西瓜需肥特点与平衡施肥研究

西瓜在整个生育期中吸收K最多,N次之,P最少。吸肥量以发芽期最少,幼苗期较少,抽蔓期增多,果实膨大期达高峰,成熟期又缓慢减少。K施量达180kg/hm2时,产量和品质最高,超过此量均有下降趋势。N肥以底施加追施的方法单产最高;K肥中以K2SO4底施单产最高,追施使瓜瓤含糖量增高;对高、中、低肥力的土壤,N、P最佳施用量(kg/hm2)分别为126、61.5;174、73.5;210、124.5。低肥力地块,地力(不施肥)生产率和有机肥、N、P、K肥生产率分别为41.9％、11.5％、28.0％、13.3％、5.3％。

Studies on the Nutrients Uptake and Balanced Fertilization of Watermelon

In the whole growing period, watermelon absorbed the most quantity of K, more quantity of N and less quantity of P. The guantity of nutrients uptaked was lest in sprouting stage, less in seedling stage, more in creeping stage, the most in fruit inflating stage, and less in mature stage. The feature of nutrient uptaked appeared less-more-less tendency in the whole period. The yield and quality was highest when K 180kg/ hm2 was fertilized, and lower when nutrients was increased over this point. The highest yield would be got when nitrogen was applied in the way of combination basal with top dressing basal application of K2SO4. compared with other K fertilizers, but when K2SO4 was applied in top dressing way. the higher sugar content would be got. In the high, middle and low fertile soils, the optimal N. P application amount were 126. 61.5; 174, 73.5; 210, 124.5kg/hm2. respectively. In the low fertile field. 41.9% of yield was contributed from the soil itself. 11.5% from manure. 28.0% from N fertilizer, 13.3% from P fertilizer, and 5.3% from K fertilizer.