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为明确洱海北部地区农田氨挥发损失规律及其影响因素,采用密闭室通气法研究了洱海北部地区水稻季不同施氮量对田面水氨挥发损失的影响,同时测定了田面水NH4+-N浓度、NO3--N浓度、pH值等氨挥发影响因素的变化。结果表明:在施入基肥后,氨挥发通量在第3 d达到峰值后呈波动下降趋势,9 d后氨挥发停止,在施入孕穗肥后,氨挥发通量在第1~2 d内到达顶点而后迅速下降,5 d后氨挥发停止;不同施氮水平与各生育期的氨挥发累积量呈极显著正相关(相关系数在0.839以上),不同生育期的氨挥发累积量表现为:基肥>孕穗肥,施氮处理的氨挥发累积量为15.23~55.45 kg hm-2,而氨挥发损失率在11.28%~15.40%之间;田面水NH4+-N浓度到峰值时比氨挥发通量达最大值时早1 d,当NH4+-N浓度小于10 mg L-1后时不利于田面水氨挥发损失;不同施氮量的氨挥发通量和田面水NH4+-N浓度呈极显著正相关(相关系数为0.624),与田面水pH值、NO3--N浓度则无显著相关。因此,施肥后5~9 d内是控制氨挥发损失的关键时期,而施氮量和田面水NH4+-N浓度的变化是决定氨挥发损失量的关键因素之一。
In order to clarify the rule of ammonia volatilization and its influencing factors in farmland in the north of Erhai Lake, the effects of different nitrogen application rates on the ammonia volatilization of farmland in the northern part of Erhai Lake during the paddy field in northern Erhai were studied. Meanwhile, the NH4 + NO3 - N concentration, pH and other factors affecting ammonia volatilization. The results showed that ammonia volatilization flux decreased at the 3rd day after application of basal fertilizer, and ammonia volatilization stopped after 9 days. After application of booting fertilization, the ammonia volatilization flux was within 1 ~ 2 days Reaching the peak and then dropping rapidly. After 5 days, the ammonia volatilization stopped. There was a significant positive correlation between different N levels and ammonia volatilization accumulation in all growth stages (the correlation coefficient was above 0.839). The accumulative amounts of ammonia volatilization in different growth stages showed as follows: Base fertilizer> booting fertilizer, ammonia volatilization was 15.23 ~ 55.45 kg hm-2, while ammonia volatilization loss was between 11.28% ~ 15.40%. NH4 + -N concentration in field water was higher than that of ammonia volatilization At the maximum of 1 d, NH4 + -N concentration was less than 10 mg L-1, which was not conducive to the ammonia volatilization loss of surface water. The ammonia volatilization flux of different N application rates had a significant positive correlation with NH4 + -N concentration in surface water (Correlation coefficient was 0.624), but no significant correlation with pH and NO3 - N concentration in surface water. Therefore, the key period of ammonia volatilization loss control is 5 ~ 9 d after fertilization, and the change of nitrogen application rate and NH4 + -N concentration in field water is one of the key factors to determine the ammonia volatilization loss.