Incorporation of granulated organic materials boosts soil quality and multifunctionality in infertile croplands

As an innovative technology, incorporation of massive granulated organic materials has been proven effective in boosting soil organic carbon (SOC) in infertile croplands, but its effects on the soil quality index (SQI) and multifunctionality (SMF) remain unclear. Two micro-plot experiments were conducted in infertile upland and paddy, in which granulated organic materials were incorporated at four straw doses (0, 30, 60, and 90 t ha^-1) and three formulas (straw, straw + manure, and straw + manure + biochar) at the dose of 60 t ha^-1. After one year, the incorporation of granulated organic materials rapidly improved SQI and SMF in both upland (21.0%-84.9% and 13.8%-168.7%, respectively) and paddy (31.0%-49.7% and 17.9%-272.4%, respectively). With the increasing doses of granulated straw incorporation, SQI increased progressively in upland, whereas no significant differences among the three doses were detected in paddy, likely attributed to the inhibited decomposition of granulated organic materials at high dose under moist-irrigated paddy. SMF increased linearly with incorporation dose in both croplands by improving acquiring enzyme activities. Under the equivalent incorporation dose, the increases of SQI and SMF were the highest for the formula of straw + manure in upland and the formula of straw + manure + biochar in paddy. The incorporation of granulated organic materials increased the crop yield by 44.8%-77.6% in upland and 33.1%-64.1% in paddy. The increases of SQI and SMF were positively correlated with crop yield in upland but not in paddy. Thus, the single-time incorporation of massive granulated organic materials into the plough layer is effective strategy for rapid enhancement of soil quality and crop yield for infertile croplands.