Effects of NPK fertilizer management on nutrient use of kenaf，Hibiscus cannabinus L.

【Objective】 The effects of NPK fertilizer management on nutrient contents and uptakes in different organs and soil available nutrient contents were studied to investigate the nutrient use of different kenaf varieties, so as to provide rational fertilization for high yield and high efficient cultivation of kenaf. 【Method】 The pot experiments included two kenaf varieties, i.e. Fuhong 992 and Hongyou 2, three fertilization levels, i.e. low fertilization (N 0.10 g·kg^-1, P₂O₅ 0.05 g·kg^-1 and K₂O 0.10 g·kg^-1), medium fertilization (N 0.15 g·kg^-1, P₂O₅ 0.075 g·kg^-1, K₂O 0.15 g·kg^-1) and high fertilization (N 0.20 g·kg^-1, P₂O₅ 0.10 g·kg^-1, K₂O 0.20 g·kg^-1), and three fertilization methods, i.e. T₁ (all N and K fertilizers as basal fertilizer), T₂ (60% N and K fertilizers as basal fertilizer, 40% N and K fertilizers as topdressing) and T₃ (all N and K fertilizers as topdressing).【Result and conclusion】 The contents of N, P and K in various organs, plant NPK uptakes and the contents of available N, P and K in soil increased with the increase of fertilizer rate. With the increase of the rate of NK for top dressing, N contents in various organs, P contents in root, leaf and pole and plant N and P uptakes reduced while P contents in bark, K contents in various organs, plant K uptakes and the contents of available N, P and K in soil increased. In this study, for Fuhong 992 and Hongyou 2, high fertilization with all N and K fertilizers as basal fertilizer can increase the nutrient absorption of kenaf and the contents of available nutrients in soil.