Abstract: Straw incorporation is one of the important practices in increasing soil fertility, which is impacted by the depth of straw incorporation.The effect of corn stalk incorporated into different black soil depths on soil organic matter(SOM) and nutrient content was tested in this study based on a three-year field experiment.Four treatments were designed as follows:the corn stalk amount of 10 000 kg·hm^-2 was incorporated into 0-15 cm(D15S), 0-20 cm(D20S), 0-35 cm(D35S) and 0-50 cm(D50S) soil depths, respectively.The results showed that contents of stalk in soil(SC) ranged from 1.68 g·kg^-1to 6.06 g·kg^-1, with an increasing trend of D15S>D20S>D35S>D50S.Stalk incorporation increased SOM in a given soil layer, compared with D15S treatment, and SOM contents in D20S, D35S and D50S treatments decreased by 27.3%, 48.4% and 67.8%, while the ratio of stalk converted to SOM reached a largest value in D35S treatment and increased by 28.6%, 32.6% and 17.5%, compared with D15S, D20S and D50S treatments, respectively; the increased amount of SOM in whole soil layers from different treatments showed an increasing trend of D35S>D50S>D15S>D20S; and soil light fraction organic carbon showed the similar trend as SOM.Soil total nutrient contents were not impacted by stalk incorporation, but soil available nutrient contents were impacted significantly(P<0.05).Compared with initial values, the contents of soil available nitrogen, available phosphorous and available potassium increased by 7.17%-20.6%, 9.16%-38.2% and 12.6%-43.7%, respectively; the greatest increase ratio in D35S indicated that more soil nutrients were cumulated in deep soil by deep straw incorporation, which increased the supply of soil nutrients.Therefore, we suggest that the optimum depth of corn stalk incorporated in soil would be 0-35 cm soil depth, which would increase the contribution of stalk incorporation to soil fertility, and realize black soil protection.