Abstract Optimal potassium (K) fertilization is beneficial for oilseed‐rape ( Brassica napus L.) yield and quality. However, the discrepancy between the high K demand of winter oilseed rape and low soil fertility and insufficient potassium input has limited the sustainable development of oilseed‐rape production. A series of on‐farm experiments in the key winter oilseed‐rape domains of China was conducted from 2004 to 2010 to evaluate K‐fertilizer management for winter oilseed rape. Currently, the average NH 4 OAc‐extractable K content in the 0–20 cm soil layer is 89.1 mg kg –1 indicative of “slight deficiency”. In addition, farmers in China usually fail to use sufficient K fertilizer in oilseed‐rape production, the average mineral‐potassium‐fertilizer input in 2010 being only 35 kg K ha –1 , far lower than the recommended rate of potassium for winter oilseed rape. Adequate potassium fertilization significantly raises seed yield. The average yield‐increase rate for the major production regions due to K‐fertilizer application was 18.5%, and the average K fertilizer–use efficiency 36.1%. Based on the negative correlation between yield response to potassium fertilization and available soil K content, a soil‐K‐test index was established for winter oilseed rape with a threshold value for NH 4 OAc‐extractable soil K of 135 mg kg –1 . When available soil K‐content is below this threshold value, more K fertilizer should be applied to achieve high seed yield and to increase soil fertility. The major challenge for K‐fertilizer management in winter oilseed‐rape production in China will be to guide farmers in the different regions in making reasonable use of K fertilizer through soil K‐testing technology in order to maintain both seed yield and soil fertility.
[Objective] The aim was to discuss the effects of nitrogen phosphorus and potassium fertilizers on yield and economic benefit of late rice.[Method] Jinyou 402 was taken as tested late rice for fertilizer effect experiment in order to analyze the effects of nitrogen phosphorus and potassium fertilizers on yield and economic benefit of late rice,and combining with production practice,the fertilizer application amount was determined by establishing fertilizer effect model.[Result] The yield and economic benefit of late rice increased significantly with nitrogen and potassium fertilizer application and their highest yield gain were 1 288 and 555 kg/hm2,the corresponding increscent rate were 23.7% and 8.8%,and the net income were 1 195 and 350 yuan/hm2,respectively.However,the effect of phosphorus fertilizer was not remarkable.Combining with factual condition and according to fitting one-place quadratic fertilizer effect model,fertilizer application amount of nitrogen phosphorus and potassium fertilizers for highest yield were 149,61 and 116 kg/hm2,the optimum fertilizer application amount for the highest economic benefit were 122,46 and 45 kg/hm2,respectively.[Conclusion] Late rice had obvious high-yield and economic benefit effect by rational fertilization.However,when fertilizer application amount exceeded a certain range,the yield and economic benefit of rice showed downtrend.
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