[Effects of different kinds of organic fertilizer on fruit yield, quality and nutrient uptake of watermelon in gravel-mulched field].

The effects of different kinds of organic fertilizer on the growth, yield, quality, and nutrient absorption and utlization of watermelon were examined to provide theoretical basis for adequate fertilization and efficient production of watermelon in gravel-mulched field in the Loess Pla-teau of Northwest China. The growth index and nutrient absorption at main stages of growth and development, yield and quality of watermelon were compared among treatments of applying chemical fertilizer (CK), cattle dung, chicken manure, sheep manure and pig manure which contained the equal amount of nitrogen, phosphorus and potassium. The results showed that vegetative growth index, nitrogen and potassium transportation were promoted, yield and nutrient accumulation were improved in treatments of cattle dung, chicken manure and pig manure. Compared to chemical fertilizer, the fruit yield increased by 27.4%, 31.6% and 30.2%, respectively, nitrogen accumulation improved by 26.3%, 39.8% and 47.4%, phosphorus accumulation increased by 49.3%, 48.3% and 55.9%, potassium accumulation improved by 35.8%, 41.6% and 51.9%, respectively, under cattle dung, chicken manure and pig manure treatments. The quality of watermelon was better in pig manure treatment among all the treatments. The central and edge sugar content of watermelon increased by 5.5% and 11.6%, respectively, and Vc content increased by 19.9%, compared with the chemical fertilizer treatment. There was no significant difference between sheep manure and chemical fertilizer treatments. In conclusion, chicken manure and pig manure were optimal organic fertilizers for watermelon planting in gravel-mulched field. The application of sheep manure should be avoided or reduced.