The Impact of Tillage Depth and Straw Incorporation on Crop Yield and Soil Water Supply in Arable Black Soil

Black soil is one of important arable soil in China, tillage depth and straw incorporation both impacted the agricultural production of black soil. The impact of tillage depth and straw incorporation depths on maize and soybean yield were considered based on a three-year field experiment which is a split block design. The main treatments included shallow cultivation within 0~15 cm (D15), medium-shallow cultivation within 0~20 cm (D20), deep cultivation within 0~35 cm (D35)and 0~50 cm (D50),secondary treatments included contrast and straw incorporation (+S). Yields of maize and soybean were increased along with the increase in cultivation depth, and obtained the greatest values of 8 999 kg·hm^-2 and 2 424 kg·hm^-2, respectively, suggesting that the cultivation depth was an important factor impacting crop yield. Straw incorporation within 0~15 cm (D15+S),0~20 cm (D20+S),0~35 cm(D35+S),0~50 cm(D50+S)were added after each cultivation depth treatment was split. Comparison with corresponding no straw incorporation treatments, maize and soybean yields were decreased when cultivation depth was ≤ 20 cm, but were increased when cultivation depth was ≥ 35 cm, and obtained the greatest yield in D35+S treatments, which suggested that the depth of straw incorporation was key factor impacting the role of straw incorporation. Comparison with D15+S, soil water content in 0~15 cm soil layer, crop emergence rate and soil water supply under D20+S, D35+S and D50+S treatments were increased by 7.8%~12.6%, 11.4%~16.9% and 6.7%~10.4%, respectively, suggesting that above factors could regulate the role of straw incorporation. D50 and D50+S treatments increased maize and soybean yields, but increased also mechanical operation cost and was not in favor of soil water conservation. Therefore, combination of 0~35 cm cultivation depth and straw incorporation was recommended with the objectives of increasing crop yield and rainfall use efficiency in study site.