Wu Jia-Mei, Ji Xiong-Hui, Peng Hua, Shi Li-Hong, Liu Zhao-Bing, Tian Fa-Xiang, Huo Lian-Jie, Zhu Jian
Institute of Soil and Fertilizer, Hunan Academy of Agricultural Sciences, Changsha 410125, China.
Ying Yong Sheng Tai Xue Bao. 2011 Dec;22(12):3196-202.
In a long-term site-specific experiment with rice straw return (RSR) and in a short-term experiment with different RSR modes, this paper studied the effects of RSR on the soil organic carbon (SOC) sequestration, methane emission, and net carbon sink in a double season paddy field. RSR increased the SOC content, and the annual increasing rate of soil carbon sink in plow layer (0-15 cm) under long-term RSR was 0.07 t C x hm(-2) x a(-1). With the increasing amount of RSR, the apparent SOC transformation rate decreased. RSR promoted the methane emission from the paddy field significantly, and the methane emission flux in treatment RSR plus NPK during early- and late rice growth seasons increased by 75.0% and 251.5% (P < 0.01), respectively, compared with that in treatment NPK. The methane emission increased with the increasing amount of RSR. Under the similar tillage mode and rice yield, the rice straw returned had the similar apparent methane transformation rate. Considering the soil carbon sequestration and the net carbon sink after methane emission in the paddy field comprehensively, treatment RSR plus NPK had significant negative effect on the carbon sink which was basically approached to the bio-fixation of carbon by rice and increased by 158.3%, as compared with treatment NPK. Among different RSR modes, rice straw mulching plus no tillage decreased soil methane emission significantly, with the net carbon sink decreased by 50.9% as compared with the treatment high stubble plus tillage, and benefited the high and stable yielding of rice.
通过一项长期的稻草还田（RSR）定位试验以及一项不同RSR模式的短期试验，本文研究了稻草还田对双季稻田土壤有机碳（SOC）固存、甲烷排放及净碳汇的影响。稻草还田增加了SOC含量，长期稻草还田条件下耕层（0 - 15厘米）土壤碳汇的年增加速率为0.07 t C x hm(-2) x a(-1)。随着稻草还田量的增加，表观SOC转化率降低。稻草还田显著促进了稻田甲烷排放，与NPK处理相比，早稻和晚稻生长季RSR + NPK处理的甲烷排放通量分别增加了75.0%和251.5%（P < 0.01）。甲烷排放随稻草还田量的增加而增加。在相似的耕作模式和水稻产量下，稻草还田具有相似的表观甲烷转化率。综合考虑稻田土壤碳固存及甲烷排放后的净碳汇，RSR + NPK处理对碳汇有显著负面影响，与NPK处理相比，其净碳汇基本接近水稻生物固碳量，且增加了158.3%。在不同的稻草还田模式中，稻草覆盖免耕显著降低了土壤甲烷排放，与高留茬翻耕处理相比，净碳汇降低了50.9%，且有利于水稻高产稳产。
