Influence of stubble biodestructor on soil microbiological activity and grain yield of winter wheat (Triticum aestivum L.)

The aim of the work was to improve soil fertility and increase the yield of winter wheat using the stubble biodestructor by activating the microbiological activity of the soil. The experimental studies were on the research field of Mykolayiv National Agrarian University (Ukraine). After harvesting the precursor cultures of spring barley and peas the post-harvest residues of these crops were treated with a stubble biodestructor. After treatment of crop residues of spring barley and pea by the stubble biodestructor in the soil layer of 0 up to 20 cm the quantity of cellulose-destructive microorganisms increased by 27.9·105 up to 36.0·105 cfu/g of soil depending on the predecessor culture and the degree of degradation of these residues increased by 31.4 up to 45.1%. The number of nitrogen fixators in the 0-10 cm soil layer grew under the action of treatment of crop residues of spring barley and peas by stubble biodestructor on 13.4 up to 14.1 ·106 cfu/g of soilor 30.3 up to 35.0%. At the same time, a somewhat large number of bacteria in the soil was determined by the processing of post-harvest residues of peas, which was due to the biological characteristics of this legume culture. The average for years of researches at cultivating of winter wheat after spring barley using the stubble biodestructor the grain yield increased by 0.45 t ha–1, or 20.9%, and after pea it increased by 0.67 t ha–1 or 18.8% compared to the treatment variant of stubble just with water.

Greenhouse Gas Emission Offsets of Forest Residues for Bioenergy in Queensland, Australia

Harnessing sustainably sourced forest biomass for renewable energy is well-established in some parts of the developed world. Forest-based bioenergy has the potential to offset carbon dioxide emissions from fossil fuels, thereby playing a role in climate change mitigation. Despite having an established commercial forestry industry, with large quantities of residue generated each year, there is limited use for forest biomass for renewable energy in Queensland, and Australia more broadly. The objective of this study was to identify the carbon dioxide mitigation potential of replacing fossil fuels with bioenergy generated from forest harvest residues harnessed from commercial plantations of Pinus species in southeast Queensland. An empirical-based full carbon accounting model (FullCAM) was used to simulate the accumulation of carbon in harvest residues. The results from the FullCAM modelling were further analysed to identify the energy substitution and greenhouse gas (GHG) emissions offsets of three bioenergy scenarios. The results of the analysis suggest that the greatest opportunity to avoid or offset emissions is achieved when combined heat and power using residue feedstocks replaces coal-fired electricity. The results of this study suggest that forest residue bioenergy is a viable alternative to traditional energy sources, offering substantive emission reductions, with the potential to contribute towards renewable energy and emission reduction targets in Queensland. The approach used in this case study will be valuable to other regions exploring bioenergy generation from forest or other biomass residues.

Degradation of hop latent viroid during anaerobic digestion of infected hop harvest residues

The citrus bark cracking viroid (CBCVd) was identified as causal agent for a severe stunting disease in hops. Viroids are highly stable parasitic RNAs, which can be easily transmitted by agricultural practices. Since CBCVd has recently been detected in two European countries a growing concern is that this pathogen will further spread and thereby threaten the European hop production. Biogas fermentation is used to sanitize hop harvest residues infected with pathogenic fungi. Consequently, the aim of this study was to test if biogas fermentation can contribute to viroid degradation at mesophilic (40 °C) and thermophilic (50 °C) conditions. Therefore, a duplex reverse transcription real-time PCR analysis was developed for CBCVd and HLVd detection in biogas fermentation residues. The non-pathogenic hop latent viroid (HLVd) was used as viroid model for the pathogenic CBCVd. The fermentation trials showed that HLVd was significantly degraded after 30 days at mesophilic or after 5 days at thermophilic conditions, respectively. However, sequencing revealed that HLVd was not fully degraded even after 90 days. The incubation of hop harvest residues at different temperatures between 20 and 70 °C showed that 70 °C led to a significant HLVd degradation after 1 day. In conclusion, we suggest combining 70 °C pretreatment and thermophilic fermentation for efficient viroid decontamination.

Removing Harvest Residues from Hardwood Stands Affects Tree Growth, Wood Density and Stem Wood Nutrient Concentration in European Beech (Fagus Sylvatica) and Oak (Quercus spp.)

Background: Increased exportation of harvest residues from forests, to mitigate excessive demand for woody biomass, have reportedly diminished soil mineral resources and may lead to degraded tree nutrition and tree growth. However, as nutrients become less available in the soil, the remobilization of nutrients in biomass tissues (plant internal cycling) helps sustain tree nutrition. Our study aims to quantify the impact of Removing Harvest Residues and Litter (RHRL) during five years on tree growth, wood density and stem wood nutrient concentrations in young beech and oak forest stands.Result: Our study found that, RHRL significantly decreased the tree growth ring width, by 14%, and wood density, by 3%, in beech trees, in the near bark rings. RHRL also significantly reduced the nutrient concentration in the near bark and near pith area of both species. Mg, Na and S were found lower by 44%, 76% and 56%, respectively, in the near bark area of beech trees, and K, Ca, Mg, Na, S and Fe were lower by 20%, 25%, 41%, 48%, 41% and 16%, respectively, in the near bark area of oak trees. K and Mg concentrations decreased more strongly in the near pith area compared to the near bark area suggesting internal translocation of these two elements. Conclusion: In beech trees, wood density proved to be an important factor while quantifying the effect of removing harvest residuals on the tree growth and biomass. Soil nutrient loss intensified the remobilization of nutrients contained in older tree rings (close to the pith) towards newly formed rings (close to bark). In our study, in beech trees, K was found to be the most recycled major nutrient. These results demonstrate the potential of such analysis for providing valuable insight into the effect of RHRL in premature stands on the physiological adaptive strategies of trees and an indication of soil fertility and acidity status.

