冬季覆盖作物残茬还田对双季稻田土壤有机碳和碳库管理指数的影响

Effects of winter cover crop straw recycling on soil organic carbon and soil carbon pool management index in paddy fields

研究冬季不同覆盖作物残茬还田后稻田土壤总有机碳、活性有机碳含量和碳库管理指数的变化,对合理利用冬闲稻田,发展冬季覆盖作物,以及科学评价不同种植模式具有重要意义。本研究以不同冬季覆盖作物–双季稻定位试验为研究对象,采用田间小区试验方法,分析了黑麦草–双季稻(T1)、紫云英–双季稻(T2)和油菜–双季稻(T3)3种种植模式不同冬季覆盖作物残茬还田后对土壤耕层(0～20 cm)总有机碳、活性有机碳含量的影响,并计算了各处理的碳库活度、碳库活度指数、碳库指数和碳库管理指数。结果表明,与冬闲–双季稻(对照)相比,T1、T2和T3处理的冬季覆盖作物残茬还田均提高了稻田土壤总有机碳和活性有机碳含量,其大小顺序均表现为T2>T1>T3>CK。其中,各处理稻田土壤总有机碳含量均显著高于对照,早稻收获时T1、T2和T3处理土壤总有机碳含量两年平均分别比对照增加6.73%、10.53%和4.79%,晚稻收获时两年平均分别增加4.16%、6.20%和2.37%;T1和T2处理土壤活性有机碳含量均显著高于对照,早稻收获时两年平均分别比对照增加10.52%和21.52%,晚稻收获时两年平均分别增加11.99%和15.59%。冬季覆盖作物残茬还田提高了土壤碳库活度、碳库活度指数、碳库指数和土壤碳库管理指数,其大小顺序均表现为T2>T1>T3。总的来说,各处理中以紫云英残茬还田的效果为最好,黑麦草和油菜残茬还田的效果次之。

Research on total organic carbon （TOC）, carbon pool activivty （CPA） and carbon pool management index （CPMI） of paddy fields with different double cropping rice patterns could enhance the exploitation of winter cover crop and the assessment of paddy rice cropping patterns. This paper discussed soil TOC, CPA and CPMI in double cropping rice systems with straw recycling of different winter cover crops. Experiments were conducted in field plot trials of ryegrass and double cropping rice （T1）, Chinese milk vetch and double cropping rice （T2）, rape and double cropping rice （T3） and fallow and double cropping rice （CK）. The results showed that recycling of winter cover crop straws significantly increased soil TOC and CPA over CK. The order of TOC content and CPA under different cropping patterns was T2 〉 T1 〉 T3 〉 CK at the early and later rice harvest stages. Compared with CK, T1, T2 and T3 averagely increased soil TOC content respectively by 6.73%, 10.53% and 4.79% at early rice harvest in 2011 and 2012 and by 4.16%, 6.20% and 2.37% at later rice harvest in 2011 and 2012. However, no significant difference existed in TOC content among T1, T2 and T3 treatments. The CPA under treatments T1 and T2 with winter cover crop straw recycling was also higher than that of CK. Compared with CK, CPA under treatments T1 and T2 on average increased respectively by 10.52% and 21.52% at early rice harvest and by 11.99% and 15.59% at later rice harvest in 2011 and 2012. Also compared with CK, CPA, activity index （AI）, carbon pool index （CPI） and CPMI under treatments T1, T2 and T3 improved at early and later rice harvest stages. The results further showed that CPA, AI, CPI and CPMI increased with winter cover crop straw recycling. The order of CPA, AI, CPI and CPMI under the different cropping patterns were T2 〉 T1 〉 T3 〉 CK. Thus winter cover crop straw recycling significantly influenced TOC content, AC and CPMI in paddy fields. Winter cover crop straw recycling had the best effect with Chinese milk vetch, followed by ryegrass and then rape.