采用单点源滴灌试验模拟土壤入渗，并分不同时段施氮肥，灌水施氮肥结束后，在不同时间段和湿润
体不同位置采集土样，并测定土壤中速效氮的含量，分析比对湿润体中不同位置硝态氮与铵态氮的时空分布，结果
表明:滴灌全程施肥，土壤湿润体中高氮区始终分布在滴头附近;滴灌前 1/2 时段施肥，硝态氮含量的最大值
(107． 50 mg·kg
－1 )出现在距滴头水平距离 15 ～20 cm，垂直距离 15 ～30 cm 范围内;后 1/2 时段施肥，高氮区始终
也分布在滴头附近，但含量值表现极高(184． 36 mg·kg
－1 );中间 1/2 时段施肥，硝态氮主要分布在距滴头水平距
离为 15 cm 左右，垂直深度也为 15 cm 左右的土层范围内。随着时间的推移，土壤湿润体中 NO 3
－
－ N 的含量均表
现为到第 5 天前后达到最高值，此后又开始降低;NH 4
+
－ N 在时间上转化速率相对较快，在灌水施肥结束后的第 3
天硝化作用最强，从第 3 天到第 5 天 NH 4
+
－ N 浓度急剧降低。
其他摘要
Using single-point infiltrational simulation，an experiment on different nitrogen application time un-
der drip fertigation was conducted． Soil ammonium and nitrate content in different location was measured at differ-
ent time after drip irrigation． The results showed that the region with high nitrogen content was always near the drip
emitter for fertigation during the whole drip irrigation． Maximum NO 3
－
－ N content occurred at 15 ～25 cm horizon-
tal distance and 15 ～30 cm vertical distance for fertigation during the first half time of drip irrigation． The region
with high nitrogen was always near the drip emitter for fertigation during the second half time of drip irrigation，but
the content is rather high． Maximum NO 3
－
－ N content existed at 15cm horizontal distance and 15 cm vertical dis-
tance for fertigation in the middle half of the time． The peak content of NO 3
－
－ N in wetted soil body occurred on
the 5th day and then became smaller with time． The transforming rate of NH 4
+
－ N was relatively fast，and the ni-
trification was most strong on the third day after irrigation，resulting in the ammonium content decreased sharply
from the third day to the fifth．
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