Abstract: The clayey farmland soil in black soil region of Northeast China, due to the existence of thicker plough pan created by unreasonable tillage, is a main limiting factor for local agricultural production. In this paper, a field experiment was conducted to study the construction effect of fertile cultivated layer on crop yield, soil physical properties, soil moisture content, and soil microbial number. After the construction of fertile cultivated layer, the soil had a thicker cultivated layer, and the crop yield was increased. Comparing with traditional tillage, applying straw and organic manure into 20-35 cm soil layer decreased soil bulk density by 9.88% and 6.20%, increased soil porosity by 9.58% and 6.02%, and enhanced soil saturated hydraulic conductivity by 167.99 and 73.78%, respectively, indicating that the construction of fertile cultivated layer could improve soil aeration and water permeability, and enhance the infiltration of rainfall. The soil moisture content and water use efficiency under the application of straw and organic manure into plough pan were higher than those under traditional tillage, and a positive correlation was observed between the moisture content in 0-35 cm soil layer and the emergence of maize seedlings. Due to the increased organic carbon source and aeration in the constructed fertile cultivated layer, soil microbial number was also increased.

Key words: black soil, fertile cultivated layer,  construction effect, the Yellow River irrigation area of Ningxia, swine manure, winter wheat field, nitrate N, leaching.