Plants or crops form part of the entire carbon cycle. Growing almost any plant is the same as practicing small-scale carbon sequestration. This is because plants use the air's carbon dioxide (CO2) during photosynthesis.
When the plants die, their carbon-based structure begins to decay. As a result, some CO2 is released into the air, and some is trapped underground. Grasses and other crops quickly draw down CO2 from the air, but they also tend to release it fast when decomposing.
However, plant residues are a valuable resource of organic matter and humus. We, in BTU, conducted a series of scientific trials to study how to accelerate the decomposition of plant residues to improve soil fertility, and keep the carbon stock in the soil.
Biologicals for managing the decomposition of plant residues
ECOSTERN® is the biological destructor, the concentrated preparation specially developed for decomposition of after-harvesting residues of corn, sunflower and other agricultural crops, improvement of soil and prevention of its degradation. It contains life cells of bacteria Bacillus subtilis, Agrobacterium, Enterococcus and fungi Trichoderma lignorum and Trichoderma viride. The total number of viable cells 2.5x109 CFU/cm3. These microorganisms activate the vital soil processes of effective decomposition of crop residues, enrichment of organic matter and available elements of plant nutrition and neutralization of allelochemicals.
Does the biodestructor affect organic residues? May advertising the preparation be just a marketing ploy?
To determine the activity of Ecostern® as a biodestructor, a laboratory experiment was conducted: for a month (30 days), cellulose plates were kept in contact with soil treated with Ecostern®. The control was the soil without treatment with biological preparations. The results of the experiment show that the activity of cellulose destruction in contact with the soil treated with Ecostern® doubles – from 25 to 54% (Table 1). The proportion of Ecostern exposure to cellulose in Variant 2 was 53%, and the soil microflora – 47%. So, the activity of the preparation has been proven.
Table 1. Trial result
Will the application of Ecostern® contribute to increasing carbon dioxide emissions?
Increasing the concentration of greenhouse gases, including carbon dioxide, in the planet’s atmosphere is now a severe environmental problem. At the same time, the final product of the decomposition of organic substances in the soil is carbon dioxide, water, and other inorganic compounds. Therefore, the intensity of carbon dioxide released during composting soil with Ecostern is an essential indicator of the environmental feasibility of its use. The change in the intensity of respiration of gray forest soil (i.e., the release of carbon dioxide) due to its contact with the biodestructor Ecostern® was determined in an experiment that provided a constant temperature (25° C) and soil moisture. For 30 days, four substrates were observed to release carbon dioxide:
1 – soil without treatment with the biopreparations;
2 - soil + Ecostern®;
3 - soil + corn stalks;
4 - soil + corn stalks + Ecostern®.
Table 3. Change in the intensity of respiration of gray forest soil after adding corn stalks and the biodestructor Ecostern in the laboratory experiment.
The value of CO2 emissions during composting in the soil variant was 2.2–109.5 mg/kg, and in the soil + Ecostern® variant – 2.2–107.8 mg/kg of soil per day (Table 2). The highest values in both cases were obtained in the first three days, followed by a smooth decrease. There was no significant increase in the intensity of respiration when Ecostern® was added to the soil. In the soil + corn stalks variant, absolute values varied from 94.1 to 598.9 CO2 mg/kg per day, and in the case of adding the destructor – 97.4–596.8 mg/kg of soil per day (Table 3). The maximum value was from the fifth to the eighth day, followed by a gradual decrease.So, the results of the experiment showed that the action of the destructor Ecostern® developed by BTU did not cause a sharp increase in the release of carbon dioxide into the atmosphere. The preparation is environmentally friendly.
Is soil humus lost due to the acceleration of mineralization processes under the action of Ecostern®?
After completing the experiment with respiration, which lasted 30 days, the content of total humus and carbon of labile organic compounds was determined in the soil. According to the results of the analysis, no humus losses were found in the soil treated with the destructor, but a weak trend towards an increase in total humus was observed (Table 4). Obviously, this effect is due to the transformation of small and already partially destroyed plant residues that were present in the soil by active organisms of Ecostern®. The content of labile organic compounds, which is the first reserve of nutrients for plants, in the composition of humus remained almost constant. During composting of a mixture of soil and corn stalks, the amount of humus substances from the use of the destructor practically did not change. Obviously, the action of the destructor in this case was aimed at the mineralization of large plant residues and the duration of action of destructive organisms was insufficient for the formation of humus substances. This is confirmed by a clear trend towards an increase in labile organic compounds in humus. When composting with the destructor, their number increased by 9.7 % (relative), compared to the variant without the destructor.
Table 4. Content of humus substances in the substrates after composting with the destructor Ecostern:
WHAT IS IN THE RESULT?
Thus, the decomposition of cellulose in the soil is twice as fast with the applying Ecostern® as without it. The preparation is environmentally friendly and does not emit carbon dioxide into the atmosphere. At the same time, soil humus is not lost; on the contrary, it tends to grow.
Svitlana Korsun, Head of the Laboratory for Agrochemical Research