well understood. Understanding these changes is essential to the sustainable development of artificial grasslands. For understanding these changes, we collected soil samples at 0-20 and 20-40 cm depths from a semi-arid artificial alfalfa grassland after 27 years of applications of phosphorus （P） and nitrogen＋phosphorus＋manure （NPM） fertilizers on the Loess Pla- teau of China. The distribution of aggregate sizes and the concentrations and stocks of OC and N in total soils were determined. The results showed that NPM treatment significantly increased the proportions of 〉2.0 mm and 2.0-0.25 mm size fractions, the mean geometric diameter （MGD） and the mean weight diameter （MWD） in the 0-20 cm layer. Phosphorous fertilizer significantly increased the proportion of 〉2.0 mm size fractions, the MGD and the MWD in the 0-20 cm layer. Long-term application of fertilization （P and NPM） resulted in the accumulation of OC and N in soil aggregates. The largest changes in aggregate-associated OC and N in the 0-20 cm layer were found at the NPM treatment, whereas the largest changes in the 20-40 cm layer were found at the P treatment. The results suggest that long-term fertilization in the grassland leads to the accumulation of OC and N in the coarse size fractions and the redistribution of OC and N from fine size fractions to coarse size fractions.Changes in the distribution of soil aggregate sizes and concentrations of aggregate-associated organic carbon （OC） and nitrogen （N） in response to the fertilization of grasslands are not well understood. Understanding these changes is essential to the sustainable development of artificial grasslands. For understanding these changes, we collected soil samples at 0-20 and 20-40 cm depths from a semi-arid artificial alfalfa grassland after 27 years of applications of phosphorus （P） and nitrogen＋phosphorus＋manure （NPM） fertilizers on the Loess Pla- teau of China. The distribution of aggregate sizes and the concentrations and stocks of OC and N in total soils were determined. The results showed that NPM treatment significantly increased the proportions of 〉2.0 mm and 2.0-0.25 mm size fractions, the mean geometric diameter （MGD） and the mean weight diameter （MWD） in the 0-20 cm layer. Phosphorous fertilizer significantly increased the proportion of 〉2.0 mm size fractions, the MGD and the MWD in the 0-20 cm layer. Long-term application of fertilization （P and NPM） resulted in the accumulation of OC and N in soil aggregates. The largest changes in aggregate-associated OC and N in the 0-20 cm layer were found at the NPM treatment, whereas the largest changes in the 20-40 cm layer were found at the P treatment. The results suggest that long-term fertilization in the grassland leads to the accumulation of OC and N in the coarse size fractions and the redistribution of OC and N from fine size fractions to coarse size fractions.

关 键 词：alfalfa grassland long-term fertilization nitrogen organic carbon semi-arid Loess Plateau 

分 类 号：S812.4[农业科学—草业科学]