Pedosphere 20(3): 285--292, 2010
ISSN 1002-0160/CN 32-1315/P
©2010 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Long-term effect of no-tillage on soil organic carbon fractions in a continuous maize cropping system of Northeast China |
HUANG Shan1, SUN Yan-Ni1, RUI Wen-Yi1, LIU Wu-Ren2 and ZHANG Wei-Jian 1,3 |
1 Institute of Applied Ecology, Nanjing Agricultural University, Nanjing 210095 (China);
2 Jilin Academy of Agricultural Sciences, Changchun 130124 (China);
3 Centre for Agroecology & Farming Systems, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081 (China) |
| ABSTRACT |
| Increasing evidence has shown that conservation tillage is an effective agricultural practice to increase carbon (C) sequestration in soils. In order to understand the mechanisms underlying the responses of soil organic carbon (SOC) to tillage regimes, physical fractionation techniques were employed to evaluate the effect of long-term no-tillage (NT) on soil aggregation and SOC fractions. Results showed that NT increased the concentration of total SOC by 18.1% compared with conventional tillage (CT) under a long-term maize (Zea mays L.) cropping system in Northeast China. The proportion of soil large macroaggregates (> 2000 μm) was higher in NT than that in CT, while small macroaggregates (250-2000 μm) showed an opposite trend. Therefore, the total proportion of macroaggregates (> 2000 and 250-2000 μm) was not affected by tillage management. However, C concentrations of macroaggregates on a whole soil basis were higher under NT relative to CT, indicating that both the amount of aggregation and aggregate turnover affected C stabilization. Carbon concentrations of intra-aggregate particulate organic matter associated with microaggregates (iPOM_m) and microaggregates occluded within macroaggregates (iPOM_mM) in NT were 1.6 and 1.8 times greater than those in CT, respectively. Carbon proportions of iPOM_m and iPOM_mM in the total SOC increased from 5.4% and 6.3% in CT to 7.2% and 9.7% in NT, respectively. Furthermore, the difference in the microaggregate protected C (i.e., iPOM_m and iPOM_mM) between NT and CT could explain 45.4% of the difference in the whole SOC. The above results indicate that NT stimulates C accumulation within microaggregates which then are further acted upon in the soil to form macroaggregates. The shift of SOC within microaggregates is beneficial for long-term C sequestration in soil. We also corroborate that the microaggregate protected C is useful as a pool for assessing the impact of tillage management on SOC storage. |
| Key Words: carbon sequestration, conservation tillage, particulate organic matter, physical fractionation, soil aggregates |
| Citation: Huang, S., Sun, Y. N., Rui, W. Y., Liu, W. R. and Zhang, W. J. 2010. Long-term effect of no-tillage on soil organic carbon fractions in a continuous maize cropping system of Northeast China. Pedosphere. 20(3): 285-292. |
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