不同作物秸秆在旱地和水田中的腐解特性及养分释放规律

以水稻、小麦、玉米秸秆和油菜、蚕豆青秆为研究对象,采用尼龙网袋法,研究了不同秸秆翻埋入旱地和水田后的腐解特性及养分释放规律,以期为紫色丘陵区农业秸秆循环利用和秸秆还田技术提供理论依据。结果表明:秸秆翻埋还田后,5种供试秸秆腐解速率均表现为前期(0~60 d)快、后期(60~360 d)慢。经过360 d的腐解,旱地秸秆累积腐解率为52.88%~75.80%,表现为油菜水稻玉米小麦蚕豆趋势,且蚕豆青秆累积腐解率显著低于其余秸秆;水田中秸秆累积腐解率为45.01%~62.12%,表现为水稻玉米小麦油菜蚕豆趋势。5种秸秆在旱地和水田中养分释放率均表现为钾磷氮碳,在试验终点,旱地中秸秆碳、氮、磷和钾释放率分别为65.50%~87.37%、54.64%~69.72%、89.65%~98.96%和79.92%~96.63%,且油菜秸秆养分释放率高于其他4种秸秆;水田中秸秆碳、氮、磷、钾释放率变幅分别为49.95%~69.57%、32.89%~77.11%、90.70%~96.80%、77.45%~90.47%。总体表现为秸秆在旱地土壤中的累积腐解率和养分释放率均大于水田,旱地油菜和水稻秸秆较易腐解,水田水稻和玉米秸秆较易腐解释;秸秆中钾素释放速率较高。

Nutrient release patterns and decomposition characteristics of different crop straws in drylands and paddy fields

To provide theoretical basis for crop straws recycling and straw use in agricultural fields, the characteristics of decomposition and release of nutrients of different crop strawsrice, wheat, corn, rapeseed (green stalk) and broad bean (green stalk)] were studied using the nylon net bag method in drylands and paddy fields. The results showed that the decomposition rate of straw was high at the early phase (0-60 d) which then dropped at the later phase (60-360 d). After 360 d, the cumulative decomposition rates of straw were 52.88%-75.80% and 45.01%-62.12% in drylands and paddy fields, respectively. The cumulative decomposition rate of broad bean was significantly lower than that of other crops in the two fields. Furthermore, rapeseed and rice decomposed faster in drylands and paddy fields. At the endpoint of the experiment, the sequence of nutrient release rate of straw in the two fields was K > P > N > C. The rate of carbon release by rice, corn, wheat, rapeseed and broad bean straws was up to 87.37% in dryland and 69.57% in paddy field. The rates of carbon release by rapeseed and rice were significantly higher than those of other crop straws in dryland and paddy field. The average rate of nitrogen release by the five straws tracked the following trend:broad bean (69.72%) > rice (68.45%) > rapeseed (63.60%) > corn (57.28%) > wheat (54.64%) in dryland. The rate of nitrogen release by broad bean was the highest (77.11%) in the paddy field. The rates of release of phosphorus by straw were 89.65%-98.96% and 90.70%-96.80% in dryland and paddy field, respectively. Then the rate of release of phosphorus by wheat was persistently lower than that of any other straw in both fields. The rate of release of potassium by rapeseed was respectively 20.91%, 5.84%, 6.67% and 5.19% higher than that of wheat, rice, corn and broad bean in dryland. Also the rate of release of potassium by wheat was significantly lower than the others. Overall, the decomposition and nutrient release rates in dryland were higher than those in paddy field. Rapeseed green straw in dryland, and rice and maize straws in paddy field were more easily decomposed than other crops straws. The release rate of potassium was highest in all the tested elements.