Establishment of soil managements for moisture-nutrients and saline irrigation by drip method in sand fields

从1986-1988年的研究结果来看，总结如下：探讨了滴灌条件下土壤水分和盐分的运动特征，即：(1)大沙田的三维分布特征、(2)裸沙田的二维分布特征和(3)高粱根区一维分布特征。采用渗滤仪对棉花栽培进行了淋滤试验。在0.16和0.18的浸出分数条件下，土壤盐类的浸出率分别为40%和60%。3500ppm盐水灌溉的棉花产量低于非盐水灌溉的一半。探讨了在集中供水和滴灌两种灌溉方式下，利用种植蔬菜的土柱在生长柜中进行水分和盐分的运动。1天内，滴灌法蒸腾活跃期主根区水分利用效率高，盐浓度高。采用^<45>Ca同位素自动射线照相和图像分析方法对实验室砂柱条件下的土壤盐类运动进行了研究。通过这些方法，可以在不取样的情况下定量分析盐类，并在土壤柱中每小时追踪盐的运动。

From the studies during 1986-1988, the results were summarized as follows.1. Movements of moisture and salts under drip irrigation were discussed on the characteristics of (1) three-dimensional distribution in the dare sand field, (2) two-dimensional distribution in the bare sand field and (3) one-dimensional distribution in the root zone of sorghum.2. Leaching experiments on cotton cultivation were carried out using lysimeters in grass-house. The leaching ratios of soil salts showed 40% and 60% under the conditions of leaching fractions of 0.16 and 0.18, respectively. The cotton yields with the saline irrigation of 3,500 ppm decreased below a half of those obtained with non-saline irrigation.3. The movements of moisture and salts were discussed under the conditions of two irrigation methods of concentrated water supply and drip method, using the soil columns planted with vegetables in the growth cabinets. The drip method showed more efficient water use and higher salts concentration in the main root zones during active transpiration stage in a day.4. The methods of auto-radiography using isotope of^<45>Ca and image analysis were applied to the soil salts movement under the conditons of sand columns in the laboratory. It was established by these methods that salts were analyzed quantitatively without soil sampling and salt movements were traced hourly in the soil colomns.