Mr. Miyashita: We ask specialist institutions to perform component analyses, which are released to the public. Such analyses, however, cost approximately 100,000 yen per sample and take many days to obtain results. Since the mineral components contained in water are essential in hydroponic culture, we needed we needed to measure water constantly. The measurement equipment to provide accurate results immediately is needed. We also needed a simple method to measure the concentration of nitric acid, potassium, and calcium in nutrient solution. So, we used LAQUAtwin to perform measurements and obtained results that correlated highly with those of the analyses performed by specialist institutions. This led me to believe that LAQUAtwin could be used in our factory.

HORIBA: So, you are using LAQUAtwin in your daily management operations?

Mr. Miyashita: We use five types of LAQUAtwin-series equipment to measure pH, sodium ion concentration, nitric acid ion concentration, potassium ion concentration, and calcium ion concentration. Nutrient solution is used in four different processes; we must perform measurements in all these processes every day. Since vegetables absorb nutrients in different amounts in different processes, it is very important to maintain concentrations at a constant level. We also check the concentration of nutrients contained in harvested lettuce daily. Compared to the data in the Ministry of Education, Culture, Sports, Science and Technology’s food database, our lettuce contains three times as much magnesium and 1.3 times as much calcium, which are minerals used to make bones and teeth. Currently, we are working to increase the zinc content, which helps to maintain one's sense of taste as well as the health of the skin and mucous membranes.

HORIBA: Putting such nutrients into lettuce makes it all the more important to control the nutrient solution components?

Mr. Miyashita: Yes. Since the nutrient solution is composed of positive and negative ions, it is possible to increase one type of ions by the same amount of another type of ions you eliminate. For example, if you decrease the amount of potassium ions, the amount of magnesium ions increases. The less sodium ions, the better—so we are also studying how to reduce the amount of sodium ions.