灌溉与非灌溉条件下黄淮冬麦区不同追氮时期农田土壤氨挥发损失研究

Ammonia volatilization loss in Huang Huai winter wheat cultivation areas under irrigated and rainfed conditions

采用通气法研究了灌溉与非灌溉条件下黄淮冬麦区农田氨挥发损失。结果表明,非灌溉条件下,麦田追肥氮的氨挥发主要发生在施肥后的5～25 d内,追氮时期由起身期(SE,GS30)推迟到拔节期(JT,GS32),追肥氮的氨挥发速率峰值增大且出现时间提前;继续推迟至孕穗期(BT,GS41),氨挥发速率峰值减小。SE、JT和BT三个追氮时期的氨挥发损失量分别占追肥氮的24.84%～25.32%、25.42%～25.50%和14.77%～16.62%。灌溉(60 mm)条件,不论何时追氮,麦田追肥氮氨挥发速率均变化较小,氨挥发损失量在N 0.40～0.55 kg/hm2之间,仅占追肥氮的0.36%～0.49%。非灌溉条件,氨挥发速率与0—10 cm土层土壤铵态氮浓度呈极显著的正相关关系;灌溉条件,氨挥发速率与10—20 cm土壤浓度呈极显著的正相关关系。土壤温度和降水是影响氨挥发的重要因素。此外,氨挥发还与农田土壤表面的通气状况有关,多穗型小麦品种更有利于减少麦田氨挥发的损失。

A venting method was adopted to determine the effect of nitrogen topdressing stages on ammonia volatilization（AV） from topdressing fertilization in irrigated and rainfed wheat fields.The results show that under rainfed conditions,the AV from topdressing fertilization in wheat fields is mainly in the period from 5 to 25 days after the fertilization.With the delay of nitrogen topdressing stage from the pseudo stem erection stage（SE,GS30） to the jointing stage（JT,GS32）,the peak value of the AV rate is increased and the occurrence time of the peak is ahead.With the delay of nitrogen topdressing stage to the booting（BT,GS41）,the peak value of the AV rate is reduced.The rates of AV loss are 24.84%-25.32%,25.42%-25.50% and 14.77%-16.62% in the SE,JT and BT treatments,respectively.Under 60 mm irrigation amount,the nitrogen fertilization stage has less effect on the AV,the AV rates from the topdressing fertilization are not changed significantly,and the N loss from the accumulated AV is N 0.40 to 0.55 kg/ha,only accounting for 0.36% to 0.49% of topdressing N.Under the rainfed conditions,there is a significant positive correlation between 0-10 cm layer soil NH＋4-N concentration and the AV rate,and under irrigated conditions there is a significant positive correlation between 10-20 cm layer soil NH＋4-N concentration and the AV rate.Soil temperature and rainfall are the important influence factors of AV.In addition,AV is connected with aeration status of field soil surface.Multiple spike type wheat is helpful to reduce wheat field AV loss.