Research on solar desalination system and water-saving farming methods for small-scale farmers

Abstract

We are proposing a water-saving farming method for small-scale farmers using a solar-powered desalination system and purified freshwater. Desalination plants generally use reverse osmosis membranes, disinfection chemical materials, and consume large amounts of fossil fuels. The solar desalination system we have developed so far is a low-cost, repeatable system that uses the same vacuum heat-absorbing tubes and flat plate heat-absorbers used in solar water heaters. We consider that small-scale farmers are also less burdened by using solar heat, a renewable energy source. The result of calculating the energy conversion efficiency from the measurement of evaporation was 30 ~ 46%. Next, water-saving agriculture is so crucial for the efficient use of purified freshwater for agriculture. And the water-saving farming method was based on the stone mulch farming, laying bricks on top of root-prevention sheets and using pit tillage. The stone-mulch farming method reduces evaporation of water, and the root-prevention sheeting relatively reduces competition from weeds. Fertilizer and soil can be added to a locally tilled area to provide intensive nutrition. It also allows for continuous cultivation without removing stones and prevents soil drying and deterioration caused by full tillage. Although in Japan, the experiment of cultivating onions in the open fields using this farming method resulted in nearly double the harvest compared to the conventional method using a tiller. In the future, we will develop the technology for small-scale farmers, such as family farmers, can engage in production by also combining it with drip irrigation.