ABSTRACT

We studied the effects of tillage, crop residues, and green manure on soil carbon pools and hydrolytic enzyme activity in a sandy loam after five cycles of the rice-wheat system (RWS). Four main plot treatments in rice were combinations of wheat straw and Sesbania green manure (GM) management: (1) puddled transplanted rice (PTR) with no wheat straw, (2) PTR with 25% wheat stubbles (12–15 cm long) retained, (3) PTR with no wheat straw plus GM, and (4) PTR with 25% wheat stubbles plus GM. Three subplots treatments in subsequent wheat were (1) conventional tillage with rice straw removed, (2) zero tillage (ZT) with rice straw removed, and (3) ZT with 100% rice straw retained as a surface mulch. The results showed that PTR with wheat stubbles retained plus GM and ZT wheat with rice straw retained (ZTW_RS100) significantly (p< 0.05) increased all the carbon pools and hydrolytic enzymes except phenol oxidase and peroxidase activities. The carbon management index under ZTW_RS100 retained was significantly higher than zero-till or conventional till wheat without residue. The principal component analysis identified active carbon, less labile carbon pools; xylanase and dehydrogenase hydrolytic enzymes as the most reliable sensitive indicators for assessing soil quality for conservation agriculture (CA) – based practices in RWS. The study showed that adoption of PTR with 25%-anchored wheat stubbles retained plus GM in rice followed by ZTW_RS100 in wheat was the best crop production strategy for enhanced carbon pools, hydrolytic enzymatic activities and gives an idea of its overall fitness for carrying out ecosystem functions.

摘要

我们研究了稻麦系统（RWS）的五个循环后，耕作，农作物残留物和绿肥对沙壤土中碳库和水解酶活性的影响。水稻的四个主要地块处理方法是小麦秸秆和塞斯巴尼亚绿肥（GM）的组合管理：（1）不带麦秸秆的混水水稻（PTR），（2）小麦秸秆含量为25％（12-15厘米长）的PTR保留，（3）没有麦杆加GM的PTR，和（4）25％麦茬加GM的PTR。在随后的小麦中进行三个子图处理：（1）除去稻草的常规耕作；（2）除去稻草的零耕作（ZT）；（3）保留100％稻草作为表层覆盖物的ZT。结果表明，保留有麦茬的PTR以及保留有稻草的GM和ZT小麦（ZTW _RS100）（p <0.05）显着增加了除酚氧化酶和过氧化物酶活性以外的所有碳库和水解酶。ZTW _RS100保留的碳管理指数显着高于零耕或常规耕作小麦，无残留。主成分分析确定了活性炭，不稳定的碳库；木聚糖酶和脱氢酶水解酶是评估RWS中基于保护性农业（CA）的土壤质量的最可靠的敏感指标。研究表明，采用保留25％锚定麦茬的PTR和水稻中的GM以及ZTW _RS100 小麦是增强碳库，水解酶活性的最佳作物生产策略，并提出了其整体适合执行生态系统功能的想法。