有机培肥与耕作方式对稻麦轮作土壤团聚体和有机碳组分的影响

为了明确不同外源有机物和耕作方式对土壤地力培育的影响,以水稻-小麦轮作系统为对象,通过2个年度(2016—2018年)大田试验研究了外源有机物(秸秆和有机肥)和耕作方式及其交互作用稻麦秸秆还田配合旋耕(SR),稻麦秸秆还田配合翻耕(SP),秸秆不还田、增施有机肥配合旋耕(MR),秸秆不还田、增施有机肥配合翻耕(MP),秸秆不还田、不施用有机肥、旋耕深度15 cm(CKR)]对土壤团聚体和有机碳组成的短期影响。结果表明:SR处理能够降低水稻季土壤容重并增加总孔隙度。相比CKR,小麦季SR处理显著增加0.05mm水稳性团聚体含量,增加量为7.2%。此外,外源有机物和耕作对土壤有机碳活性组分具有显著影响。其中,易氧化有机碳(EOC)主要受耕作与有机物交互作用影响,酸水解有机碳(LPIc和LPII_c)主要受耕作措施的影响, SR处理的土壤EOC和LPI_c含量比CKR提高0.3～2.6 g·kg~(-1)。颗粒有机碳(POC)主要受外源有机物的影响,并且秸秆还田处理POC平均含量高于增施有机肥处理,增加量为0.75g·kg~(-1)。短期内,外源有机物和耕作及其交互作用对稳定性有机碳(黑碳和矿物结合态有机碳)的影响较小。综上,秸秆还田配合旋耕有助于提高土壤水稳性团聚体和活性有机碳的含量(EOC、LPI_c和POC)。

Effects of organic fertilization and tillage method on soil aggregates and organic carbon fractions in a wheat-rice system

In order to clarify the effect of different exogenous organic materials and tillage methods on soil fertility, with the rice and wheat rotation system as the study object, a two-year field experiment was conducted to study the short-term effects of different exogenous organic materials, tillage methods, and their interactions on soil aggregate and organic carbon composition. The results revealed that straw returning with rotary tillage method could decrease soil bulk density and increase total porosity. Compared with non-straw-returning treatment (CKR), the >0.05-mm water-stable aggregate content with straw-returning treatment under rotary tillage (SR) significantly increased (7.2%) in the wheat growing season. In addition, exogenous organic matter and tillage methods had significant effects on soil active organic carbon. Among them, easily oxidized organic carbon (EOC) was significantly affected by the interaction of exogenous organic materials and tillage method, and the acid-hydrolyzed organic carbon (LPI_c and LPII_c) was significantly affected by the tillage method. Compared with CKR treatment, the concentration of EOC and LPI_c with straw-returning treatment under rotary tillage increased by 0.3-2.6 g·kg^-1. The content of particulate organic carbon (POC) was significantly affected by exogenous organic materials, and the average POC content with straw-returning treatments was higher than that with organic fertilizer application treatments (increased by 0.75 g·kg^-1). In the short term, exogenous organic materials, tillage methods, and their interactions had negligible effect on the stability of organic carbon (black carbon and mineral-bonded organic carbon). In conclusion, straw returning combined with rotary tillage could improve the content of soil water-stable aggregates and active organic carbon (EOC, LPI_c, and POC).