Investigations about the impact of the sowing time and rate of the biomass yield and quality of industrial hemp

ArticleThe aim of this study was to find the optimum sowing rate of industrial hemp (Cannabis sativa L.) and to clarify the impact of the sowing rate on the production of biofuel from hemp biomass in Latvia. Field trials were carried out at the Research and Study Farm ‘Pēterlauki’ of the Latvia University of Agriculture in 2012–2014. The industrial hemp (Cannabis sativa L.) ‘Futura 75’ was sown in a Luvic Endogleyic Stagnosol soil: pHKCl 6.7; P – 52 mg kg-1 ; K – 128 mg kg-1 ; the organic matter content – 21–25 g kg-1 . Hemp was sown in 10-m2 plots, triplicate, on May 8 and 17. The total sowing rate was 20 (100), 30 (150), 40 (200), 50 (250), 60 (300), 70 (350), 80 (400), 90 (450), and 100 (500) kg ha-1 (germinating seeds per 1 m2 ). The plots were fertilised as follows: N – 120 kg ha-1 ; P2O5 – 80 kg ha-1 ; and K2O – 112 kg ha-1 . Hemp was harvested when the first matured seeds appeared. The biometrical indices (height and stem diameter), harvesting time, the amount of fresh and dry biomass, and the fibre content were evaluated. Depending on the sowing rate, the yield of dry matter was on average 9.2–12.1 t ha-1 when hemp was sown at the beginning of May, and 7.9–10.0 t ha-1 when hemp was sown in the middle of May

A mathematical model of the plane-parallel movement of an asymmetric machine-and-tractor aggregate

Technological peculiarities of cultivation and harvesting of some agricultural crops make it necessary to use asymmetric machine-and-tractor aggregates. However, for the time being there is no sufficiently complete, analytical study of the steady movement of such machine-and-tractor aggregates. This necessitates the development of a theory of stable movement of the aggregates which would allow choosing their optimal kinematic and design parameters. On the basis of the results of mathematical simulation, a system of linear differential equations of the second order is obtained describing transverse displacement of the center of masses of the aggregating wheeled tractor and turning of its longitudinal axis of symmetry by some angle around the indicated center of mass, as well as the deviation angle of the rear-trailed harvester from the longitudinal axis of the tractor at any arbitrary moment of time. This system of differential equations can be applied for numerical calculations on the PC, which will make it possible to evaluate the stability of the movement of the asymmetric machine-and-tractor aggregate when it performs the technological process

Assessment of the greenhouse gas emissions and energy inputs applying different weed control methods for wheat growing

Received: January 25th, 2023 ; Accepted: May 21st, 2023 ; Published: June 17th, 2023 ; Correspondence: [email protected] indicators are often used to evaluate and select technologies, determining the production costs of the product. However, according to the EU's green course, the ecological assessment of technologies is increasingly important. The purpose of the article is to comparatively evaluate two winter wheat weed control methods, which are widely used in Latvia, according to two ecological indicators - the amount of the GHG emissions and the energy consumption, to find out whether these indicators can serve as a criterion for the selection of technologies. These two methods are HA (harrowing), in which weeds are controlled by harrowing and herbicides, HE (herbicides), in which weeds are controlled only by herbicides. The methodology for calculating the mentioned indicators was developed by analyzing several studies by other authors. The total GHG emissions generated are calculated as the sum of five components: emissions, generated for the manufacture and delivery of the machinery used; emissions, generated by the fuel, consumed for implementation of the technology; emissions, generated for the production, delivery and installation of fertilizers; emissions, generated for the production, delivery and installation of pesticides, seed production, delivery and installation emissions. Analogously, the total energy consumption is calculated by summing the components The technologies were implemented on a specific farm, with the machinery of this farm, labor, fertilizers and the plant protection products. It has been established that the technologies differ by the calculated ecological indicators within the range of 1.2–2.6%; moreover, these indicators are lower for the technology with the herbicide spraying, and the technology is simpler to implement. Therefore, it is also more widely used. Since the coefficients for the calculation of the ecological indicators can be applied by the methodology of this article, the characteristics of the technique and the doses of fertilizers and the plant protection agents, used on the farms, are known, the ecological indicators can be used as an additional criterion for the selection of technologies on the farms. The ratio of the energy value and energy consumption of the produced product (the output and the input ratio) was also determined, this indicator for technologies HA and HE being, respectively, 8.30 and 8.41. In comparison with the research by the authors in other countries, from the point of view of the amount of the generated CO2-eq emissions and rational consumption of energy, the analysed winter wheat production technologies are evaluated as moderately efficient, but from the point of view of the energy value of the product produced and the ratio of the energy consumption (the output and the input ratio) - as efficient

The efficiency of nitrogen fertilizer on the dry matter yield of tall fescue and festulolium grown as feedstock for combustion

