| Abstract: In order to achieve the goal of chemical fertilizer reduction and high quality and high yield of watermelon in Xiangshui county, the effect of different proportion organic fertilizer (30%, 60%, 90%) instead of partial chemical fertilizer on the yield, sugar content and soil fertility of watermelon in greenhouse under the condition of equal nitrogen were studied. The results showed that under the treatment of replacing partial chemical fertilizer with organic fertilizer, the yield of watermelon increased, the greater the amount of substitution, the higher the yield. When the amount of substitution reached 90%, the yield of watermelon increased significantly. Partial replacement of chemical fertilizer with organic fertilizer could promote the growth and development of watermelon, increasing the length of main stem, the number of leaves and the number of nodes. It could also increase the sugar content of watermelon, and the sugar content was the highest when the substitution amount reached 30%, 5.23% higher than the contrast. In addition, the available phosphorus and available potassium increased with the increase of organic fertilizer substitution. According to the comprehensive factors of yield and quality, 30%-60% of organic fertilizer was the best substitution amount for chemical fertilizer. |