不同施肥措施对黑土土壤水分及保水性的影响

在长期定位试验中,采用中子水分测量仪对其中的4个处理(F1-无肥、F2-中量化肥、F3-高量化肥、F4-高量化肥加有机肥)进行了为期3年的土壤水分监测。结果表明:施肥处理显著影响了土体内的水分变化,影响范围主要是10cm~90cm。深度超过90cm之后,施用高量化肥的处理含水量超过了其它3个处理,施用相对高量的化肥具有明显的保水作用,而施用有机肥则增加了土壤的疏松透气性,因而增加了蒸发。施肥多的两个处理比较于不施肥和施肥少的处理水分的纵向变幅要大。施入了高量化肥的处理,在高产的同时,保存了70cm以下土体的含水量,而施入同样高量化肥配合有机肥的处理,深层的含水量没有单施高量化肥的高。施用化肥降低了土壤水分的蒸发,提高了保水性。施用化肥同时施用有机肥改善了土壤的透气性。施用有机肥的处理具有如下特点:在含水量高的时候,有排水的作用;在含水量适中的情况下,蒸发量最小,有保水的作用。不施肥的处理,在适宜的水分条件及干旱的情况下,蒸发量最大;在土壤含水量较大的情况下,蒸发较慢,相对而言不具有保水及排涝的作用。图5,表2,参13。

Impact of Fertilization Methods on Soil Water and Soil Water Retention

Soil water content of four treatments in a long-term experiment including no fertilizer,medium fertilizer,high fertilizer,and high fertilizer plus organic amendments were measured using neutron water measuring instrument for three years.In addition to field experiment,a lab experiment also was conducted using top soil collected from corresponding plot of four different treatments in the field to determine soil evaporation.The results showed that:Fertilization treatments make a difference on the movement of soil water in the range mainly from 10 cm to 90 cm.A higher level fertilization have a higher water retention,while organic amendments can make soil more mellow and had a high air-permeability,consequently a high evaporation.Two high-level fertilized treatments have wide range vertical changes in water content than lower fertilized treatments or no fertilized treatment.High level chemical fertilizer treatment changed vertically the most.Moreover this treatment saved the water below 70 cm when harvest the highest yield,high chemical fertilizer plus organic amendments treatment did not saved water.Applying of chemical fertilizer decreased soil water evaporation,consequently increased soil water retention,while applying chemical fertilizer plus organic amendments improved soil air-permeability.Applying organic amendments have drainage effects to some extent when soil had higher level water content,have lower evaporation and water retention effect when soil had moderate or high water content.