Key soil nutrient requirements for different yield levels in North China

Soil chemical properties are closely related to crop production levels. Understanding the relationships between soil nutrients and different yield levels is important for improving the efficiency of fertilization management programs. The objectives of this study were to understand the key soil nutrient requirements for different crop yield levels using 10 experimental wheat-maize rotation sites and to optimize fertilization applications in North China. The results found significant differences between the soil chemical properties among the study sites, with average contents in the range of 10.07-14.72 g/kg for soil organic carbon (SOC), 0.38-1.29 g/kg for total nitrogen (TN), 56.43-89.77 mg/kg for available nitrogen (AN), 17.36-48.54 mg/kg for available phosphorus (AP), 79.4-184.5 mg/kg for available potassium (AK), 0.78-5.97 mg/kg for soil Cu, and 0.75-2.20 mg/kg for soil Zn. The soil pH values were 6.46-8.19. Significant correlations (p < 0.05) were found between high-level yields and higher contents of SOC, TN, AN, and AP when a suitable soil pH were present. The higher levels of soil SOC and TN were important for maintaining high-level yields in these regions. Soil AN and pH are two key limitations that could significantly (p < 0.05) improve medium-level yields. Although some soil indicators, including SOC, TN, AN, AP, soil pH, soil Zn, and Cu could significantly influence low-level yields, soil amendments with C, N, and available P and having a suitable soil pH were especially important for improving low-level yields. These results could be used to improve conventional methods of fertilization management and increase the efficiency of fertilizer use in North China.