长期不施磷对稻田温室气体排放的影响

稻田磷肥的“旱重水轻”施肥策略是有效提高磷素利用率、减少磷素流失的有效技术途径,但稻季不施磷对温室气体排放的影响尚不明确。本研究监测了苏州和宜兴两块长期定位试验田中正常施磷与不施磷处理水稻生育期内CH₄和N₂O的排放通量。结果表明: 与正常施磷处理相比,长期不施磷处理均显著促进了稻田CH₄和N₂O排放,其中,苏州试验田CH₄和N₂O排放量分别增加57%和25%,宜兴试验田CH₄和N₂O排放量分别增加221%和70%。长期不施磷使土壤的速效磷、有机酸和可溶性有机碳含量下降,与CH₄排放密切相关,特别是土壤速效磷含量与CH₄排放量呈显著负相关,相关系数r=-0.987。两处试验田不施磷处理的全球增温潜势均大于施磷处理。因此,稻田长期缺磷会对土壤有机酸、可溶性有机碳和速效磷含量产生影响,进而增加稻田CH₄和N₂O的排放。

Effects of long-term fertilization without phosphorus on greenhouse gas emissions from paddy fields

The strategy of few or no-phosphorus fertilization in rice season but more in wheat season can effectively increase phosphorus use efficiency and reduce phosphorus loss through runoff and leaching.It remains unknown whether the lack of phosphorus will affect greenhouse gas emission in the rice season.We monitored the CH₄ and N₂O emission fluxes during the growth period of rice treated with normal phosphorus application(NPK)and no-phosphorus application(NK)in two long-term experimental fields in Suzhou and Yixing.The results showed that long-term no-phosphorus application promoted CH₄ and N₂O emission in both fields.Compared with the NPK treatment,CH₄ and N₂O emissions from the NK treatment significantly increased by 57%and 25%in Suzhou experi-mental field,respectively,while those in Yixing experimental field were also significantly increased by 221%and 70%,respectively.The contents of organic acid,dissolved organic carbon and available phosphorus in soil were reduced under long-term NK treatment,and they were closely related to CH₄ emission.Soil available phosphorus content was significantly negatively correlated with CH₄ emission(r=-0.987).The global warming potential(GWP)was greater in NK treatment than NPK treatment in both fields.Therefore,long-term no-phosphorus application could decrease the contents of organic acid,soluble organic carbon,and available phosphorus in soils,resulting in more CH₄ and N₂O emission in rice field.