膜孔灌条件下不同氮肥施用后的转化特性研究

Study on the Transformation Characteristics of Different Nitrogen Fertilizer under Film Hole Irrigation

通过室内入渗试验,研究了膜孔灌条件下不同氮肥的转化特性。结果表明,施入铵态氮肥后土壤铵态氮含量在膜孔中心垂向表层0～5.5 cm内变化,再分布15 d土壤铵态氮损失了68%,再分布20 d铵态氮基本完全转化;随再分布时间的延长,硝态氮的含量在土壤表层10 cm范围内逐渐增加,在10 cm以下,硝态氮的含量7 d前先增大再减小,7 d后一直增大。施入硝态氮肥后,硝态氮含量7 d内变化很小,7～10 d内明显减少,10 d以后减少缓慢。施入尿素后,土壤中铵态氮在5 d后达到峰值,20 d后下降至土壤的本底值;而土壤硝态氮一直平稳升高,于施肥20 d后达到最大值;土壤铵态氮含量和硝态氮含量均沿着远离膜孔中心的方向逐渐减小。

Based on lab experiment ,transformation characteristics of nitrogen under film hole single point infil-tration with different nitrogen fertilizer were researched .Results showed that the transformation laws of nitrogen un-der different nitrogen fertilizer were different .The NH4＋-N content at the vertical of film hole center changed in the depth of 0-5.5 cm after fertilization with ammonium fertilizer .The NH4＋-N content lost 68%after redistribution of 15 d and it was transformed completely after redistribution of 20 d.With the redistribution time increased ,the con-tent of NO3--N increased in the 10 cm scope of soil surface layer .Below the 10 cm scope of soil surface layer ,the content of NO3--N first increased and then decreased in 7 d and it always increased after 7 d.The content of nitrate fertilizer changed little in 7 d after fertilization with nitrate nitrogen fertilizer ,but it decreased obviously in 7-10 d and it decreased slowly after 10 d.The NH4＋-N content came to the maximum value in 5 d after fertilization of urea and decreased to the background value in 20 days.While the NO3--N content increased all along and came to the maximum value in 20 days after fertilization.The soil NH4＋-N content and NO3--N content under fertilization de-creased with the distance far from the film hole center .The results lay a foundation for study of film hole irrigation fertilizer technique .