Pedosphere 27(4): 725--736, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Effects of long-term fertilization on soil organic carbon and nitrogen in a highland agroecosystem
HAO Yajun1, WANG Yuhong2,3, CHANG Qingrui1 and WEI Xiaorong2,3
1College of Natural Resources and Environment, Northwest A&F University, Yangling 712100 (China)
2State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100 (China)
3Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100 (China)
ABSTRACT
      The effects of fertilization on the distributions of organic carbon (OC) and nitrogen (N) in soil aggregates and whether these effect vary with cropping system have not been well addressed. Such information is important for understanding the sequestration of OC and N in agricultural soils. In this study, the distributions of OC and N associated with soil aggregates were analyzed in different fertilization treatments in a continuous winter wheat cropping system and a legume-grain rotation system in a 27-year field experiment, to understand the effects of long-term fertilization on the distributions of OC and N in aggregates and to examine the recovery of soil OC and N in a highland agroecosystem. Manure fertilizer significantly decreased soil bulk density but increased the amount of coarse fractions and their associated OC and N stocks in the soils of both systems. Fertilizers N + phosphorus (P) and manure had similar effects on total soil OC and N stocks in both systems, but had larger effects on the OC and N stocks in > 2 mm aggregates in the legume-grain rotation system than in the continuous winter wheat system. The application of P increased the OC and N stocks in > 2 mm aggregates and decreased the loss of N from chemical fertilizers in the legume-grain rotation system. The results from this study suggested that P fertilizer should be applied for legume-included cropping systems and that manure combined with or without chemical fertilizers should be applied for semiarid cropping systems in order to enhance OC and N accumulation in soils.
Key Words:  chemical fertilizer, continuous winter wheat cropping, legume-grain rotation, manure, semiarid cropping system, soil aggregates
Citation: Hao, Y., Wang, Y., Chang, Q. and Wei, X. 2017. Effects of long-term fertilization on soil organic carbon and nitrogen in a highland agroecosystem. Pedosphere. 27(4): 725-736.
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