南方双季稻区冬闲期绿肥对田间养分固持和减排的影响

Effects of green manure on field nutrient retention and emission reduction in double cropping rice area of southern China during winter fallow period

【目的】探究南方双季稻区冬闲期不同绿肥品种混播对稻田氮磷钾养分固持减排效果,为有效降低冬闲期稻田中养分的流失,改善农业生态环境提供参考依据。【方法】2019—2020年,采用田间小区试验,设计紫云英、油菜、黑麦草和肥田萝卜等常见绿肥单播或混播8个绿肥处理,以自然生草为对照处理,监测双季稻区冬闲期间水体氮磷钾养分流失量,测定绿肥总生物量和植株体中总碳氮磷钾含量以及土壤中养分含量。【结果】冬闲期种植绿肥的处理中稻田氮磷钾养分固持和减排效果明显优于对照处理,种植绿肥处理水体中总氮、总磷和总钾流失量较对照处理降幅分别为27.7%~47.6%、14.3%~65.5%和9.8%~93.6%,其中种植黑麦草的处理中总氮磷钾流失量显著低于其他处理(P<0.05,下同);种植绿肥处理的植株总生物量较对照处理增加46.9%~378.7%,植株体中总碳、总氮、总磷和总钾含量较对照处理分别增加67.9%~377.1%、55.4%~2613.6%、68.0%~557.8%和100.0%~664.5%,其中种植紫云英的处理中总碳氮磷钾含量显著高于其他处理;相比对照处理,冬闲期种植绿肥处理中土壤活性有机质含量、缓效钾含量和阳离子交换量分别增加21.3%~29.8%、1.6%~5.7%和1.3%~8.2%,土壤有效磷和速效钾含量分别降低2.3%~17.0%和3.7%~30.1%。【结论】南方双季稻区冬闲期种植绿肥对田间养分固持减排效果显著,其中紫云英和黑麦草混播(紫云英∶黑麦草=4∶6)处理对降低水体总磷钾流失量、提高植株体中总碳磷钾固持量的效果最佳。

【Objective】To explore the effects of mixed sowing of different green manure varieties on nitrogen,phos-phorus and potassium nutrient retention and emission reduction in double cropping rice areas in southern China during winter fallow period,so as to provide reference basis for effectively reducing the loss of nutrients in paddy fields during the winter fallow period and improving the agricultural ecological environment.【Method】From 2019 to 2020,a plot experiment was conducted to design 8 treatments of single or mixed sowing of common green manure,such as Astragalus sinicus L.,Brassica napus L.,Lolium perenne L.and Raphanus sativus L.in the fertile field,with natural grass as blank control,to monitor the loss of nitrogen,phosphorus and potassium nutrients in water,and to detect the total biomass of green manure,total carbon,nitrogen,phosphorus and potassium contents of plants and the corresponding nutrient contents in soil during winter fallow period in double cropping rice area.【Result】The overall effect of nitrogen,phosphorus and potassium nutrient retention and emission reduction in paddy field with green manure treatment was better than that of the control treatment(natural grass).The loss of total nitrogen,phosphorus and potassium contents in the treatment of plan-ting green manure decreased by 27.7%-47.6%,14.3%-65.5%and 9.8%-93.6%respectively compared with the control treatment.The total nutrient loss of L.perenne treatments was significantly lower than that of other treatments(P<0.05,the same below).Compared with the control,the total biomass in the treatment of planting green manure increased by 46.9%-378.7%,the contents of total carbon,nitrogen,phosphorus and potassium contents in the treatment of planting green manure increased by 67.9%-377.1%,55.4%-2613.6%,68.0%-557.8%and 100.0%-664.5%respectively.The total nutrient retention of A.sinicus treatments was significantly higher than that of other treatments.Compared with control,the con-tents of soil active organic matter,slow-release potassium and cation exchange capacity in the treatment of planting green manure increased by 21.3%-29.8%,1.6%-5.7%and 1.3%-8.2%respectively,and the contents of soil available phosphorus and available potassium decreased by 2.3%-17.0%and 3.7%-30.1%respectively.【Conclusion】Planting green manure in double cropping rice areas in southern China during winter fallow period has a significant effect on nutrient retention and emission reduction in the field.The mixed planting of A.sinicus and L.perenne(A.sinicus∶L.perenne=4∶6)has the best effect on reducing the loss of total phosphorus and potassium in water and improving the retention of total carbon,phos-phorus and potassium in plants.