Effect of short-term combined application of organic fertilizer and chemical fertilizer on topsoil properties and productivity of summer maize in a medium-productivity meadow-cinnamon soil

Abstract

Combined application of organic fertilizer and chemical fertilizer (CAOFCF) is gaining more attention in sustainable agriculture production. However, it remains unknown whether short-term CAOFCF can improve soil properties and maize productivity simultaneously in a medium-productivity meadow-cinnamon soil. In this study, a 3-year (2019-2021) field experiment was established by arranging five treatments: (1) CF, applying chemical fertilizer alone; (2) OFCF1, 15% OF + 85% CF; (3) OFCF2, 30% OF + 70% CF; (4) OFCF3, 45% OF + 55% CF; (5) OFCF4, 60% OF + 40% CF. The results showed that short-term CAOFCF significantly increased topsoil aggregate stability with higher percentage of macro-aggregate and mean weight diameter in topsoil. Moreover, CAOFCF reduced soil bulk density and increased SOC sequestration in topsoil compared to CF, especially for OFCF3 and OFCF4. Although the soil bacterial diversity of CAOFCF treatments differed no significantly with CF, OFCF1 and OFCF2 obviously increased soil urease, sucrase, and acid phosphatase activities. Additionally, CAOFCF improved the relative abundance of Actinobacteria and Chloroflexi, as well as bacterial functional abundance. Compared with CF, OFCF1 and OFCF2 increased the root biomass, above-ground biomass, and grain yield (p<0.05), but the difference in these indexes among CF, OFCF3 and OFCF4 were not obvious. The correlation analysis indicated that there is no direct correlation between soil properties and grain yield. Nevertheless, the soil urease and sucrase activities were positively correlated with root biomass and root to shoot ratio, and root biomass and root to shoot ratio were positively correlated with above-ground biomass and grain yield. Overall, short-term CAOFCF with lower application amount of organic fertilizer (i.e. 1.36-2.72 Mg ha ) can improve topsoil physicochemical properties, soil enzymatic activities, as well as maize productivity in a medium-productivity cinnamon soil, the higher crop productivity was mainly attributed to the improved root system driven by urease and sucrase activities.