The suitable potassium fertilizer rate in spring maize in hilly area of central Sichuan Basin, China

【Objectives】 A field experiment was conducted for two consecutive years (2013 and 2014) to study the suitable potassium application rate for high grain yield and potassium (K) use efficiency, to provide a scientific basis for K management in spring maize production in the hilly area of central Sichuan Basin, China. 【Methods】 A spring maize cultivar Zhenghong 505 was used, and a randomized complete block experiment was conducted with five K2O application rates of 0, 45, 90, 135 and 180 kg/hm2, in the base of application of N 225 kg/hm2 and P2O5 90 kg/hm2, respectively. Plant samples were collected in big trumpet period, silking stage, filling stage, mature stage for the determination of plant dry weight and K contents. The plant K accumulation, K translocation and use efficiency were calculated.【Results】As applied K increasing from 0 to 180 kg/hm2, the grain yield and the agronomic efficiency of K increased first, then gradually decreased; the K physiological efficiency and K recovery efficiency decreased. The K uptake efficiency, K fertilizer efficiency and partial factor productivity reduced significantly except K harvest index. According to the simulated results, the maximum grain yield of maize would be obtained in K2O application rate of 96.1 kg/hm2. For production of 100-kilogram grain, it needs to absorb K2O of 1.55 kg. K was mainly absorbed before silking stage, the percentage was 72.7%-88.9% of total K uptake, in early filling stage there was still a relatively high absorption and accumulation. Most K in grains came from transfer from nutritive organ, and higher application of potassium fertilizer resulted in higher potassium transfer to grains.【Conclusions】 Under the experimental condition, the optimal K fertilizer rate was K2O 90 kg/hm2 for high yield and high K use efficiency.