Growing plants on polymer film cuts water and fertilizer use

Working with a startup, Japanese chemical company Denka has commercialized a new cultivation system that eliminates the need for soil.

The method involves growing plants on a polymer film containing nutrients, and offers the advantage of greatly reducing the volume of water and fertilizer used, compared to conventional hydroponics. In Japan, the method has already been adopted for growing tomatoes, and in the future Denka aims to develop it overseas in locations where there are problems with soil or water.

“This is the most delicious tomato I’ve ever eaten,” said one person after trying a tomato grown using Denka’s system in June in a farming region of Kanagawa Prefecture.

Denka, formerly known as Denki Kagaku Kogyo, was founded in 1915 as a fertilizer producer. Agribusiness, including fertilizers, remains one of its core operations. As chemical companies both at home and abroad have expanded fertilizer production to meet demand accompanying global population growth, price competition has become intense and the influx of inexpensive imports has grown. “Our aim was to plant the seeds of new businesses using cutting-edge agricultural methods,” explained a Denka official.

Denka teamed up with Mebiol, a venture company launched by Waseda University, to develop a cultivation system using Mebiol’s polymer film. Sales began last November.

Crops are grown by placing a water-stopping sheet and nonwoven cloth on the ground and spreading the polymer film on top of that. For fertilizer, humic acid, which is the primary component of compost and stimulates the action of the roots, is used. From a special tube installed under the film, a culture solution including the liquid fertilizer flows into the film. Compared to conventional hydroponics, this method reduces the quantity of both water and fertilizer needed by more than half. It can also boost harvests by around 10%.

Cutting diseases

One major challenge in agriculture is crop diseases caused by viruses and bacteria. Mebiol’s film was also developed for medical uses and passes water and nutrients, while stopping bacteria and the like that could damage the crops. There is also no risk of bacteria entering from the soil, which reduces the amount of agrochemicals that are needed.

Unlike leaf crops like lettuce, a moderate degree of “water stress” is necessary to make fruit-bearing crops like tomatoes taste good. In an environment with little water, “the plant tries to protect itself, and in so doing stockpiles nutrients,” the official explained, and the result is fruits and vegetables with copious amounts of sugar and amino acids.

Denka’s system makes it easier to apply moderate water stress compared to hydroponics, in which the plant’s roots are always in water. On the other hand, because there is a risk that the plant will dry out if there is too little water, liquid fertilizer also flows from a tube installed on top of the film, thereby managing proper quantities.

At present, this system has been used for a variety of tomatoes, particularly fruit tomatoes with high sugar content. The system can also be applied to strawberries and melons.

Besides farmers, Denka is selling the system to companies looking to get into agribusiness. The company supplies materials and fertilizer, and provides advice on cultivation management. It is targeting around 1 billion yen ($9.9 million) in annual domestic sales of the system in four to five years.

Eventually, the company aims to introduce the system in overseas markets as well. Because the method enables crop cultivation even without soil and with only small quantities of water, crops could be grown even in arid regions and in areas plagued by such problems as salty air and contaminated soil. Denka is contemplating development of the business in various places, including China, the U.S. and the Middle East.

Japan’s agribusiness market was worth 55 billion yen in 2015, according to market research company Fuji Keizai. That is forecast to grow 10% to 61 billion yen in 2020. In particular, solution cultivation-related farms and other plant factories are expected to grow 83%, from 8 billion yen to 14.7 billion yen, and many companies are looking to get into the business.

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