柑橘大豆间作对土壤团聚体结构及其有机碳、氮分布的影响

Effects of Citrus and Soybean Intercropping on Soil Aggregate Structure,Organic Carbon and Nitrogen Distribution

探讨柑橘大豆不同间作年限下土壤团聚体结构及有机碳、氮分布差异,旨在为果园土壤改良提供参考。通过田间定位试验设置清耕区(CK)、柑橘间作大豆1年(T1)、柑橘间作大豆2年(T2)和柑橘间作大豆3年(T3)4个处理,测定土壤团聚体组成、稳定性、有机碳和全氮等指标。结果表明:①与清耕柑橘园相比,柑橘间作大豆的土壤>0.25 mm大团聚体含量提高了19.58%~22.29%;②柑橘间作大豆的土壤团聚体稳定性特征表现为:T3>T2>T1>CK;③团聚体粒径中的有机碳和全氮含量表现为>5 mm粒径最高,<0.25 mm粒径含量最低,柑橘间作大豆的土壤C/N值较清耕区提高了1.16倍~1.19倍;④土壤团聚体组成与团聚体有机碳和全氮含量的相关性显著,RDA分别解释99.32%和94.99%的差异信息,其中>5、5~2和0.5~0.25 mm粒径土壤团聚体是影响土壤有机碳和全氮含量变化的主要环境因子。总体而言,柑橘园行间间作大豆可增加土壤肥力,改善土壤团聚体结构,是一种可持续农业发展模式。

The study aimed to investigate the differences in soil aggregate structures and organic carbon and nitrogen distribution under different years of citrus and soybean intercropping system in order to provide reference for orchard soil improvement.Four treatments were set up in the field positioning experiments,including clear tillage area(CK,citrus without soybean),citrus and soybean intercropping for 1 year(T1),2 years(T2)and 3 years(T3),respectively,and then soil aggregate composition,stability,organic carbon and total nitrogen contents were determined and compared under the different treatments.The results showed that:1)Compared with CK,the contents of large aggregates>0.25 mm increased by 19.58%to 22.29%under citrus and soybean intercropping treatments.2)The stability characteristics of soil aggregates in citrus and soybean intercropping were as follows:T3>T2>T1>CK.3)The contents of organic carbon and total nitrogen were the highest in>5 mm aggregates,but the lowest in<0.25 mm aggregates,and the C/N ratios under citrus and soybean intercropping treatments increased by 1.16–1.19 times compared with CK.4)The correlations were significant between soil aggregate composition and organic carbon and total nitrogen contents in soil aggregates.RDA explained 99.32%and 94.99%of difference information respectively,among which>5,5–2 and 0.5–0.25 mm soil aggregates were the main environmental factors affecting the changes of soil organic carbon and total nitrogen contents.In conclusion,citrus and soybean intercropping system promotes soil fertility and soil aggregate structure,thus,it is a sustainable agricultural mode.