喷灌和沟灌方式对农田土壤NH3挥发的影响

研究了2016和2017年传统灌溉（沟灌）和节水灌溉（喷灌）方式氨（NH₃）挥发的季节年际动态变化特征及其影响因素.采用通气法进行原位监测，分析了土壤温度、体积含水量、铵态氮（NH₄⁺-N）、硝态氮（NO₃^--N）以及气温降水等因素对NH₃挥发的影响.结果表明，NH₃挥发速率的峰值出现在施用氮肥后1~2周，喷灌有效降低NH₃挥发峰值，喷灌和沟灌的NH₃挥发速率峰值在2016年分别为2.67kg/（hm²·d）和11.11kg/（hm²·d），2017年分别为2.42kg/（hm²·d）和11.73kg/（hm²·d）；马铃薯生长季NH₃挥发存在明显的季节变化，挥发高峰主要发生在7~8月，追肥期高于基肥期.2016~2017年农田土壤NH₃累积挥发量均表现为喷灌<沟灌，与沟灌相比，喷灌分别减少58.15%和43.55%.NH₃挥发速率与土壤温度呈显著正相关（P<0.05），与体积含水量、NH₄⁺-N、NO₃^--N浓度呈极显著正相关（P<0.01）.

Effects of ammonia volatilization from farmland under sprinkler and furrow irrigation

Seasonal characteristics and influencing factors of ammonia (NH₃) volatilization from farmland under traditional irrigation (furrow irrigation) and water-saving irrigation (sprinkler irrigation) in 2016 and 2017 were studied. Effects of soil temperature, volumetric water content, ammonium nitrogen (NH₄⁺-N), nitrate nitrogen(NO₃^--N), temperature and precipitation on ammonia volatilization were analyzed by in-situ ventilation measurements. The results showed that NH₃ volatilization rate increased up to 1~2 weeks after nitrogen application, with the maximum values of 2.67kg/(hm²·d), 11.11kg/(hm²·d) in 2016 and 2.42kg/(hm²·d), 11.73kg/(hm²·d) in 2017, under furrow irrigation and sprinkler irrigation, respectively. The ammonia volatilization showed obvious seasonal pattern in potato growing season, higher in July-August and higher in top-dressing stage than base fertilizer stage. Accumulative volatilization showed sprinkler irrigation produced less NH₃than furrow irrigation, compared with furrow irrigation, sprinkler irrigation with a decrease of 58.15% and 43.55% in 2016 and 2017, respectively. There was a significant positive correlation between NH₃volatilization rate and soil temperature (P<0.05), and significant positive correlations with volumetric water content, NH₄⁺-N and NO₃^--N concentration (P<0.01).