ENERGY AND ECOLOGICAL ANALYSIS OF THE LIFE CYCLE OF ENERGY USE OF MAIZE CROP RESIDUES

Maize crop residues have significant energy potential in Ukraine. The purpose of this work is to analyze the energy and environmental efficiency of thermal energy production from corn residues, taking into account the sustainability criteria. The task of the work is to quantitatively calculate energy and environmental efficiency indicators and compare them with values that meet the criteria of sustainable development. Using the life cycle assessment methodology, the cases of using bales, pellets and briquettes from plant biomass as fuel in a boiler with a capacity of 500 kW were considered. The calculation of the energy conversion factor and reduction of greenhouse gas emissions has been performed. It is shown that at distances of transportation of finished biofuel not exceeding 150 km, energy indicators (energy yield coefficient, specific cumulative energy demand) are within the recommended values corresponding to sustainable development. The distribution of primary energy consumption of fossil fuels by stages of the life cycle of thermal energy production from maize crop residues is shown. Reductions of greenhouse gas emissions from the introduction of heat production technologies from maize crop residues meet the new requirements of the European Parliament and of the Council Directive on the promotion of the use of energy from renewable sources on the use of renewable energy sources. It is shown that in general the production of pellets and briquettes from corn residues is energetically inexpedient when transporting biomass at a distance that meets the criteria of sustainable development.

Comparison of soil and corn residue cutting performance of different discs used for vertical tillage

High amount of corn (Zea mays L.) residue left in the field interferes with seeding operations, which hinders the viability of conservation agriculture. Vertical tillage is a promising practice in dealing with heavy crop residue, but its effectiveness largely depends on the design and use of tillage machines. In this study, three vertical tillage discs with different shapes, namely notched, plain, and rippled, were tested in a soil bin at two different working depths, shallow (63.5 mm) and deep (127 mm). Corn residues were spread on top of the soil as surface residue. soil cutting forces, soil displacement, and residue mixing with soil, as well as residue cutting were measured. The results showed that the working depth had a stronger effect on the performance of discs as compared to the disc type. No difference in residue cutting was found between the treatments. The deep working depth resulted in 5.1% higher residue mixing, 53.4% greater soil cutting forces, and 34.9% larger soil displacements, as compared to the shallow depth. The rippled disc resulted in the largest soil displacements with the greatest demand in soil cutting forces. Overall, the rippled disc was the most aggressive among the three discs with regard to the performance indicators measured. The results suggested that varying working depth would be an effective approach in changing the soil dynamics and residue cutting performance of the discs for vertical tillage.

MICROBIOLOGICAL PROCESSES OF TRANSFORMATION OF CORN PLANT RESIDUES UNDER INTRODUCTION OF DESTRUCTING MICROORGANISMS IN THE AGROCENOSES

Objective. Investigate the microbiological processes of transformation of plant residues in corn under introduction of microorganisms — producers of cellulase enzyme complexes in the agrocenoses, which play an important role in the biodegradation of fresh organic matter. Methods. Field, microbiological, biochemical, statistical. Results. In the conditions of long-term field experiment on leached chernozem (short-rotation crop rotation: corn for grain – buckwheat – soybean), the microbiological processes at mineralization of 8 t/ha of leaf-stem weight of corn have been investigated. It was found that during the growing season of buckwheat in the soil (the first year after the introduction of corn residues) and soybeans (the second year after the introduction of residues), the number of cellulolytic microorganisms increases. Their number was the highest in buckwheat agrocenoses in the variant using Microbacterium sp. 6633 and amounted to 17.7 million/g of soil, whilst a value in the control variant was 11.3 million/g of soil. The second year after the application of corn residues, the highest rates of the number of these microorganisms were reported in the variant with Bacillus sp. 6605 — 15.6 million/g of soil with control parameters of 11.1 million/g of soil. Under the action of destruction bacteria of organic matter, the enzymatic activity of the soil increased, namely: cellulase, peroxidase and polyphenol oxidase ones. Cellulase activity when using Pseudomonas sp. 6650 and Microbacterium sp. 6633 increased 1.9 times. An increase in the biochemical coefficient of humus accumulation by Muromtsev under the influence of microorganisms introduced into agrocenoses was reported. Conclusion. Under the action of representatives of the genera Bacillus, Microbacterium, Pseudomonas, the processes of mineralization of corn leaf mass in leached chernozem are activated: the number of cellulolytic microorganisms, cellulase, peroxidase and polyphenol oxidase activity increases. Parameters of the biochemical coefficient of accumulation of humus according to Muromtsev indicate an increase in the intensity of decomposition of fresh organic matter under the introduction of plant residues. These microorganisms are promising for the development of a microbial preparation designed to optimize the processes of mineralization-immobilization using crop by-products.

Phyllachora maydis Ascospore Release and Germination from Overwintered Corn Residue

Tar spot of corn, caused by Phyllachora maydis, has been reported in several upper Midwest states in the United States. This has led to expanded efforts to more thoroughly understand the biology of P. maydis and the epidemiology of tar spot. This study determined the potential for P. maydis ascospore release and germination from overwintered P. maydis-infected corn residues from various locations in the upper Midwest. Corn residue samples collected in the spring of 2019 from 12 fields in four states were examined. Ascospore release and germination were observed in all residue samples collected. The mean total number of ascospores released per milliliter of water ranged from 3.6 × 103 to 4.8 × 106 after 4-h incubation and 3.7 × 103 to 4.4 × 106 after 24-h incubation. The mean percent spore germination ranged from 0.7 to 24.1% after 4-h incubation and 2.4 to 24.9% after 24-h incubation. There was a significant inverse relationship between total numbers of ascospores released and the percent germination of the ascospores. Samples from Illinois consistently yielded the greatest total ascospore release but were also consistently among the samples with the lowest percent ascospore germination. Samples from Wisconsin and Indiana were among the lowest for total ascospore numbers but were among the highest for total ascospore germination. These findings provide evidence that P. maydis can overwinter in multiple areas of the upper Midwest. Future research should focus on reducing infested corn residue to reduce initial infection by P. maydis.