稻茬-紫云英联合还田对水稻土表层水可溶性碳氮的影响

Effects of co-incorporation of rice stubble and Chinese milk vetch on dissolved carbon and nitrogen in surface water of paddy soil

紫云英是南方稻田广泛种植利用的冬季绿肥,但利用不当可能带来养分流失的风险。研究探讨了稻茬-紫云英联合还田对水稻土表层水可溶性碳氮的影响,旨在为紫云英的合理利用、农业面源污染的科学防控提供理论依据和技术支撑。以江西省最典型的红壤性水稻土和冲积性水稻土为研究对象,布置精准控制水稻盆栽试验,设4个处理:不施用稻茬和紫云英(CK)、紫云英单独还田(MV)、低量稻茬和紫云英联合还田(LSMV)、高量稻茬和紫云英联合还田(HSMV),各处理施用等量化肥。结果表明:在红壤性水稻土上,MV处理表层水中的可溶性有机碳(DOC)、可溶性总氮(DTN)和可溶性有机氮(DON)含量急剧增加,三者最高时分别达到414.3 mg/L(第7 d)、575.4(第3 d)和532.4 mg/L(第3 d),相对于对应时间的CK分别增加了5.9、14.1和35.8倍;但将稻茬与紫云英联合还田,会使表层水的DOC、DTN和DON含量降低至与CK接近的水平。而冲积性水稻土MV处理的DOC、DTN和DON含量相对于CK最高也仅增加了51.9%(第7 d)、25.2%(第7 d)和58.4%(第7 d)。将稻茬与紫云英联合还田还有助于降低两种水稻土表层水中的铵态氮(NH_(4)_(+)-N)含量,LSMV处理可促进NH_(4)_(+)-N向硝态氮(NO_(3)^(-)-N)的转化,而HSMV处理明显抑制了NH_(4)_(+)-N向NO_(3)^(-)-N的转化。综上,在南方稻田将稻茬与紫云英联合还田应加以推广,尤其是在红壤性水稻土上更应采取此项技术措施。

Chinese milk vetch as a winter green manure has been widely planted in paddy fields of south China,however,improper planting pattern will pose nutrient loss risks.In this research,the effects of rice stubble and Chinese milk vetch co-incorporation on dissolved carbon and nitrogen in surface water of paddy field were studied to provide theoretical basis and technical support for Chinese milk vetch usage and agricultural non-point source pollution prevention and control.A pot experiment was conducted with typical red paddy soil and alluvial paddy soil in Jiangxi,and four treatments were set up:no rice stubble and Chinese milk vetch(CK),Chinese milk vetch alone(MV),low rice stubble and Chinese milk vetch co-incorporation(LSMV),high rice stubble and Chinese milk vetch co-incorporation(HSMV)with the same chemical fertilizer application for each treatment.The results showed that MV increased sharply dissolved organic carbon(DOC),dissolved total nitrogen(DTN)and dissolved organic nitrogen(DON)in the surface water under red paddy soil by 414.3(the 7th d),575.4(the 3rd d)and 532.4 mg/L(the 3rd d),which increased by 5.9,14.1 and 35.8 times comparing with CK,respectively.Co-incorporation of rice stubble and Chinese milk vetch reduced DOC,DTN and DON in surface water to a similar level of CK.Comparing with CK,MV increased DOC,DTN and DON under alluvial paddy soil by only 51.9%(the 7th d),25.2%(the 7th d)and 58.4%(the 7th d).Co-incorporation of rice stubble and Chinese milk vetch also decreased ammonium nitrogen(NH_(4)_(+)-N);specially,LSMV promoted the transformation of NH_(4)_(+)-N to nitrate nitrogen(NO_(3)^(-)-N),while HSMV significantly inhibited the transformation of NH_(4)_(+)-N to NO_(3)^(-)-N.In conclusion,co-incorporation of rice stubble and Chinese milk vetch should be promoted in rice fields of south China,especially in red paddy soil.