Influence of the membranes on water retention in saturated homogeneous sand columns

Abstract

In arid and semi-arid regions, water is a major limited factor to vegetation and environment. To study the influence of membranes on water retention, three homogeneous sand columns with membranes were installed. Keep the height of free water at Scm above the soil surface of those columns for 3 hours. Experiments results showed that membranes have strong influence on water retention in saturated sand columns. The membranes could slower water movements through the columns and reduce water dynamic parameters such as hydraulic conductivity. So it has an important role in water retention in sand soils, especially in arid and semi-arid regions.

Increasing Vegetable Production on Transformed Sand to Retain Twice the Soil Water Holding Capacity in Plant Root Zone

“…Irrigated vegetables grown on SWRT membrane improved soils irrigated to maintain a range of 15-18% volumetric water content (VWC), enabling vegetable plants to avoid plant water deficits producing at least 20% greater yields of higher quality fruit than controls. However, when soil VWC exceeded 18% soil water solutions containing dissolved nutrients will most likely be lost via gravitational macro pore flow to soil depths below the dominant rooting zone [1][2][3]. Plant wilting occurred when VWC dropped below 10% during daytime hours, resulting in projected accumulations of toxic metabolites contributing to lower yields by annual plants [16].…”

“…shallower than the deeper membranes as outlined in Figure 1. Soil depth of the deepest membrane is identified by capillary rise in sand filled columns described by [1]. These same capillary rise measurements can be completed by farmers in any machine shed.…”

“…When soil moisture is maintained within a range of 15-18% VWC, both pepper and cucumber plants avoided plant water deficits producing much higher yields of quality fruit. When soil moisture exceeded 20%, note two times in Figures 6A and 6B, soil water solutions containing dissolved nutrients were lost via gravitational macropore flow to soil depths below the main rooting zone [1,15,3]. Visual plant wilting symptoms were evident during daylight hours on both plant cultivars when VWC dropped below 10%.…”

“…Competition for and cost of irrigation water are also discouraging current vegetable producers to expand onto sand and loamy sand soils. A new auto-regulating soil water content technology offers the potential for expanding production onto sand soils while using less water than current practices [1] identified how impermeable water retainers, strategically placed in sand columns, retained twice as much water compared to naturally drained sand columns. SALUS models of the soil-plant-atmosphere, programmed to maintain constant optimal soil water in plant root zones, predicted enormous plant production increases [2].…”