Abstract:
Objective Soil physical-chemical properties and the number of bacteria and fungi at different depths (0 ~ 20 cm and 20 ~ 40 cm) were investigated to comprehensively evaluate the effect of straw returning with decomposing microbial inoculants on paddy soil.
Method A field experiment with six treatments, including check control without straw returning and fertilizer (CK), fertilization + no straw returning (RT), fertilization + straw returning + 7.5 kg hm−1 decomposing inoculant (M1), fertilization + straw returning + 15 kg hm−1 decomposing inoculant (M2), fertilization + straw returning + 30 kg hm−1 decomposing inoculant (M3), and fertilization + straw returning (ST), was set up to determine the soil physical-chemical properties and the abundance of bacterial ang fungal community, in order to obtain a better decomposing inoculant dosage through the results of the gray correlation analysis.
Result With the addition of decomposing inoculants, the straw decomposition rate was significantly enhanced by 53.49% on average. Compared with ST, only M1 significantly increased the content of available potassium by 49.45% in 0 ~ 20 cm soil, and total phosphorus, available nitrogen, and available potassium by 19.80%, 19.34%, 25.65% in 20 ~ 40 cm soil. Only M3 significantly increased R0.25 and fungi copies in 0 ~ 20 cm soil by 16.34% and 89.06%. M2 and M3 significantly enhanced MWD, GMD in 0 ~ 20 cm soil, and M3 was the highest. M2 and M3 also significantly increased R0.25, MWD, GMD, available phosphorus, and bacterial gene copies in 20 ~ 40 cm soil, and M3 had higher values than M2 except for available phosphorus. According to the results of the gray correlation analysis, M3 was the optimal choice to improve the soil quality among 6 treatments.
Conclusion Straw returning with 30 kg hm−1 decomposing microbial inoculants was a better way to improve the soil quality both in 0 ~ 20 cm and 20 ~ 40 cm soil.
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