Catch Crops: A Nutrient Reservoir in Post-Harvest Residues under Water Deficit

Undersowing catch crops (CCs) in cereals provides many environmental benefits and potentially contributes to building agricultural resilience to climate change. The increasing soil water deficit due to global warming is becoming a challenge for the sustainability of Central European agriculture. Some of the multiple functions of CCs may be altered under water shortage. Two pot experiments were conducted in Poland to assess the effect of water deficit on N, P, K, and Mg accumulated in post-harvest residues left by spring barley undersown with Italian ryegrass or red clover, and in the soil under these crops. In both experiments, barley grown alone provided a reference, and two levels of water supply were adopted: higher (sufficient for barley) and lower (reduced by 50%). Under water deficit, CCs undersown in spring barley maintained their function of capturing and storing nutrients. Post-harvest residues of barley undersown with CC and stressed with water shortage accumulated the same or higher amounts of N, P, K, and Mg than residues of barley grown alone under sufficient water supply. Soil nutrient contents were negatively correlated with crop biomass. Further research with other CC species and studies based on field experiments under rainout shelters are recommended.

Retention of eucalyptus harvest residues reduces soil compaction caused by deep subsoiling

Eucalyptus harvesting, forwarding and soil tillage operations are among the main causes for compaction of forest soils, with potential impacts on productivity. This concern is especially important in areas with soils that are naturally compacted (fragipans and duripans). In these soils, tillage operations include the use of subsoilers that can reach depths of more than one meter and require heavy tractors that exert high pressure on the soil. One of the ways to try to minimize the effect of this compaction is by retaining harvest residues. The objective of this study was to evaluate the impacts of eucalyptus harvesting on soil physical attributes, as well as to determine the potential of different types of residue management to reduce compaction from the soil tillage operation. Two experiments were conducted in the same area with a Yellow Argisol. In the first experiment, compaction caused by mechanized harvesting with harvester + forwarder was evaluated. In the second experiment, different managements of harvest residues were examined as potential modifiers of soil compaction during tillage for new plantings. For this, three managements systems were tested: (1) retention of all harvest residues and litter from the previous rotation (HR + L), (2) retention of litter from the previous rotation (L), and (3) removal of harvest residues and litter from the previous rotation (WR). Before and after harvest, sampling was carried out in the planting rows and inter-rows, and after tillage, samples were collected in the traffic line of the subsoiler-tractor set. In both experiments, undisturbed soil samples were collected from the center of the 0–10, 10–20, 20–40, 40–60, and 60–100 cm layers to determine soil density and total porosity. In each period and site of evaluation, mechanical resistance to penetration up to the 60-cm depth was also determined. The harvesting operation increased soil density at 0–10 and 60–100 cm depths only in the inter-rows. Retention of harvest residues and litter (HR + L) after harvesting avoided increases in soil density and penetration resistance caused by machine traffic during tillage. The results indicate the importance of retaining harvest residues on forest soils for achieving sustainable utilization and for conserving soil quality.

Energy efficiency of technology of cultivation of agricultural crops on the irrigated lands of the South of Ukraine

The article reflects the results of research on the study of crop rotation productivity and energy efficiency components of crop rotation technology in terms of depending on different methods and depth of basic tillage. The purpose of the research was to determine the impact of basic tillage and fertilization on crop rotation productivity indicators and indicators of economic efficiency of crop rotation technology in irrigated conditions in the south of Ukraine. Methods: the field, in-gravimetric, visual, laboratory, calculation-comparative, mathematically-statistical and confessedly in Ukraine methods and methodical recommendations. The research was conducted during 2016-2019 in the research fields of the Askanian SARS IIA NAAS of Ukraine. Results. The use of differentiated and shallow single-depth system of basic tillage to the same productivity indicators at the level of 8.21 and 8.22 t.o.o./ha of products. However, the use of shallow tillage with different depths increased the productivity to 8.49 tons of water/ha, or 3.3%, and with no-till the lowest productivity was obtained 7.15 tons of water/ha. At the same time, the organo-mineral system of fertilizer N90P40 + green manure + crop residues yielded at the level of 7.61 tons per hectare. The improvement of nitrogen nutrition of crop rotations to N105P40 + green manure to get her with the earning of crop residues increased this figure to 8.06 ton so.o./ha, or 5.9% more than the control. At the same time, the maximum productivity indicators of 8.52 tons per hectare were obtained for the N120P40 system + green manure + post-harvest residues, which is actually 12% more than in the control. The reduction of total energy consumption was obtained with a shallow single-depth system of main cultivation of 26.45 GJ/ha, and the lowest values of 25.27 GJ/ha were obtained with no-till, which is 6.8% less than in the control. Application of organo-mineral fertilizer system N90P40 + green manure + post harvest residues formed costs at the level of 24.94 GJ/ha, increase of nitrogen nutrition of crop rotations to N105P40 + green manure with post harvest residues increased costs to 26.35 GJ/ha, and the highest costs 26.37 GJ/ha was obtained in the variant N120P40 + green manure, where the figures were higher by 11.5% compared to the control. Almost the same energy yield was obtained for differentiated and single-depth shallow tillage systems 127.33 and 127.64 GJha, respectively. The application of the system of multi-depth tillage increased the yield to 133.24 GJ/ha. Conclusion. The calculation of energy efficiency testifies that growing of agricultural cultures at bringing of N120Р40 + green manure + post-harvest residues in the system of the plowless on different depth is most expedient and justified from the power point of view. Technology of growing, which is based on these agrotechnology measures provides the receipt of maximal energy coefficient at the level of 4,96