ObjectiveControlled release of potassium chloride can achieve slow release of potassium ions synchronized with crop absorption, while ensuring the effectiveness of potassium ions in the soil, meeting the demand for potassium in the later stage of crop growth, and significantly improving the utilization rate of potassium fertilizer. Exploring the effects of long-term application of controlled-release of potassium chloride and its mixed fertilizers on maize yield and quality, providing technical support for achieving high-quality maize production.MethodsBased on the long-term field experiment of controlled release potassium chloride applied to summer maize (Zea mays L., Zhengdan 958) (started in 2014), six treatments were set up: no potassium fertilizer (CK), constant ordinary potassium chloride (K), constant polyurethane coated potassium chloride (CRK1), 1/3 potassium reduction polyurethane coated potassium chloride (CRK2), constant mixed potassium chloride (BBF1) and 1/3 potassium reduction mixed potassium chloride (BBF2). Relevant indicators such as maize growth, soil potassium supply level, potassium uptake capacity, photosynthesis, etc. were measured during the tasseling stage, and relevant indicators such as maize quality and agronomic benefits were determined during the maturity stage.Results1) Compared with K treatment, CRK1, BBF1, CRK2, and BBF2 showed an increase in yield of 9.82%, 12.06%, 7.13% and 10.68%, respectively. The aboveground biomass increased by 9.22%, 10.44%, 4.16% and 6.09%, respectively, and the economic benefits increased by 16.29%, 28.37%, 14.15% and 21.12%, respectively. 2) The potassium ion content in CRK1 and BBF1 increased by 19.93% and 13.89% respectively compared to K treatment; The chlorophyll SPAD values of CRK1 and BBF2 increased by 7.32% and 6.59% compared to K treatment; The leaf area index LAI value of CRK1 increased by 7.04% compared to K; The net photosynthetic rate of CRK1 and CRK2 increased by 18.58% and 18.66% compared to K. 3) Compared with K treatment, the starch content of CRK1, BBF1, CRK2, and BBF2 increased by 4.27%, 2.51%, 9.32% and 7.16%, respectively, while the oil content increased by 5.65%, 3.11%, 6.63% and 5.92%, respectively; The crude protein content of CRK1 and CRK2 increased by 4.23% and 1.06% respectively compared to K treatment. Compared with K treatment, CRK1, BBF1, CRK2, and BBF2 increased starch production by 14.73%, 19.10%, 17.56% and 18.96%, crude protein production by 14.47%, 14.04%, 8.27% and 8.03%, and oil production by 16.03%, 19.67%, 14.27% and 17.23%, respectively.ConclusionControlled release potassium chloride can meet the potassium requirements for maize growth and quality formation, improve maize growth, optimize maize grain quality traits, and significantly improve maize yield and potassium fertilizer utilization efficiency when mixed with ordinary potassium chloride. It also reduces fertilizer input costs and achieves the goal of reducing production and quality.