The relations of grain yield with different agricultural practice composit ion for "Chang-Nong No. 4" c. v. were studied by using second-degree polynomial regression analysis and orthogonal rotation design. Experimental results Showed that plant density was a vital agricultural factor for soybean high yield. Application of nitrogen fertilizer and Phosphoric fertilizer were importent for further high yield. However, the potassium fertilizer worked less.
yield of 150kg/mu or more would be obtained by means of plant density 10000 Plant/A, with appling urea 5.5～6.0kg/mu, Phosphoric fertilizer 9.5～10kg/mu and potassium fertilizer 3 kg/mu.