• ISSN 1008-505X
  • CN 11-3996/S
张肖林, 李勇, 于寒青, 刘文祥. 黄土区退耕草地合理放牧可减少土壤CO2排放和土壤侵蚀[J]. 植物营养与肥料学报, 2016, 22(4): 988-997. DOI: 10.11674/zwyf.15462
引用本文: 张肖林, 李勇, 于寒青, 刘文祥. 黄土区退耕草地合理放牧可减少土壤CO2排放和土壤侵蚀[J]. 植物营养与肥料学报, 2016, 22(4): 988-997. DOI: 10.11674/zwyf.15462
ZHANG Xiao-lin, LI Yong, YU Han-qing, LIU Wen-xiang. Reasonable grazing on grain for green grassland on Loess Plateau can reduce soil CO2 emission and soil erosion[J]. Journal of Plant Nutrition and Fertilizers, 2016, 22(4): 988-997. DOI: 10.11674/zwyf.15462
Citation: ZHANG Xiao-lin, LI Yong, YU Han-qing, LIU Wen-xiang. Reasonable grazing on grain for green grassland on Loess Plateau can reduce soil CO2 emission and soil erosion[J]. Journal of Plant Nutrition and Fertilizers, 2016, 22(4): 988-997. DOI: 10.11674/zwyf.15462

黄土区退耕草地合理放牧可减少土壤CO2排放和土壤侵蚀

Reasonable grazing on grain for green grassland on Loess Plateau can reduce soil CO2 emission and soil erosion

  • 摘要: 【目的】在退耕草地实施合理放牧,有助于减少土壤CO2排放、 减缓土壤侵蚀。为验证此假设,本研究选择黄土高原渭北旱原坡地,建立退耕草地放牧、 退耕草地不放牧和传统农业耕作三种处理的对比试验小区,定量研究了退耕草地合理放牧相对于退耕草地在减少土壤CO2排放和土壤侵蚀的作用及其影响因素,为探寻在我国西部退耕还草区实施畜牧业生产与环境保护的协调发展模式提供科学依据。【方法】在建立的退耕草地放牧、 退耕草地不放牧和传统农业耕作3种处理的试验小区,利用LI-8100 碳通量自动测量仪原位监测植物生长期(4~8月)和放牧前后土壤CO2排放速率的变化,同时利用时域反射仪(TDR)测定表层0—10 cm土壤含水量,用地温表测定土壤表层2 cm和5 cm的温度。利用环境放射性核素 7Be示踪技术监测较大降雨事件引起的土壤侵蚀速率,同时取样测定侵蚀区土壤有机碳含量,比较不同处理小区侵蚀导致的土壤有机碳流失量。【结果】观测期间,3种处理CO2平均排放速率大小顺序为退耕草地3.69±0.39 μmol/(m2·s)退耕草地放牧3.00±0.44 μmol/(m2·s)传统农耕地1.99±0.22 μmol/(m2·s),坡耕地退耕还草后土壤CO2排放增加了85%,而合理放牧使退耕草地土壤CO2排放量减少了19%。放牧后退耕草地土壤CO2排放速率平均减少了11%,减少值在2% ~ 41%之间。观测期内,退耕草地放牧后土壤侵蚀速率比农耕地和退耕草地分别减少了93% 和77%。坡耕地退耕还草后土壤CO2排放增加主要由于草被植物引起土壤有机碳储量增加和土壤侵蚀强度减小,放牧后退耕草地土壤CO2排放减少主要与动物踩踏引起土壤容重明显增加及草类植被地上部分向土壤中输入的有机碳的减少有关。水分、 温度影响因子无法解释3种处理间土壤CO2排放差异。【结论】合理放牧不仅能显著减少退耕草地土壤CO2排放,而且可以有效控制退耕草地土壤和有机碳侵蚀流失。放牧期间动物的踩踏作用引起草地土壤容重显著增加是退耕草地土壤CO2排放量和土壤侵蚀速率减少的主要原因。本研究结果揭示,在我国黄土高原和类似的退耕还草地区实施合理放牧既可以促进当地畜牧业生产,又能控制土壤侵蚀和减少CO2的排放,是一种值得探究的草地可持续发展管理模式。

     

    Abstract: 【Objectives】 Reasonable grazing on grain for green grassland is considered helpful for reducing soil CO2 emissions as well as soil erosion. In order to verify this hypothesis, we set up three treatments at our study site-a slope on the Weibei Loess plateau-in order to investigate the effect of reasonable grazing on soil CO2 emissions and soil erosion. Additionally, we hope this study can provide a scientific basis for the coordinated development of livestock production and environmental protection in Chinese western grain for green grassland. 【Methods】 The three treatments used in our study were 1) grain for green grassland with grazing (G+G), 2) grain for green grassland without grazing (G-G) and 3) conventional tillage (CT). Soil CO2 emission rates were automatically monitored by a LI-8100 carbon flux measuring instrument in situ, with soil moisture content measured by TDR and soil temperature measured by a thermometer. The environmental radioactive nuclide,7Be, was used as a tracer for the soil erosion rate following heavy rainfall. 【Results】 During the test period, average CO2 emission rates of these 3 test plots were as follows: G-G 3.69± 0.39 μmol/(m2·s)G+G 3.00± 0.44 μmol/(m2·s)CT 1.99± 0.22 μmol/(m2·s). Soil CO2 emission in G-G was 85% more than CT, whilst soil CO2 emission rate in G+G was 23% less than G-G. Grazing activity was found to significantly reduce soil CO2 emission rates in G+G by 2%-41%, with the average of 11%. During the observation period, the soil erosion rate in the G+G plot was significantly less than that observed in both CT and G-G, by 93% and 77%, respectively. Compared to CT, the increased soil CO2 emissions observed in G-G was due to increased SOC, whilst for G+G this was due to decreased soil erosion. Trampled ground as a result of animal grazing led to a significant increase in soil bulk density with a concomitant reduction in the amount of organic carbon entering the soil. Both of these factors led to the reduction of soil CO2 emissions in G+G. However, the difference of soil CO2 emissions among these three plots could not be explained by soil moisture and temperature. 【Conclusions】 Our study found that reasonable grazing activity would not only decrease the soil CO2 emissions, but also could effectively control soil erosion and SOC loss, which would in turn facilitate the increase of the soil carbon reserve. Trampled ground from animal grazing can lead to an increase in soil bulk density, a major contributing factor for the reduction in soil CO2 emissions and soil erosion rates. Our research revealed that in the Chinese Loess plateau or similar grain for green region, reasonable grazing can not only promote the local livestock production, but also help control soil erosion and reduce CO2 emissions. Thus this has been a worthwhile study for investigating various models of sustainable development for grassland management.

     

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