Abstract: Using the method of multiple factors .full dimension, and cross replication fixed experiments, the rotation,fertilization,and tillage system for improving black soil fertility, increasing crop yield, and enhancing benefits were investigated. The results demonstrated that: four crops rotation system taken soybean as center, fertilization system taken manure as the main in combination with inorganic fertilizer,and the tillage system taken rotating plow as focus in combination with harrowing and loosening were the technological system in improving black soil fertility,increasing yield,and enhancing efficiency. The three systems mentioned above formed the cropping system of black soil improvement, which was the efficient approach and guaranteed method to develop high yield,high efficiency,and high quality agriculture in the black soil area at Songnen Plain.

Key words: leaf hydraulic conductance, xylem cavitation, CO₂ fixation, Acacia mangium.