Objectives Banana production requires large amount of water and nutrient supply, especially K nutrition. We studied the response of banana yield, quality, efficiency and soil potassium balance to different potash input levels, to serve the integrated nutrient and water management in Fujian banana production.

Methods A three-year fixed-site experiment was carried out from 2016 to 2018. With the same N and P input, five treatments were set up, K₀ (no K input) and K₁ (K input rate of 1400 kg/hm²) treatment were under conventional irrigation, and K_0.4, K_0.6 and K_0.8 (applying 40%, 60% and 80% of K rate in K₁ treatment) were under drip irrigation. At maturing stage, the banana yield, quality, K uptake and soil K balance were investigated.

Results The 3-year average yield of K_0.4, K_0.6, K_0.8 treatments were –11.5%, 2.4% and 13.5% higher than that of K₁, respectively. Compared with K₁, the growth, single banana size and weight under K_0.4 were significantly lower; The growth of K_0.6 and K_0.8 were similar to those of K₁, the fruit number and single fruit size and weight under K_0.6 were similar, while the fruit number and single fruit size and weight under K_0.8 were significantly higher. The average three-year net income was in descent order of K_0.8 (54179.4 yuan/hm²) > K_0.6 (46663.7 yuan/hm²) > K₁ (42538.1 yuan/hm²) > K_0.4 (36808.1 yuan/hm²), and the net income differences among them were all significant. After three years of continuous plantation of banana, the soil K was apparently deficit in K₀ (–406.5 kg/hm²) and K_0.4 (–93.3 kg/hm²), basically balanced in K_0.6 (8.9 kg/hm²), and surplus in K_0.8 (220.4 kg/hm²) and heavily surplus under K₁ (501.9 kg/hm²).

Conclusions Integrated considering yield, quality, economic benefits and soil potassium balance, the proper decreasing rate of potash is 20% under drip irrigation in banana orchards in Fujian Province.