February 22, 2014 1:00 pm JST

'Dream sand' opens up new possibilities for desert farming

TOKYO -- Panasonic is currently carrying out research on proprietary technology for water-repellent sand, together with Kyoto University, with the aim of commercializing it for farming in deserts in fiscal 2016.     

     The basic aim of the project is to build a layer of sand coated with a water-repellent material on the surface of its grains to block water from passing through it. To accomplish this, the researchers dig in the ground, fill the bottom with water-repellent sand and then cover the sand with soil. As the water does not permeate into the water-repellent sand, water accumulates on top of the sand, which then serves a sort of underground aquifer in the desert.

     Such a structure should also be effective in helping prevent salt damage caused by seawater. Theoretically, if a water-repellent layer of sand were built along a seacoast, it would stop seawater from seeping into the land, much like a pool that lets air in but shuts out water. If a water pump were installed on a farm with the water-repellent sand, it would also be able to circulate the water underground in the farm.

Cooking equipment challenge

But why sand? And what made Panasonic, a major home electronics company, take up the challenge of farming in the first place?

     This project originated with the water-repellent membrane technology that Panasonic developed for its microwave oven and induction heating cooking equipment to make the inside of the machines free from stains. Around 1990, the company created technology that made it possible for a water-repellent compound to be adsorbed thinly on various materials and applied the technology to its home electronics.

     The surface of the materials that needed to be coated was often made of glass. Panasonic's technological strength lies in creating a membrane several nanometers thick that is not easily scraped off, by chemically bonding the water-repellent compound with silica, the raw material of glass. The company eventually started exploring the application of this technology in other areas.

     Silica sand was a promising candidate for use in other areas but researchers at the company did not quite know how to make the best use of it. Norihisa Mino, a processing expert at Panasonic's Advanced Technology Research Laboratories, thought taht silica sand might be useful for farming and asked the Graduate School of Agriculture, Kyoto University to conduct a joint study. He recalled that university researchers were surprised by his sudden proposal to start "a revolution in farming," after he got the idea that the sand could prevent soil salinization after several meetings with them. In April 2010, they began testing silica sand at Kyoto University's farm and about a year later had good prospects of commercializing the system to circulate water accumulated on a layer of water-repellent sand.

     Until now, it has been common practice to use water-holding sheets when tree planting in deserts. But poor permeability hampers the growth of plants in some cases. Panasonic's technology has no such worry because there are several hundred micrometers of gap between sand particles, letting air and gas in and out of the space.

     Water does not permeate the sand layers because of surface tension. Repelled by the water-repellent compound on the surface of each partyicle, water collects on top of the sand layer. "Because the adhesiveness of the water-repellent compound is so strong, the effect could last semipermanently as long as it is under the ground," said a Panasonic official.

     The new circulation system has produced a useful by-product. Because the reused water contains fertilizers, vegetable crop yields using this circulation system have increased by an average of 20-30%. This means that the technology can be used not only in deserts but also in vegetable farming elsewhere.

     Meanwhile, Jcam Agri, a major fertilizer maker, has made efforts to create an environment that better suits crop growing and come up with technology to cover fertilizer grains with a particulate resin membrane about 2mm thick. It has developed what it calls "super fertilizer" that can disperse urea, a nutrient, in small amounts.

     A major enemy of field crops is excess nutrients. If too much fertilizer is given to plants at one time, it hampers their growth. However, it is too much trouble to fertilize every few days and the additional labor increases costs, creating a challenge for many farmers.

     Because of the extra step to cover the surface of fertilizer, Jcam Agri's technology pushes up the price of the fertilizer by about 20%, but the effect of plants absorbing optimal amounts of fertilizer could last up to one year. The company is now aiming to sell the innovative fertilizer to large-scale farmers in Indonesia and other Asian countries.