The effect of different biopreparations on soil physical properties and CO2 emissions when growing winter wheat and oilseed rape

Abstract. The introduction of innovative technologies in agriculture is key not only to improving the efficiency of agricultural production and crop yields and quality but also to balancing energy use and preserving a cleaner environment. Biopreparations are environmentally friendly means of restoring the vitality of the soil in which plants can thrive. Biopreparations have an impact on soil health and alter greenhouse gas emissions. The aim of this study was to investigate the effects of different biopreparations on soil porosity, temperature, and CO2 (carbon dioxide) emissions from the soil in northeast Europe (Lithuania) when growing winter wheat and oilseed rape. The experimental studies were carried out over 3 years, and each spring, after the resumption of winter crops, the soil surface was sprayed with biopreparations of different properties or with mixtures of biopreparations under seven scenarios, with one scenario left as a control. Soil porosity, temperature, and CO2 emissions from the soil were measured regularly every month from April to August. The application of the biopreparations showed a cumulative effect on the soil properties. In the third year of the study, the total porosity of the soil was higher in all scenarios compared to the control, ranging between 51 % and 74 %. The aeration porosity of the soil was also higher in all years of the study than in the control, although no significant differences were obtained. The results of the studies on CO2 emissions from the soil showed that, in the first year, the application of the biopreparations increased emissions compared to the control. However, when assessing the cumulative effect of the biopreparations on soil respiration intensity, it was found that, in the third year, most of the biopreparations led to a reduction in CO2 emissions compared to the control. The lowest emissions were achieved with the biopreparations consisting of essential oils of plants, 40 species of various herbs extracts, marine algae extracts, Azospirillum sp., Frateuria aurentia, Bacillus megaterium, mineral oils, Azotobacter vinelandi, humic acid, gibberellic acid, sodium molybdate, Azototbacter chroococcum, Azospirillum brasilense, etc. Evaluating the effectiveness of biopreparations on soil porosity, temperature, and CO2 emissions from the soil, it can be stated that the best effect was achieved in all 3 research years in using biopreparations with Azotobacter chroococcum, Azotospirilum brasilense, various herbs, marine algae extracts, oils of plants, and mineral substances. The multiple-regression model showed that soil temperature has a greater influence on the variation of CO2 emissions than soil aeration porosity.