Traditionally, tractors have been built either for tracks or wheels, with tracks mainly on heavy tractors with high power. Today, it is possible to retrofit four separate track units on a conventional agricultural tractor, creating interesting possibilities for agriculture. The objective of the present study was to compare soil compaction and traction for tracks, single and dual wheels mounted on the same tractor type. Measurements were made on two clay soils (Eutric Cambisols) in Sweden in 2009, using an 85kW tractor with a total weight of 7700kg. The rubber track system consisted of four tracks mounted on the conventional wheel axles of the tractor. The measured stresses were similar for the tracks and dual wheels at all depths studied (15, 30 and 50cm), but were considerably higher for the single wheels at all depths. Simulations of soil stresses correlated closely to measured values for the tracks and the dual wheels, but underestimated soil stresses in the topsoil compared to measured values for the single wheel. Bulk density and penetration resistance were consistently highest and saturated hydraulic conductivity lowest after wheeling with single wheels, while there were no statistically significant differences between tracks and dual wheels. With single wheels and the tractor loaded, saturated hydraulic conductivity decreased to 0.01mh-1 from 0.13mh-1 in the control, while bulk density increased from 1.24 to 1.36Mgm-3. The stress distribution in the driving direction was relatively even along the front and rear tracks, which is an advantage compared with a long single track, which often has an uneven longitudinal stress distribution. Slip was significantly higher for the dual and single wheels compared with tracks. To utilise the large contact area of the tracks, the tractor should have a low weight in relation to the engine power. © 2011 Elsevier B.V.

The agricultural industry plays a crucial role in transitioning towards a sustainable and fossil-free future. This article explores the potential of biorefineries using biomass from agriculture to reduce emissions and promote self sufficiency. Regarding a concept that integrated anaerobic digestion, grass and legume protein production, and hydrothermal liquefaction. A case study was conducted in the southwestern part of Sweden, involving interviews with a biogas plant and local farmers. The study analyzed the utilization of input goods in agriculture and evaluated the potential of biomass in the area. To assess the potential for farms to become self-sufficient in fuel, protein feed, and plant nutrients. The results show an overall positive outlook of the biorefinery concept. By utilizing 20% of the available biomass in the area can the biorefinery concept annually produce 100 GWh of biogas, 3800 tonnes of grass and legume protein concentrate and 1200 GWh bio-oil. This could theoretically cover 100 % of the need of soy meal, 44% for nitrogen, 50% for phosphorus and 100% for potassium.

Agricultural Biorefinery - combining local and regional scale In order to achieve Sweden's sustainability goals and an increased degree of self-sufficiency, our resources need to be used in an innovative way. Resources that today are classified as residual streams can be used in a smarter way to produce the future's food, feed, fuel and energy. There is a great potential in utilizing agricultural biomasses. In the project, the potential of agriculture to supply ILUC-free feedstock to a local and regional biorefinery concept was calculated and the system was evaluated through mass and energy flow calculations, cost calculations and case descriptions on Vårgårda Herrljunga Biogas Plant (VH Biogas). In addition, practical tests were carried out on bio-oil production from dewatered digestate from participating biogas plants. Quantifications were also carried out of how the concept contributes to more resource-efficient crop cultivation with maintained humus content in soil despite increased removal of biomass from the farm. ...

The aim of this project was to take a closer look at problems connected to combustion of energy grain in a systematic way. The work was restricted to appliances of 100 - 400 kW. Eight users of energy grain were interviewed about there experiences. The majority had smaller problems, besides from relatively many running-in problems, presumably because the instructions for installation and operation were insufficient. Shutdowns were rare and caused by sintering. Burning other cereals than oat often led to sintering. Corrosion is avoided by keeping the flue gas temperature high. Measurements were performed on three boilers for energy grain. Measured carbon monoxide was 70 - 900 mg/Nm3, OGC 0 - 28 mg/Nm3, nitrogen oxides 490 - 945 mg/Nm3 and dust 160 - 440 mg/Nm3. All emissions were higher compared to pellets. Sulphur dioxide and hydrochloric acid were estimated from fuel analysis, and were higher than from combustion of wood. Energy grain does not contribute to global warming and have good properties in the form of high heating value, relatively high density and the grain has a size and form easy to combust. The Swedish Board of Housing, Building and Planning prescribes maximum allowed levels of OGC. The boilers studied in this project had emission well below these limits. For boilers < 500 kW, there are no legislations or recommendation that restrict emissions of dust, nitrogen oxides, sulphur dioxides or hydrochloric acid. The lack of legislation/recommendations makes it difficult to judge whether the emissions are acceptable or not. Today, boilers for energy grain are designed to give low emissions of unburned components and not optimised for low emissions of nitrogen oxides. By changing the design of the burner (it was equipped with three steps with air holes) the emissions were reduced by 27 % without an increase of unburned components. The objective with the steps was to divide the combustion into two zones: one with deficit of oxygen and one rich with oxygen. It is probable possible to reduce the emission even more by dividing the combustion in an even more sophisticated way. Measurements in three different boilers showed that dust emission from one of the boilers that used modulating power regulation was substantially lower than from the other two that were controlled by an on-off thermostat. This may be explained by higher degree of ash pulled by the gas flow at high power, or by lower temperature in the glow bed at low power. However, more data is required to draw general conclusions. Emissions of dust, nitrogen oxides, sulphur dioxide or hydrochloric acid constitute an obstacle for a considerable expansion of energy grain and similar fuels; because the emission will be paid attention to if they increase, especially if they increase in connection to densely populated areas. Therefore, a continuous increase of combustion of energy crops should be accompanied by continuous improvements of combustion technique to reduce the emissions.

The interest for growing grass seed is increasing in Sweden, and there is a potential from several foreign seed companies that would like to establish contacts with growers. Thus, the Swedish growth of grass seed is small compared to other countries in Europe. Growing grass seed is an economical unsure crop, the yield is much controlled by pollination and weather during harvest, as well as access to technical equipment during harvest, drying and storage. One important thing to a successful growth is to reduce losses during harvest. White clover grows low (only 10-15 cm high) and is therefore hard to put up on the header without losses. According to studies as much as 30% of the biological yield can be lost thru wrong settings of combine during harvest. Also, the germination of the seed can be lost due to hard treatment in the combine. Special equipment for grass seed growth is often expensive and is not always a profitable affair for the farmer. Here there are opportunities for improvements of existing techniques. This study aimed to raise profitability for the growth of white clover (Trifolium repens), primary by reducing losses during harvest. The goal was to develop performance enhancing solutions for a traditional combine reel, while at the same time facilitating the driver´s work to create even input in the combine. 4 different alternatives were tested during field trial in the summer of 2020. The results show that a specially designed pickup header gave the lowest losses during racking up white clover. Thus, it had the highest contents of soil minerals in tested seeds. The tested modifications of a traditional reel, reducing rod distance to 6 cm and to replace the rods with a brush, unfortunately did not had the desired effects. For both these alternatives the losses from the header and the losses behind the combine were higher than for a traditional header with rod spacing 12 cm. The brush mounted, with the aim to softly rake the crop up on the header where to soft and were bended, and the desired effect were not achieved.