Scientists of the REC "Botanical Garden" and the youth laboratory of physical and chemical methods for studying plants of Belgorod State University are working on the problem of utilizing citrogypsum, an unused by-product in the production of citric acid, reports official website of the Belgorod State National Research University (NRU "BelSU").
Research is carried out within the framework of the world-class REC project "Innovative solutions in the agro-industrial complex" "Creation of a full cycle system of scientific methodology for the introduction of valuable agricultural and ornamental crops based on breeding and genetic research."
To date, there are several ways to obtain citric acid, the most common is synthesis through chemical reactions. In the process, a large amount of citrogypsum is formed. The substance is not used in production and is stored in large quantities at landfills. The volume of one such landfill in Belgorod is about 500 thousand tons. In this regard, on the one hand, the problem of waste disposal arises, and on the other hand, the reduction of the technogenic load.
The project participants set the task of understanding what citrogypsum can be used for, so as not to store idle in huge volumes. University scientists expect to return some of the elements to the natural chain by including plants in it.
The idea of the project is to convert phosphorus and sulfur into accessible and easily digestible forms. Plants grown on citro- and phosphogypsum accumulate these substances. In the future, compost or organic fertilizer can be made from plant parts. The resulting humus is easy to dispose of or use to feed agricultural and ornamental crops.
To study the development of plants on soil with an admixture of citrogypsum and phosphogypsum, an experimental "garden" with a total area of 100 square meters was set up. Three sites were placed on the site - with citrogypsum, phosphogypsum and chernozem. The latter is necessary to control the experiment and understand how plants grow on fertile soil, and how - on the experimental substrate. A separate experimental group of plants are agricultural crops: soybean, corn and mustard. They are planned to be used as green manure (fertilizers of plant origin) for use in the agricultural sector.
Studies have shown that, compared with the control group, in plants grown on citrogypsum, the sulfur content increases two times, the zinc content three times and calcium five times, and the content of other macro- and trace elements with the exception of potassium and phosphorus, which plants lack. Cultivation of the same plants on phosphogypsum showed an increase in tissues of all nutrients from 20 to 10%.
Thus, soybean on phosphogypsum accumulates sulfur 2,5 times better than when grown on citrogypsum. However, this significantly worsens the processes of photosynthesis, which scientists studied using non-invasive methods for determining the content of chlorophyll and flavonoids in the leaf epidermis. Therefore, the task of the project participants is to select the widest possible range of plants that will effectively extract the necessary elements from the substrates in anthropogenically transformed areas. The next step could be the development of a technology for obtaining sublimated forms of "green" fertilizers.
The experiment should last several years, since the accumulative properties must be observed in dynamics.