摘要:绿肥压青还田是调控现代集约化稻田土壤逆境的重要手段，为评估绿肥压青下粉垄耕作对稻田土壤微生物量碳和土壤有机碳累积矿化量的影响，设置早稻粉垄耕作与常规耕作2种耕作模式，不施肥和同等肥力条件下施化肥、单倍绿肥配施化肥和双倍绿肥配施化肥4种施肥处理，晚稻免耕常规施用化肥，开展双季稻周年大田应用试验。结果表明：单倍绿肥压青下，粉垄耕作能提高稻田土壤微生物量碳含量，可达常规耕作的2倍，能有效增加微生物对土壤碳素的利用率。增加绿肥压青量会提高粉垄耕作稻田土壤有机碳累积矿化量和矿化潜力，与施用化肥相比，单倍绿肥压青下早晚稻分别增加1.6%~32.8%和0.6%~16.6%，双倍绿肥压青下分别增加58.6%~70.9%和29.6%~38.4%。粉垄单倍绿肥压青会降低免耕晚稻齐穗期、收获期土壤呼吸强度，较常规耕作分别降低33.4%和38.7%，较粉垄耕作其他处理降低8.5%~31.4%。单倍绿肥压青下粉垄稻田土壤代谢商较常规耕作累积降低65.5%，与常耕相比，粉垄双倍绿肥压青和粉垄单一化肥的土壤代谢商分别累积增加20.3%和159.2%，粉垄双倍绿肥压青可有效缓解土壤代谢商的提升。微生物量碳含量与有机碳矿化激发效应呈负相关，绿肥压青还田下相关系数达0.44；累积矿化量和代谢商呈极显著正相关，粉垄耕作下相关系数达0.59。可见，绿肥粉垄耦合的模式可作为一种增加稻田土壤微生物量碳含量、减少部分生育时期土壤呼吸强度，增强土壤碳库稳定性及碳固持的重要调控技术措施。
关键词:粉垄/
绿肥压青/
稻田土壤/
微生物量碳/
有机碳矿化
Abstract:Returning green manure is an important method for controlling soil adversity in modern intensive paddy fields. To evaluate the influence of smash ridging under green manure returning on soil microbial biomass carbon and carbon mineralization in paddy fields, annual field application tests of double-cropping rice were conducted with two tillage modes in early rice (smash ridging and conventional tillage), four fertilization treatments (no fertilizer, and under the same fertility conditions applying chemical fertilizer, single green manure with chemical fertilizer, and double green manure with chemical fertilizer), and chemical fertilizer application to late rice for no-tillage. The results showed that the content of soil microbial biomass carbon under single green manure returning to paddy fields can be up to two times higher than that of conventional tillage, which can effectively increase the utilization rate of soil carbon by microbes. An increase in the amount of green manure increased the soil organic carbon mineralization and mineralization potential in the smash ridging paddy field. Compared with chemical fertilizer application, the cumulative mineralization of soil organic carbon and mineralization potential of early and late rice increased by 1.6%-32.8% and 0.6%-16.6%, respectively, under single green manure returning, and 58.6%-70.9% and 29.6%-38.4%, respectively, under double green manure returning. Soil respiration intensity of late rice during no-tillage at the full heading and harvest stages was reduced by 33.4% and 38.7%, respectively, compared with conventional tillage; and reduced by 8.5%-31.4% compared with the other smash ridging treatments. The metabolic quotient in rice soil with smash ridging under single green manure returning decreased by 65.5% compared with conventional tillage. Compared with conventional tillage, smash ridging under double green manure returning and under chemical fertilizer increased by 20.3% and 159.2%, respectively; smash ridging under double green manure returning can effectively alleviate the increase in the soil metabolic quotient. There was a negative correlation between the content of microbial biomass carbon and the priming effect of organic carbon mineralization, with a correlation coefficient of 0.44 under green manure returing. There was a significant positive correlation between cumulative mineralization and the metabolic quotient, with a correlation coefficient of 0.59 under smash ridging. In conclusion, a combination of green manure returning and smash ridging can increase the content of soil microbial biomass carbon in paddy soil, reduces soil respiration intensity during the growth stages, and serves as an important technical measure for the regulation and control of soil stability and carbon fixation.
Key words:Smash ridging/
Green manure returning/
Paddy field soil/
Microbial biomass carbon/
Organic carbon mineralization
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