Physical and chemical properties of Camellia oleifera shell composts with different additives and its maturity evaluation system

The effects of different additives on the compost of Camellia oleifera shell were characterized and a maturity evaluation system for the obtained compost was established. Four treatments were designed as C. oleifera shell with C. oleifera seed meal (A1), with C. oleifera seed cake (A2), with sheep manure (A3), and with spent mushroom substrate (A4). A3 had the longest thermophilic phase (over 50 °C) and shortest cooling phase. Compared with A1, the thermophilic phase of A2 was postponed 11 days due to the high lipid content, but terminated almost at the same time. The temperature of A4 increased slowly and took longer time to reach ambient. C/N, pH, E4/E6, and NH4+-N decreased along with composting process, while TN, GI, and NO3−-N were opposite. Based on the Pearson correlation analysis with the Solvita maturity index as a reference, the result indicated that TN, C/N, GI, NH4+-N, and pH can be used for the maturity evaluation.