High-Yield Maize Production in Relation to Potassium Uptake Requirements in China

Understanding maize (Zea mays L.) grain yield in relation to K uptake requirements is essential for devising optimized K fertilizer management practices and agricultural policies to increase grain yield for food security. A database comprising 953 measurements was created using 56 on-farm and research station experiments during 2000 to 2012 in the North China Plain (NCP) to determine K uptake requirements and patterns of K accumulation pre- and post-silking with different yield levels. The K requirement Mg-1 grain yield (K-req.) in the K = Opt. treatment was 15.0 kg, which was lower than 20.0 kg in the K > Opt. treatment. In the Optimal K treatment, average Kreq. values were 15.0, 14.8, 14.8, and 15.7 kg for grain yields ranging from <8.0, 8 to 10, 10 to 12, and >12.0 Mg ha(-1), respectively. The relative consistency of Kreq. values with increasing grain yield was mainly attributed to an offset in the increase in stover K (from 14.0 to 18.1 g kg(-1)), an increase in harvest index (HI) from 0.49 to 0.54, and the stability of grain K concentrations (about 3.2 g kg(-1)). Higher percentages for K accumulation at the post-silking stage were observed with > 12 Mg ha(-1) (24%) and 10 to 12 Mg ha(-1) (22%) compared to < 10 Mg ha(-1) (9%). In conclusion, maintaining adequate K supply and post-silking K accumulation is essential for achieving high-yield maize production.