不同作物还田秸秆的养分释放特征试验

为了探索秸秆还田与化肥的合理搭配施用，采用尼龙网袋法，研究了水稻秸秆、小麦秸秆、油菜秸秆在淹水培养下养分释放特征。结果表明，供试秸秆腐解速率均表现在培养前期腐解较快，不同秸秆之间表现为油菜秸秆大于水稻秸秆和小麦秸秆；后期腐解速率逐渐变慢，3种秸秆之间差异不明显。经过124 d的培养，水稻秸秆、小麦秸秆、油菜秸秆的累积腐解率分别为49.17%、52.17%和49.81%。秸秆中养分释放速率均表现为K＞P＞C＞N，释放量表现为C＞K＞N＞P。经过124 d的腐解，水稻秸秆、小麦秸秆、油菜秸秆的碳释放率分别为7.53%、66.58%、52.54%；氮分别为42.05%、49.26%、57.83%；磷分别为68.28%、59.93%、67.32%；钾在培养12 d后释放率均达到98%。根据秸秆腐解特征及养分含量，作物推荐施肥量中可以减少钾肥用量，并适当延后施用；在还田初期可以不调整氮磷肥的施用量。

Nutrient release characteristic of different crop straws manure

In order to find out the proper proportions of crop straws and chemical fertilizer used in field, characteristic of nutrients release of rice straw, wheat straw and rapeseed straw were studied by method of nylon net bag under waterlogged incubation. The results showed that the decomposition rate of crop straws was much faster at the beginning stage and rapeseed straw decomposed faster than rice straw and wheat straw. And crop straws decomposition rate kept a slowly steady until the end of experiment, which had no obvious difference among three crop straws. After 124 days incubation, the cumulative decomposition rates of rice straw, wheat straw and rapeseed straw were 49.17%, 52.17% and 49.8%, respectively. The sequence of nutrients release rates of the three crop straws were K>P>C>N, while the sequence of nutrients release amount were C>K>N>P. C release rate of rice, wheat and rapeseed straw were up to 57.53, 66.58 and 52.54 percent, and N were up to 42.05, 49.26 and 57.83 percent, and P were up to 68.28, 59.93 and 67.32 percent after 124 days incubation, respectively. For all three crop straws K release rate was 98 percent within the first 12 days of incubation. It was indicated that on the basis of crop straws decomposition characteristics and nutrients release amount the application rates of K fertilizer should be decrease and used in crop growth later stage, while N and P should be maintained as usual practice at early crop growth stage.