双季稻-油菜耕作制对土壤肥力质量长期演变的影响

Impacts of long-term double-cropping rice-rape rotation on soil fertility quality

为了解长期双季稻-油菜耕作制下的土壤养分和肥力质量演变趋势,选取湖南省湘南毗邻的、连续耕作>30 a的稻-稻-油和稻-稻-闲(对照)水稻土为研究对象,对比分析了长期稻-稻-油和稻-稻-闲土壤不同土层、根际与非根际土壤pH、有机质、养分含量和肥力质量的差异。结果表明,与稻-稻-闲相比,长期稻-稻-油轮作土壤有机质含量显著下降了9%~11%,有效态Ca、Mg含量分别下降了10%~33%和14%~42%;相反,土壤全磷和有效磷含量分别提高了14%~56%和21%-46%,有效态Cu、Zn含量分别提高了20%~36%和7%~36%。主成分-聚类分析表明,长期稻-稻-油轮作土壤肥力质量等级(I-III)明显高于稻-稻-闲(III-VI),有助于提升水稻土养分有效性,改善肥力质量。但是,为弥补长期稻-稻-油轮作土壤有机质和Ca、Mg有效性的降低,有必要适当增施有机肥和石灰。

In order to understand the impacts of long-term double-rice cropping rotation on soil fertility quality,we selected adjacent paddy soils with more than 30 a double-cropping rice-rape(DRR)rotation,and double-cropping rice-fallow(DRF)rotation,DRF as a control in southern Hunan Province.We analyzed differences of soil pH,organic matter,nutrient content,and fertility quality among soil layers,or in rhizosphere and bulk soils between the two systems.Results showed that,compared with DRF,the content of soil organic matter,available Ca and Mg significantly decreased by 9%-11%,10%-33%,and 14%-42%in DRR,respectively,while the content of total P,available P,Cu and Zn increased by 14%-56%,21%-46%,20%-36%,and 7%-36%,respectively.Principal component-cluster analysis showed that the quality grade of soil fertility in DRR(Ⅰ-Ⅲ)was remarkably higher than that in DRF(Ⅲ-Ⅵ),indicating long-term DRR rotation would be good for enhancing paddy soil nutrient availability as well as improving soil fertility quality.However,it would be necessary to add organic fertilizer and lime appropriately to offsetting the reduction of soil organic matter and Ca and Mg availability in the long-term DRR rotation system.