Efficiency of Combed Straw Harvesting Technology Involving Straw Decomposition in the Soil

This article deals with the problem of harvesting combed straw by mixing it with the soil and the process of combed straw decomposition in particular. The idea and purpose of the research are also analysed in terms of circular economy, which represents a closed cycle. Combed straw is seen as a by-product which is reused as fertilizer to increase soil fertility, thus reducing the negative impact on the environment and increasing the efficiency of organic matter use. To analyse the qualitative aspect of the process, the introduction of an indicator is proposed—the straw decomposition coefficient. Experimental studies of straw decomposition in the soil were carried out using the mathematical theory of experimental design, where the response function is represented by the functional dependence of the straw decomposition coefficient on the length of its cutting and nitrogen and phosphorus application doses. For experimental studies, Box–Behnken design was used, which made it possible to calculate the regression coefficients by known formulas. Verification of the obtained coefficients according to Student’s t -test showed that all of them were significant. According to Fisher’s test, it was established that the model is adequate and can be used for further research. As determined by the experimental study, shredded straw incorporation improves soil properties and increases its biological activity. Ultimately, this improves plant nutrition and increases crop yields. The experiment results showed that reduced amounts of nitrogen and phosphorus fertilizers can be applied, thus leading to a reduction in the direct production costs of growing cereals in the following year. The integration of several technological processes, such as straw cutting, shredding, and incorporating it into the soil with simultaneous application of nitrogen and phosphorus fertilizers, increases the economic efficiency of grain production and a shortens the payback period for investment.