滴灌施肥条件下土壤水分和硝态氮的分布规律

用硝态氮含量为258 mg/L的肥料溶液在土上进行滴灌施肥试验,研究不同滴头流量(2,4,6L/h)、不同灌水施肥量(8,16,24 L)条件下,水分和硝态氮在土中的运移分布规律。结果表明,灌水施肥量为8 L时,随滴头流量增大,滴头周围地表积水区半径增大,水分径向运移距离增大、竖向入渗水量减小;当滴头流量为2 L/h时,随灌水施肥量增大,水分径向和竖向运移距离增大,径向运移距离增大幅度较竖向明显。滴灌施肥条件下硝态氮在土壤中的运移受对流作用控制;湿润体内土壤硝态氮含量随距滴头径向距离增大而减小,随距滴头竖向距离增大而增大,在竖向湿润锋附近有硝态氮累积现象;随滴头流量增大,硝态氮在土壤中的径向运移距离增大,0~25 cm土层滴头径向25 cm范围土壤硝态氮平均含量增大;随灌水施肥量增大,滴头径向15 cm范围0~15 cm土层土壤硝态氮含量增大1、7.5~30 cm土层硝态氮含量减小,过度增大灌水施肥量会导致土壤湿润锋附近硝态氮淋溶下渗。

Distribution of Soil Water and Nitrate in Lou Soil under Drip Fertigation

Put some quantity of NH₄NO₃ fertilizer in water,confect fertilizer liquor,the NO₃^--N density is 258 mg/L,use the fertilizer liquor to do fertigation test,the distributions of water and NO₃^--N in Lou soil were investigated under the controlled condition such as dripping end rate at 2,4,6 L/h and fertigation volume at 8,16,24 L/h.The results showed that as fertigation volume was 8 L/h,with dripping rate increased,surface catchment radius around tip increased and more water trans-ported horizontally,while less water transported vertically.As dripping rate was 2 L/h,with irrigation volume increased,dripped water transporting to horizontal and vertical direction are all increased.But water increased more in horizontal direction than in vertical direction.NO₃^--N moving belongs to "convectio ncontrol" style;as the level distance increased,NO₃^--N density decreased,as the soil layer depth increased, NO₃^--N density increased firstly,and then reduced later,cumulate NO₃^--N emerged round soil wetness peak in vertical;dripping end flow increased,NO₃^--N moving distance in horizontal in soil increased,NO₃^--N density increased in level of 25 cm and 0-25 cm in vertical in soil;irrigation and fertilization volume increased,NO₃^--N density increased in the scope of 15cm in level and 0-15 cm in vertical,decreased in the scope of 30 cm in level and 17.5~30 cm in vertical, fertigation increased more NO₃^--N around soil wetness peak would shower and leakage down.