不同粉碎程度对绿肥籽粒苋腐解过程中氮、钾释放与转化的影响

Release and Transformation of Nitrogen and Potassium during the Decomposition of Amaranthus hypochondriacus with Different Grinding Degrees

采用原位室内培养的方法,研究绿肥籽粒苋腐解过程中氮、钾释放规律,并分析不同粉碎程度对籽粒苋腐解过程中氮、钾释放的影响。结果表明,籽粒苋还田腐解前15 d,是氮、钾的快速释放期;经过34 d腐解,籽粒苋茎秆氮、钾的养分累积释放率分别达到72.8%和94.2%,其中籽粒苋释放的氮素对土壤无机氮的最大表观贡献率为12.0%,钾素对土壤有效钾的最大表观贡献率为69.8%。不同粉碎程度处理的籽粒苋茎秆还田后,土壤中氮、钾含量变化有差异,土壤铵态氮含量和速效钾含量为T3(添加粒径为5 cm±0.5 cm的籽粒苋茎秆)> T2(添加粒径为3 cm±0.5 cm的籽粒苋茎秆)> T1(添加粒径<2 mm的籽粒苋茎秆),土壤无机氮含量为T1> T2> T3,土壤缓效钾含量处理间无显著差异。由此表明,籽粒苋腐解释放的氮素对土壤无机氮的表观贡献率远小于钾素对土壤有效钾的表观贡献率,籽粒苋粉碎程度越细越有利于土壤无机氮含量的提升,而粉碎程度越粗越利于土壤速效钾含量的提升。

In-situ incubation experiment was used to explore the release dynamics of nitrogen(N)and potassium(K)during the decomposition of Amaranthus hypochondriacus stalk with different sizes.The results showed that the N and K of Amaranthus hypochondriacus stalk were rapidly released in the 15 days after its returning to soil.After 34 days,the release rates of N and K from Amaranthus hypochondriacus stalk reached to 72.8%and 94.2%,respectively.The maximum apparent contribution rate of N from Amaranthus hypochondriacus to mineral N(Nmin)in soil was only12%,while that of K to available K was 69.8%.The changes of N and K in soil were different among varied sizes of Amaranthus hypochondriacus stalk.The contents of NH4+-N and rapidly available K in soil were decreased following the order of T3(5 cm±0.5 cm of Amaranthus hypochondriacus stalk)>T2(3 cm±0.5 cm of Amaranthus hypochondriacus stalk)>T1(<2 mm of Amaranthus hypochondriacus stalk).The contents of Nmin in soil were T1>T2>T3,and the slowly available K in soil had no distinction in the treatments.The apparent contribution rate of N in Amaranthus hypochondriacus to Nmin in soil was far less than that of K to available K.The bigger size of Amaranthus hypochondriacus stalk was better for increasing soil Nmin,while the smaller size of Amaranthus hypochondriacus stalk was better for increasing soil rapidly available K.