Effects of long-term conventional cultivation on stability and distributions of organic carbon in soil aggregates
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DOI:10.7606/j.issn.1000-7601.2012.06.25
Key Words: aggregate  organic carbon  conventional cultivation
Author NameAffiliation
ZHOU Zhenfang Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University, Lanzhou 730000, China 
HU Yajie Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University, Lanzhou 730000, China 
MACan Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University, Lanzhou 730000, China 
XUE Tianzhu Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University, Lanzhou 730000, China 
GUO Ying Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University, Lanzhou 730000, China 
WEI Guoxiao Key Laboratory of Western China’s Environmental Systems, Ministry of Education, Lanzhou University, Lanzhou 730000, China 
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Abstract:
      Organic matters improve the physical, chemical and biological properties of soil, influence soil structure by binding mineral particles, while cultivation is an important factor influencing the content of soil organic matters. Also soil aggregates are important indicators of soil physical quality, reflecting the impact of land use and management. This study, by selecting five sampling plots with different cultivation age, was conducted to exmine the effects of conventional cultivation on soil organic carbon and aggregates in the semiarid Loess Plateau in China. The results showed that the content of water-stable macroaggregates(≥0.25mm) decreased by 40.5% and 12.5% in the layers of 0~20 cm and 0~40 cm after>70 years reclamation, respectively. Aggregates could be broken typically by reclamation. The average val-ues of MWD and GMD in 0~20 cm were nearly 10% higher than in 20~40 cm layer, and the difference decreased with cultivation time. Organic carbon contents of >2 mm and 0.25~0.106 mm water-stable aggregates were much higher in 0~20 cm layer, while it was not obvious in 20∽40 cm layer, carbon contents of water-stable aggregates for the whole soil profiles decreased generally with cultivation time. The favorable correlation of MWD and GMD with organic carbon in soil aggregates indicated that aggregates could protect soil organic carbon from erosion.