[Effects of Mushroom Residue Application Rates on Net Greenhouse Gas Emissions in the Purple Paddy Soil].

China is the leading country for production of edible mushrooms and also outputs numerous mushroom residues. The recycling of mushroom residue can solve environmental pollution problems, provide nutrients for the farmland, and play an important role in reducing greenhouse gas emissions and increasing soil carbon sequestration capacity. In order to investigate the effects of mushroom residue amounts on net greenhouse gas emissions in purple paddy soil, potted experiments using static opaque chamber and gas chromatography methods were used to study the changes of greenhouse gases, soil carbon sequestration, and net greenhouse gas emissions (NGHGE) in the paddy soil with five treatments: no fertilizer (CK), conventional fertilization (NPK), 9 t·hm-2 mushroom residue+NPK (LM), 18 t·hm-2 mushroom residue+NPK (MM), and 36 t·hm2 mushroom residue+NPK (HM) from March 2017 to September 2017.The results showed that: ① The greenhouse gas emissions (including CH4, CO2, and N2O) increased with increasing additions of mushroom residue. The emissions of CH4 from highest to lowest followed: HM > MM > LM≈NPK > CK. The HM treatment significantly increased the CH4 emission flux (P<0.01) more than the other treatments and showed an obvious single peak curve, while the CH4 emission flux with the LM treatment showed a bimodal curve, and the MM treatment showed a multiple peak curve. The CO2 emission flux followed: MM > NPK≈LM > HM > CK; and the curves for the LM, MM, and HM treatments were a single peak curve, bimodal curve, and multiple peak curve, respectively. The N2O cumulative emission from the NPK treatment was significantly higher than with the other treatments. The N2O emission flux of the NPK treatment was a bimodal curve and that of the HM treatment was a single peak curve, while the N2O emission flux of treatments LM and MM showed multiple peak curves. ② The carbon sequestration capacity with the LM treatment was lower than that of the other treatments and that from the MM treatment was the highest. The carbon sequestration capacity of the MM treatment increased by 59.2% compared to that of the NPK treatment and increased by 87.79% and 65.65% compared to that of the LM and HM treatments. The LM treatment has the highest carbon sequestration capacity, which was higher than that of the NPK and MM treatments and about 2.1 times greater than the CK treatment and HM treatment. ③ The minimum NGHGE value was -490.29 kg·hm-2 for the whole rice production period, and 18 t·hm-2 mushroom residue applied to the soil was the best way to reduce net greenhouse gas emissions in purple paddy soil.