减氮施炭对温室膜下滴灌黄瓜土壤呼吸和氮素气态损失的影响

Soil Respiration and N Losses from Greenhouse Cucumber under Mulched Drip Irrigation as Affected by Reduced N Fertilizer Coupled with Biochar Incorporation

为降低温室蔬菜过量施氮的不利影响,明确减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,以不覆膜不施炭(CK)为对照,设置覆膜(M)、覆膜施炭(MB)、覆膜施炭减氮(MBN_(80%))共4个处理,对覆膜条件下减氮施炭处理对黄瓜产量、耗水量、土壤养分动态、土壤呼吸、N_(2)O排放和氨挥发的影响进行探讨。结果表明:与CK相比,M可降低温室膜下滴灌黄瓜全生育期耗水量20.95%,提高水分利用效率41.03%,降低0~20 cm表层土铵态氮48.12%,降低全生育期氨挥发32.35%、N_(2)O排放量14.34%和CO_(2)排放量12.68%(<0.05)。施炭后,与CK相比,MB可降低耗水量28.37%,提高水分利用效率55.60%,降低表层土铵态氮30.0%,提升硝态氮12.37%,有机质56.28%,降低氨挥发36.68%、N_(2)O排放18.64%,但却显著增大了CO_(2)排放4.66%(p<0.05)。同M对比,MB可在M基础上,进一步提升表层土有机质和铵态氮含量,降低氨挥发,但促进了CO_(2)排放。覆膜施炭减氮20%后,与CK相比,MBN_(80%)可增产25.47%,降低耗水量32.43%,提升水分生产率72.67%,降低表层土铵态氮56.33%,增加有机质51.72%,降低氨挥发40.48%、N_(2)O排放20.79%(p<0.05)。CK全生育期全球增温潜势(global warming potential,GWP)和活性氮排放分别为13.57 t·CO_(2)-eq·hm^(-2)和6.54 kg·hm^(-2),M可显著降低GWP(14.15%)和活性氮排放(27.37%);在M基础上施炭,将进一步降低活性氮排放,但导致GWP显著增大;而在MB基础上减氮20%,可同时显著降低GWP和活性氮排放(p<0.05)。与CK相比,MBN80%在通过施炭20 t·hm^(-2),减氮20%条件下,实现增产25.47%,降低耗水量32.43%,增加有机质51.72%,增加收入17.52%,降低活性氮排放35.32%和GWP 2.28%,也可在MB的基础上,进一步实现增产,降低氨挥发,并破解M和MB处理CO_(2)排放增大的问题(p<0.05)。研究揭示了减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,为实现温室蔬菜节水增产固碳减排提供理论依据和技术支撑。

To reduce the negative effects of excessive nitrogen application in greenhouse vegetables and to clarify the characteristics of soil respiration and nitrogen gaseous emission of cucumber under mulched drip irrigation in greenhouse under reduced nitrogen and biochar application conditions.Four treatments were set up:no mulching and no biochar application(CK),mulching(M),mulching with biochar application(MB),and mulching with biochar application and nitrogen reduction(MBN_(80%)).The effects of the reduced nitrogen application and biochar addition treatment on cucumber yield,water consumption,soil nutrient dynamics,soil respiration,N_(2)O emissions,and ammonia volatilization were explored.The results showed that compared to the CK treatment,the M treatment reduced water consumption by 20.95% throughout the entire cucumber growth period,increased water use efficiency by 41.03%,decreased ammonium nitrogen content in the top 0-20 cm soil layer by 48.12%,and reduced ammonia volatilization by 32.35%,N_(2)O emissions by 14.34%,and CO_(2) emissions by 12.68%(p<0.05).After biochar addition,compared to the CK treatment,the MB treatment reduced water consumption by 28.37%,increased water use efficiency by 55.60%,decreased ammonium nitrogen content in the topsoil by30.0%,increased nitrate nitrogen content by 12.37%,increased soil organic matter content by 56.28%,decreased ammonia volatilization by 36.68%,and reduced N_(2)O emissions by 18.64%,but significantly increased CO_(2) emissions by 4.66%(p<0.05).Compared to the M treatment,the MB treatment further increased the content of soil organic matter and ammonium nitrogen in the topsoil,reduced ammonia volatilization,but promoted CO_(2) emissions.After reducing nitrogen application by20% in the MB treatment,compared to the CK treatment,the MBN_(80%) treatment increased yield by 25.47%,reduced water consumption by 32.43%,increased water productivity by 72.67%,decreased ammonium nitrogen content in the topsoil by56.33%,increased soil organic matter content by 51.72%,reduced ammonia volatilization by 40.48%,and reduced N_(2)O emissions by 20.79%(p<0.05).The global warming potential(global warming potential,GWP) and active nitrogen emissions during the entire growth period were 13.57 t·CO_(2)-eq·hm^(-2) and 6.54 kg·hm^(-2),respectively,in the CK treatment.The M treatment significantly reduced GWP(by 14.15%) and active nitrogen emissions(by 27.37%).Adding biochar on the basis of the M treatment further reduced active nitrogen emissions but significantly increased GWP.However,reducing nitrogen application by 20% on the basis of the MB treatment significantly reduced both GWP and active nitrogen emissions(p<0.05).Compared to the CK treatment,the MBN_(80%) treatment achieved a 25.47% increase in yield,a 32.43% reduction in water consumption,a 51.72% increase in soil organic matter content,a 17.52% increase in income,a 35.32% reduction in active nitrogen emissions,and a 2.28% reduction in GWP,with the addition of 20 t·hm^(-2) of biochar and a 20% reduction in nitrogen application.It also further increased yield,reduced ammonia volatilization,and addressed the issue of increased CO_(2) emissions in the M and MB treatments(p<0.05).This study revealed the characteristics of soil respiration and nitrogen gas emissions under the conditions of reduced nitrogen application and biochar addition in a greenhouse cucumber cultivation system,providing a theoretical basis and technical support for water-saving and yield-increasing,carbon sequestration,and emission reduction in greenhouse vegetable production.