关键词: 鉴定, 鉴定

Abstract: Nitrogen fertilization tends to cause over-growth of sweet potatoes and leads to the yield decrease. Pragmatically, farmers apply relatively low quantity of nitrogen fertilizers to guarantee their sweet potato yield. In doing so, the insufficient application of nitrogen limits their yield potential. In this study, field experiments were designed to understand the relationships between fertilizing management (i.e. different amount of nitrogen and different potassium formulas) and yield and growth of sweet potatoes cultivated on lime concretion black soil. The results could be used to establish an optimal fertilization strategy for high yield sweet potato production. Results showed that fertilization promoted the growth of above-ground organs more than the underground tubers. More fertilizers applied, greater the differences were. In Treatment 1, which was applied with high amount of potassium sulfate (K2SO4) as the only potassium source, the over-growth of above-ground organs was observed. Yield was 3.7% decreased compared with the local fertilizing tradition. In Treatment 2, where half of the potassium was applied as potassium chloride (KCl), could realize a balanced growth promotion in both the underground and above-ground organs. Such fertilization gained 6.2% of yield increase compared with the traditional fertilization, and 10.4% yield increase compared with Treatment 1. Once the nitrogen was increased from 124.5 kg/hm2 in the traditional fertilization to 225 kg/hm2, potassium chloride was proved to be the key nutrition element of yield increase. Compared with solo potassium sulfate application, integration of potassium chloride and potassium sulfate significantly increased the absorption of various nutrients, such as nitrogen, phosphorus and potassium. Results suggested that the traditional fertilization for sweet potatoes cultivated on lime concretion black soil, which applied non-chloride potassium fertilizers, limited the yield increase of the crop. Further studies were thus needed to establish an optimal strategy of potassium fertilization for high yield sweet potato production.