More food needs to be produced on soils located near consumer markets globally. This mandate requires innovative hydropedologic technology that produces more food with less water. Since most of the farmland is currently under production or has been badly eroded, more of the 26% land area occupied by highly permeable sand soils needs to be converted to sustainable agricultural production. Opportunities for reducing groundwater pollution in sands require additional exploration of innovative hydropedological mechanisms improving the retention of gravitational water in the root zone. Following model testing of a revolutionary innovative technology, a greenhouse lysimeter was constructed and the sand soil equipped with spatially distributed impermeable subsurface soil water retaining membranes. The entire lysimeter volume of sand was equipped with multiple soil water probes, soil solution vacuum extraction probes and minirhizotrons to best quantify soil water, nutrient, and root distributions within the plant rhizosphere. This report identifies improvements in soil water holding capacities in plant root zones and water bypass rates of membranes during excess irrigation. At the onset, HYDRUS-2D modeling identified optimally configured aspect ratios for soil water retention membranes, spatially distributed to retain uniform maximum volumetric soil water contents for establishing higher field capacity of water coupled with optimal soil aeration in the root zones of plants. Furthermore, these membrane configurations needed to be engineered to optimal drainage during excess rainfall or supplemental irrigation rates greater than 9.4 cm per day, avoiding saturation within and above these water retention membranes. This lysimeter design enabled us to quantify accelerated water conductivity within the soil and plant root zone located above these membranes installed at multiple depths. Lower soil water matric potential in the capillary fringe above these membranes doubled the water holding capacity, increased maize production by 240%, increasing water use efficiency by 77% while increasing shoot to root ratios 30%. This new soil water retention technology (SWRT) can be installed manually in very small gardens and equipment is being developed for installing up to 5 hectares daily at reasonable prices with return on investment of one year for vegetable crops and up to 5 years for maize and soybean crop rotations. We believe this new SWRT conversion of sand soils will develop sustainable agricultural production of maize that approaches 20 metric tons of grain per hectare for each of one to three crops annually.
Prof. Dr. Bilal BİLGİN