不同耕作灌溉和有机肥替代下稻田有机碳和氮磷潜在排放特征

Potential emission characterization of organic carbon,nitrogen and phosphorus from paddy fields under different tillage irrigation practice and organic fertilizer substitution

通过盆钵试验研究了不同耕作条件、不同灌溉方式和基肥期有机肥替代对水稻田面水有机碳与氮磷浓度、潜在可排放量及水稻产量的影响。结果表明:1)浅水灌溉相比常规灌溉,在旋耕时各项指标的平均可排放量均呈现不同程度的降低趋势,其中化学需氧量(COD)降低43.43%,可溶性有机碳(DOC)降低43.19%,总氮(TN)降低46.52%,总磷(TP)降低60.34%;而翻耕时稻田田面水的COD、DOC、TN和TP浓度分别降低22.73%、41.58%、31.58%和31.25%。2)翻耕相比旋耕,在常规灌溉时稻田田面水COD、DOC和TP的平均可排放量分别降低16.02%、15.67%和23.71%;在浅水灌溉时稻田田面水COD、DOC和TP的平均可排放量分别降低43.42%、16.81%和13.93%。3)浅水灌溉下有机肥替代氮肥用作基肥的田面水COD、DOC和TP的平均可排放量无显著差异(P>0.05);浅水灌溉相比常规灌溉,在旋耕和翻耕时水稻产量分别减产20.63%和6.88%。总之,浅水灌溉田面水碳、氮、磷排放风险显著低于常规灌溉,翻耕可以有效降低田面水碳、氮、磷排放风险,从稻田田面水防控和产量角度,浅水灌溉并翻耕能够在保证水稻产量的同时有效降低田面水养分流失风险。研究结果可为稻田投入品优化施用和田间水分及养分管理提供技术支撑。

This article studied the effects of different tillage conditions,irrigation methods,and organic fertilizer substitution during the base fertilizer period on the organic carbon and nitrogen phosphorus concentrations,potential emissions,and rice yield in rice field surface water through pot experiments.The results showed that:(1) Compared with conventional irrigation,shallow water irrigation showed varying degrees of reduction in the average emission of various indicators under rotary tillage,including a 43.43% decrease in chemical oxygen demand(COD),a43.19% decrease in dissolved organic carbon(DOC),a 46.52% decrease in total nitrogen(TN),and a 60.34%decrease in total phosphorus(TP).Under plow tillage,the COD,DOC,TN,and TP in the surface water of paddy fields decreased by 22.73%,41.58%,31.58%,and 31.25%,respectively.(2) Compared with rotary tillage,plow tillage reduced the average emission of COD,DOC,and TP in surface water of paddy fields by 16.02%,15.67%,and 23.71%,respectively,during conventional irrigation.The average emission of COD,DOC,and TP in surface water of paddy fields decreased by 43.42%,16.81%,and 13.93%,respectively,during shallow water irrigation.(3)There was no significant difference(P>0.05) in the average possible emission volume(APEV) of COD,DOC,and TP from surface water using organic fertilizer instead of nitrogen fertilizer as base fertilizer under shallow water irrigation.Compared with conventional irrigation,shallow water irrigation reduced rice yield by 20.63% and 6.88%under rotary tillage and plow tillage,respectively.In summary,the carbon,nitrogen,and phosphorus emission risks of shallow water irrigation field surface water are significantly lower than those of conventional irrigation.Plow tillage can effectively reduce the carbon,nitrogen,and phosphorus emission risks of field surface water.From the perspective of rice field surface water control and yield,shallow water irrigation and plow tillage can effectively reduce the risk of field surface water occurrence while ensuring rice yield.The research results can provide technical support for optimizing the application of rice field inputs and managing field water and nutrients.