Effects of potassium fertilization on winter wheat under different production practices in the North China Plain

Haplic Luvisols with low to medium grade of potassium occur in major agricultural regions of north China. Moreover, unbalanced fertilization has rapidly depleted soil available potassium (K) and hence caused significant yield response to K fertilization in many intensive farming systems. Our specific objectives in this study were to determine winter wheat (Triticum aestivum L.) response to K fertilization on Haplic Luvisols in the North China Plain (NCP) as affected by conventional as well as high-yielding production practices. Four field experiments were conducted in the NCP. The factorial study compared three levels of K fertilization (K0=no K; K1=medium K rate; K2=high K rate) and two levels of production practices: conventional (CP) and high yielding (HP). A significant positive wheat yield response to K fertilization was obtained under both CP and HP at all site-years. On average, K fertilization significantly increased all three yield components measured, namely kernel number per spike, spike number per hectare and kilo-grain weight. Overall, HP outperformed CP in terms of wheat grain and biomass yield. Nutrient use efficiency of N and P was increased by K application, especially under HP. Overall, HP surpassed CP with regard to partial factor productivity of N and K (PFPN and PFPK) across the four site-years, whereas the opposite trend was found for partial factor productivity of P (PFPP) due to increasing P input. Negative K balances were observed in all of the treatments in both years and under both production practices, especially under HP. Economic profits were achieved under both production practices, but there were no significant differences between CP and HP on average, across four site-years. Therefore, farmers who are planting wheat on Haplic Luvisols in the NCP must take account of the K fertility of their soils for sustainable crop production.