Potassium chloride, superphosphate, and urea were used as P, K and N fertilizers, respectively. The N fertilizer for maize was divided into two applications, 72 kg N ha-1 for base fertilizer and the rest for topdressing. The P and K fertilizers were used as base fertilizers at 105 kg P2O5 ha-1 and 112.5 kg K2O ha-1 for maize and 63 kg P2O5 ha-1 and 52.5 kg K2O ha-1 for soybean, respectively. All fertilizers were base placement, except for the RN treatments in the maize-soybean relay strip intercropping system. In RN and CN, the N fertilizer for maize was divided into two applications, 72 kg N ha-1 for base fertilizer and the rest for topdressing. Under RN treatment, the base N fertilizer for IM was base placement. The N topdressing for IM was integrated with the soybean base fertilizer and strip placement, with a distance of 25 cm from maize rows to soybean rows in IMS (the optimizing of fertilization methods, unpublished data).