不同碳氮比油菜秸秆淹水还田腐解特征

The characteristics of returning straw to the field with different carbon-nitrogen ratios

由于农户施肥量差异较大,导致产生的秸秆养分含量尤其是秸秆碳氮比(C/N)不同,可能影响秸秆还田腐解。为探究不同C/N油菜秸秆腐解动态及养分释放特征,开展室内培养试验。试验选取C/N 92、C/N 116和C/N 136的油菜秸秆作为3个处理,采用尼龙网袋法淹水培养120 d。结果表明:不同C/N秸秆均表现为前期(0~10 d)迅速腐解(累积腐解率30.73%~33.59%)、中期(11~30 d)缓速腐解(累积腐解率5.10%~6.42%)、后期(31~120 d)慢速腐解(累积腐解率仅占总腐解率的4.50%)。不同C/N秸秆碳、氮、磷平均释放率分别为28.32%、46.28%、73.05%,元素释放率表现为磷>氮>碳。不同C/N秸秆养分释放差异表现在快速腐解期,其中C/N 92秸秆的氮素累积释放率相较于C/N 116和C/N 136分别高7.27%和15.16%,磷素释放率则表现为C/N 136秸秆较C/N 116和C/N 92分别高1.91%和13.53%,而不同C/N秸秆碳素在整个腐解期均无显著差异。综上所述,低C/N的油菜秸秆氮素具有更高的释放率,而高C/N秸秆磷素的释放率则高于低C/N的秸秆。

Due to large difference in the amount of fertilizer applied by farmers,the nutrient content of straw,especially the carbon-nitrogen ratio(C/N)of straw,may affect the straw returning to the field.In order to explore the decomposition dynamics and nutrient release characteristics of different C/N oilseed rape straw,an incubation experiment was carried out.In this experiment,three different C/N of oilseed rape straw treatments were set up,including C/N 92,C/N 116 and C/N 136,and the nylon net bag method was used to submerged-culture for 120 days.The results showed that the straw with different C/N showed rapid decay(30.73%~33.59%)in the early stage(0~10 d),slow decay(5.10%~6.42%)in the middle stage(11~30 d),and extremely slow decay(4.50%of the total decay)in the late stage(31~120 d).Under different C/N conditions,the average release rate of straw was 28.32%,the average release rate of nitrogen was 46.28%,and the average release rate of phosphorus was 73.05%.The release rate of carbon was slower than that of nitrogen and phosphorus,and the final release rate was phosphorus>nitrogen>carbon.Nutrient release of different C/N stalks was different in the rapid decomposition stage.The nitrogen cumulative release rate of C/N 92 stalks was 7.27%and 15.16%higher than that of C/N 116 and C/N 136,respectively,while the phosphorus release rate of C/N 136 stalks was 1.91%and 13.53%higher than that of C/N 116 and C/N 92 stalks,respectively.However,the carbon content of straw with different C/N had no significant difference during the whole decomposition period.In conclusion,the nitrogen release rate of oilseed rape straw with low C/N was higher,while the phosphorus release rate of oilseed rape straw with high C/N was higher than that of straw with low C/N.