Objective The effects of different organic materials on aggregate stability and aggregate organic carbon were studied in order to provide a basis for improving the structure of yellow soil in Guizhou Province.

Method Taking yellow soil dryland as the research object, maize as the tested crop, adopting the random block design, four treatments including conventional chemical fertilizer (CK) , husks + rapeseed cake + charcoal + N fertilizer reduction (BC) , husks + rapeseed cake + N fertilizer reduction (RS) , N fertilizer reduction (DP) were applied, maize yield and soil organic carbon (SOC) were measured at harvest stage, and mean weight diameter (MWD) , geometric mean diameter (GMD) , and aggregate content > 0.25 mm (R_0.25) were used to evaluate aggregate stability.

Result The addition of organic materials promoted the formation of large macroaggregates (8 ~ 2mm) and decreased the content of microaggregates (0.25 ~ 0.053 mm) . Compared with CK, all treatments could enhance the stability of aggregates, DP treatment significantly increased the MWD and GMD, and RS treatment significantly increased the proportion of aggregates larger than 0.25 mm by 9.11%. Compared with CK, the content of organic carbon in aggregates of different treatments increased, and the contribution rate of organic carbon increased at first and then decreased with the decrease of particle size, the contribution of 8 ~ 2 mm aggregates to SOC was 117.75% higher than that of CK, and the contributions of 2 ~ 0.25 mm aggregates to SOC were 3.32% and 26.44% higher than that of BC and DP. The results of correlation analysis, redundancy analysis, and partial least squares path model analysis indicated that maize yield was closely related to soil environmental factors such as aggregate organic carbon and aggregate stability. MWD and R_0.25 were significantly positively correlated with maize 100-grain weight, and organic carbon in aggregates ranging from 2 to 0.25 mm was the main factor affecting maize yield. The application of organic materials could indirectly regulate yield by affecting aggregate organic carbon.

Conclusion The application of organic materials can not only improve the formation of macroaggregates and the stability of soil structure, but also regulate the level of organic carbon reservoir and promote the soil fertility of yellow soil.