. Scientific Frontline: Plants on Ash Dumps Experience Nutrient Deficiency

Thursday, September 28, 2023

Plants on Ash Dumps Experience Nutrient Deficiency

Scientists studied two ash dumps in the Middle Urals.
Photo Credit: From the personal archive of Anna Betekhtina

Many nutrients, especially nitrogen, are not available to plants on ash dumps, biologists from the Ural Federal University and the Institute of Plant and Animal Ecology of the Ural Branch of the Russian Academy of Sciences (IPAE UB RAS) have found out. Despite the fact that nitrogen accumulates in the soil of ash dumps as a result of overgrowth, its availability to plants is very low. This situation is unique, because usually the nitrogen content in the soil is directly related to nitrogen content in plants. The description of chemical analysis of plants and soils of ash dumps scientists published in the journal "Ecology". 

"Nitrogen is one of the most important elements of plant nutrition, and its availability determines the productivity of plant communities. At various natural sites, a single pattern has been shown: when the nitrogen content in the soil increases, its amount in plants also increases. Such dynamics is described in many works of Russian and foreign scientists. However, our results turned out to be quite different. The results obtained on other natural objects cannot be transferred to technogenic landscapes, such as ash dumps", explains Anna Betekhtina, senior researcher of the Laboratory of Restorative Ecology at UrFU.

An ash dump is a specially equipped area near an industrial plant, most often near a Combined Heat and Power Plant (CHPP), where ash and slag left after coal combustion are collected. Ash and slag waste is an artificial lifeless substrate. However, after a certain period of time, life takes hold and the ash dump gradually becomes overgrown with microorganisms and plants. This process is called "succession".

"Succession, or succession, is the gradual replacement of one plant species by another. Suppose there is a bare lifeless substrate - as in the case of an ash dump. This substrate cannot remain uninhabited for too long. After a short time, first algae, then weeds, then grasses appear on it, and gradually, gradually, after hundreds of years, light coniferous and dark coniferous forests are formed there, which are a zonal type of vegetation," explains Anna Betekhtina.

In order to obtain the necessary data, the scientists studied the composition of soils and plants of two ash dumps located in the Middle Urals. One of them is a young one, 5-8 years old, and it occupies an area of 358 hectares. The second is an old one, 53-56 years old with an area of 125 hectares. To measure the levels of phosphorus and nitrogen in the soil, the scientists carried out a chemical analysis. For this purpose, they took samples of young soils from the ash dumps and measured the phosphorus content in the laboratory using a potentiometer, and the nitrogen content using Kjeldahl combustion method. Using the same method, the biologists determined nitrogen and phosphorus content in the leaves of the plants.

"We chose the young ash dump - as the initial stage of overgrowth. And the old ash dump - as a more mature stage of overgrowth. On the young ash dump, pioneer annuals grew, such as chenopodium, wormwood, buttercup, reed grass, mayweed and others. On the old one, a forest of birch and aspen had already formed, as well as meadow communities where perennial plants such as yarrow, chamaenerion, plantain, etc. grew. Chemical analysis showed that the soils of the young ash dump have little nitrogen, but a lot of phosphorus. And in the old - the content of phosphorus decreased, and nitrogen increased. This pattern is characteristic of soil development on natural substrates - in the process of overgrowth, the amount of carbon and nitrogen in soils will increase, and the amount of mobile phosphate will decrease. However, the analysis of plants made it clear that despite the accumulation of nitrogen in the soil, it is not available to plants", comments Anna Betekhtina.

Scientists will continue to study ash dumps and the plants growing on them. Since plants can consume nutrients with the help of free-living nitrogen-fixing organisms, special bacteria that take nitrogen from the air, the next stage of research will be devoted to the study of free-living nitrogen-fixing organisms.

Funding: The work was supported by the "Priority-2030" program. Geobotanical research and plant analysis were carried out under the state task (No. FEUZ-2023-0023).

Reference: Nitrogen is one of the basic nutritional elements for all living organisms, and its content in soils determines the level of fertility. Nitrogen is most commonly used in the production of fertilizers for use in agriculture. In addition to the agro-industrial sector, nitrogen is also used in medicine, industry, oil and gas, food production and others.

According to the Food and Agriculture Organization of the United Nations, Russia remains the largest exporter of nitrogen fertilizers, accounting for 18% of all shipments. China ranks second (16%). The countries of the European Union together export about 8% of the world's fertilizers. Fourth place is shared by Qatar, Oman, and Saudi Arabia, each accounting for 6% of total exports.

Published in journalEcology (in Russian)

Source/CreditUral Federal University | Sergey Lukyanchenko

Reference Number: bio092823_01

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