Effects of the usual controlled-release potassium chloride (CRK1)

the high controlled-release potassium chloride (CRK2)

the usual mixed potassium chloride with controlled-release potassium chloride (BBF1) and the high mixed potassium chloride with controlled-release potassium chloride (BBF2) on maize yield

potassium use efficiency

and soil available potassium were investigated in a 2-year field experiment using maize-wheat rotation system

and the none potassium (CK)

the usual potassium chloride (K1) and the high potassium chloride (K2) were set up as controls. To provide the basis for application of controlled release potassium chloride

studied the synchronous nutrition relationships of between controlled-release fertilizers with maize. The results showed that: (1) The yield of maize under BBF2 treatment in 2014 and 2015 were 11 697.8 kg/hm2 and 11 921.1 kg/hm2

respectively. Compared with K1 treatment in the 2014 and 2015

the yield increased by 13.3% and 15.7%

respectively and the incomes increased 16.6% and 19.6%

respectively. (2) The agronomic potassium use efficiency under BBF2 treatment was greater significantly by 49.0% and 41.9% over those of the K1 treatment in 2014 and 2015

respectively. The physiological potassium use efficiency under BBF2 treatment was greater significantly by 17.6% and 34.8% over those of the K1 treatment in 2014 and 2015

respectively. The highest apparent potassium use efficiency occurred in BBF1 treatments

which were 23.73% and 35.22% in 2014 and 2015

respectively. (3) Plant height and stem diameter were significantly increased with potassium fertilizer application. Maize plant height increased under BBF2 treatment from the later tasseling stage to the mature stage. Both CRK and BBF treatments increased significantly the leaf SPAD values of the late tasseling stage

and significantly improved the absorption of potassium and enhanced grain filling properties. The results indict that the application of the mixed potassium chloride with controlled-release potassium chloride can meet the maize nutrition requirement of different growth period

and improved maize yield and potassium use efficiency

among which

BBF2 treatment is the optimal fertilization scheme.