Decomposition characteristics of rapeseed and wheat straws under different rice cultivations and straw mulching models | 不同水稻栽培模式和秸秆还田方式下的油菜、小麦秸秆腐解特征

Chino. 目的于2007―2008连续2年在不同水稻栽培模式和秸秆还田方式下，研究油菜、小麦秸秆腐解特征及养分释放规律。方法在水稻常规栽培和节水灌溉栽培模式下，采用尼龙网袋研究法。将装满秸杆的网袋放在水稻田表层和埋入土中，模拟秸秆覆盖还田和土埋还田。结果秸秆还田后，在0－30 d腐解较快，后期腐解速率逐渐变慢。油菜秸秆在水稻节水栽培模式下，采用土埋还田腐解率最大，90 d时腐解率达61.06%。试验结束时，小麦秸秆累计腐解率为48.88%－59.95%，油菜秸秆为50.88%－61.06%。常规栽培模式下，秸秆覆盖还田腐解率＞秸秆土埋；节水栽培模式下，秸秆土埋＞秸秆覆盖。秸秆覆盖还田时，两种栽培模式秸秆腐解率差异不大。而在秸秆土埋还田时，节水栽培秸秆腐解率＞常规栽培。秸秆中养分释放速率表现为钾＞磷＞氮≈碳；90 d时，小麦秸秆中48.29%－63.79%的碳、48.35%－52.83%的氮、54.83%－67.49%的磷和91.98%－95.99%的钾被释放；油菜秸秆中50.29%－66.55%的碳、46.48%－57.67%的氮、56.44%－75.64%的磷和92.31%－96.24%的钾被释放。栽培模式和还田方式对秸秆碳、氮和磷释放率的影响与对秸秆腐解率的影响规律基本一致。腐解30 d时，秸秆中已有超过90%的钾被释放出来。结论实行秸秆还田，水稻栽培模式宜采用节水灌溉栽培，可以促进秸秆腐解，提高其养分释放率。

Inglés. ObjectiveThe decomposition characteristics and nutrient releasing patterns of rapeseed and wheat straws were studied under different rice cultivations and straw mulching models in 2007 and 2008 growing seasons, respectively.MethodWheat and rapeseed straws were wrapped in net nylon bags and put on the surface or embedded into the soil under conventional cultivation and water-saving cultivation models.ResultThe results showed that the decomposition rate of straw was faster in the first 30 days and then slowed down until the end of the experiment. Under water-saving cultivation model, 90 days after straws were embedded into soil, the decomposition rate was high up to 61.06%. The cumulative decomposition rates of wheat and rapeseed straw were 48.88%-59.95% and 50.88%-61.06%, respectively. Under conventional cultivation model, the straws that were mulched decomposed faster than the straws that were embedded into the soil did. With straw mulching, there was no obvious difference in decomposition rates between the two cultivation models. When straws were embedded into the soil, the straw under water-saving cultivation model decomposed faster than the straw under the conventional cultivation model. The sequence of nutrients releasing rates were K＞P＞N≈C. C releasing rates of wheat straw and rapeseed straw were up to 48.29-63.79% and 50.29-66.55%, and N were up to 48.35-52.83% and 46.48%-57.67%, and P were up to 54.83%-67.49% and 56.44%-75.64%, and K were up to 91.98%-95.99% and 92.31%-96.24% after 90 days of decomposition, respectively. The effect of cultivation model and incorporation method on N, P and C releasing patterns had almost the same trend with the decomposition of straw. K release rate was more than 90% after 30 days of decomposition. Conclusion It is concluded that on the basis of straw mulching, the water-saving cultivation model can promote the straw to decompose and to release the nutrients.