ArticleGrass biomass grows during one vegetation season and can be cultivated and consumed at the place of breeding. Grass biomass can be used not only in traditional feed, but, recently, also for energy production (biogas, solid fuels). The most important economic indicator for any crop is its productivity. The study found that it is important to use nitrogen fertilizer to increase the productivity of tall fescue and festulolium. A significant increase (p < 0.05) in the yield of tall fescue was observed starting from the nitrogen norm of 60 kg ha-1 N. Further increase in nitrogen fertilizer norm provides a significant increase in dry mater yield of tall fescue (reaching 8.64 t ha-1 ) and festulolium (reaching 8.11 t ha-1 ) at 180 kg ha-1 N. The analysis of linear regression coefficients of polynomials showed that the highest nitrogen efficiency in the first year of the use of tall fescue was achieved at the norm of 180 kg ha-1 N, but for festulolium – at the norm of 120 kg ha-1 N. In the following years of tall fescue use, the highest efficiency of nitrogen norms differed: in the 2nd and 4th year of use – at 60 kg ha-1 N, in the 3rd year of use – at 30 kg ha-1 N, and in the 5th year of use – at 120 kg ha-1 N. In contrast, for festulolium, in the 2nd year of use, the highest nitrogen efficiency was reached at the norm of 30 kg ha-1 N, and in the 3rd–5th year of use – at the norm of 60 kg ha-1 N

Results of experimental investigations of a flexible active harrow with loosening teeth

ArticleSoil tillage processes significantly affect the growth of cultivated plants; therefore, improvement of various designs and combinations of ploughs is still an actual practical and scientific task. This paper presents investigations of the design of a soil tillage machine consisting of three plough bodies equipped from the lateral side with a module with a flexible active harrow driven by a support wheel. The technological process of tillage by this machine is carried out in such a way that the module of the flexible active harrow is installed at a certain depth of soil tillage. The purpose of this work is an experimental comparative investigation of the quality indicators of the work of a design of the soil tillage working body with a flexible active harrow having loosening teeth. In the process of comparative experimental investigations of the operation of ploughs with a standard flexible harrow and an experimental active harrow having loosening teeth, the soil lumpiness (characterising the quality of crumbling) and water permeability of the obtained soil structure were estimated. An experimental model of this working tool was tested under the production conditions, and it showed advantages of loosening and crumpling the soil compared to the conventional harrows. This can be explained by the fact that the harrow tines, freely mounted on the axes of its links, ensure their oscillatory movements when moving in two different planes, thereby creating conditions for more intense soil disintegration

Operational and technological properties of ploughing block-modular machine-and-tractor aggregate

One of the topical directions in the development of agricultural tractor construction can be the formation of machine-and-tractor units according to a modular principle, using technological modules with the driving wheels. The aim of this work is to study the possibilities how to increase the operational and technological indicators of the operation of an agricultural aggregate in a modular aggregation system due to the selection of rational parameters of an elastic-dissipative connection of the energy and the technological modules. The obtained data were processed by statistical methods on a PC, using correlation and dispersion analyses. It has been established by experimental investigation that the operation of a ploughing block-modular aggregate, while ensuring rational rigidity of the connection of its energy and technological modules, is achieved by throttling the hydraulic system of its rear suspension at the level of 75%, characterised by an increase in its performance by 6% and a decrease in the specific fuel consumption by 12.4%. In addition, the level of vertical vibration load of the operator corresponds to the allowed fatigue rate for 8 h of work

Theory of grain mixture particle motion during aspiration separation

The practice of separating grain mixtures with the use of the difference in the aerodynamic properties of their components has proved that the process of separating mixtures in the aspiration separator is the most promising one with regard to the improvement of quality and intensification of production. The authors have developed a new improved design of aspiration seed separators, in which the work process of separating seed material is performed with the use of vibration processes. In this seed material separator, the constant force air flow that acts on the sail members on the central pipe of the separator, when seeds are fed for processing, generates self-excited oscillations in the pipe, which produces centrifugal forces of inertia in the seed feeding system. As a result of the mentioned effect, the propelling force in the process under study substantially increases, accelerating the seeds of different fractions, which differ in their masses, to different velocities. The motion paths of the seed particles change accordingly, heavier particles moving closer to the vertical axis of the aspiration channel, which provides for increasing the efficiency of separation of the seeds of different fractions from each other. In this paper, a new mathematical model is developed for the motion of a seed mixture material particle in the operating space of the separator’s aspiration channel. The mathematical modelling of the process of vibration and aspiration separation has indicated that the separation of the motion paths of the medium and heavy fractions takes place within the range of 20–40 mm; the flying speed of the particles is equal to 3.2–8.0 m s–1, respectively; and their acceleration is equal to 1.8– 3.3 m s–2, which provides the necessary conditions for the accurate and high quality separation into the required fractions. In view of the found differences between the kinematic characteristics of the separated fractions of the grain mixture, the diameter of the pipeline for the medium fraction is to be within the range of 90–100 mm, for the heavy fraction – 50–70 mm

A Novel Approach for Transmission of 56 Gbit/s NRZ Signal in Access Network Using Spectrum Slicing Technique

We present the spectrum slicing and stitching concept for high-capacity low optics complexity optical access networks. Spectrum slicing and stitching of a 56 Gbit/s NRZ electrical signal is experimentally demonstrated for the first time. We present the spectrum slicing and stitching concept for high-capacity low optics complexity optical access networks. Spectrum slicing and stitching of a 56 Gbit/s NRZ electrical signal is experimentally demonstrated for the first time