Measuring and modelling parameters from hyperspectral sensors for site-specific crop protection

This thesis sought to optimise systems for plant protection in precision agriculture through developing a field method for estimating crop status parameters from hyperspectral sensors, and an empirical model for estimating the required herbicide dose in different parts of the field. The hyperspectral reflectance measurements in the open field took the form of instantaneous spectra recording using an existing method called feature vector based analysis (FVBA), which was applied on disease severity. A new method called iterative normalisation based analysis (INBA) was developed and evaluated on disease severity and plant biomass. The methods revealed two different spectral signatures in both disease severity and plant density data. By concentrating the analysis on a 12% random subset of the hyperspectral field data, the unknown part of the data could be estimated with 94-97% coefficient of determination. The empirical model for site-specific weed control combined a model for weed competition and a dose response model. Comparisons of site-specific and conventional uniform spraying using model simulations showed that site-specific spraying with the uniform recommended dose resulted in 64% herbicide saving. Comparison with a uniform dose with equal weed control effect resulted in 36% herbicide saving. The methods developed in this thesis can be used to improve systems for site-specific plant protection in precision agriculture and to evaluate site-specific plant protection systems in relation to uniform spraying. Overall, this could be beneficial both for farm finances and for the environment

Impact of lowered vehicle weight of electric autonomous tractors in a systems perspective

Modern agriculture rely on heavy machinery that has increased risk of detrimental soil compaction of arable fields. This can lead to negative effects such as reduced yields, reduced field trafficability and increased fuel use. Electric, autonomous tractors makes it possible to replace one heavy machine with several lighter without increased labour costs. In this study, the economic and environmental effects of reduced soil compaction for smaller autonomous tractors were assessed and compared to a scenario with conventional tractors. A discrete event simulation of a Swedish 200 ha grain farm with clay soil was used for the calculations. The electric, autonomous system had lower soil compaction impacts as well as other benefits, and reduced cost in total from 385 to 258 euro ha-1 and the climate impact from 270 to 77 kg CO2eq ha-1 compared to the conventional scenario. Soil compaction constituted 20% of the cost and 26% of the climate impact for the conventional scenario. It was concluded that soil compaction was impactful in machinery studies, especially on heavier soil like clay, and should not be omitted. Soil compaction avoidance alone was not impactful enough to warrant a change to electric, autonomous tractors but it reinforced already existing trends and further improved the cost and environmental benefits

Performance comparison of charging systems for autonomous electric field tractors using dynamic simulation

A model simulating an autonomous battery electric vehicle system for agricultural field use was created, assuming a 200-ha conventional cereal farm in Swedish conditions. The different subsystems were verified against sources in the literature, field experiments and general common practice. The model was used to compare two different charging systems (conductive charging and battery exchange) for battery electric tractors to each other. A comparative simulation was made with conventional diesel systems (fully autonomous or manned for 10 h d(-1)). The simulation results indicated that battery exchange was generally a faster system than conductive charging. The results also showed that both electric systems were able to achieve similar active time during spring field operations as a corresponding system of a simulated manned diesel tractor for battery sizes from 50 kWh and charge powers from 50 kW. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of IAgrE

A Spatially Explicit Decision Support System for Assessment of Tree Stump Harvest Using Biodiversity and Economic Criteria

Stump harvesting is predicted to increase with future increasing demands for renewable energy. This may affect deadwood affiliate biodiversity negatively, given that stumps constitute a large proportion of the coarse deadwood in young managed forests. Spatial decision support for evaluating the integrated effects on biodiversity and production of stump harvesting is needed. We developed a spatially explicit decision support system (called MapStump-DSS), for assessment of tree stump harvesting using biodiversity and economic criteria together with different scenarios for biodiversity conservation and bioenergy market prices. Two novel key aspects of the MAPStump-DSS is that it (1) merges and utilizes georeferenced stump-level data (e.g., tree species and diameter) directly from the harvester with stand data that are increasingly available to forest managers and (2) is flexible toward incorporating both quantitative and qualitative criteria based on emerging knowledge (here biodiversity criteria) or underlying societal drivers and end-user preferences. We tested the MAPStump-DSS on a 45 ha study forest, utilizing harvester data on characteristics and geographical positions for >26,000 stumps. The MAPStump-DSS produced relevant spatially explicit information on the biodiversity and economic values of individual stumps, where amounts of "conflict stumps" (with both high biodiversity and economical value) increased with bioenergy price levels and strengthened biodiversity conservation measures. The MAPStump-DSS can be applied in practice for any forest site, allowing the user to examine the spatial distribution of stumps and to obtain summaries for whole forest stands. Information depicted by the MAPStump-DSS includes amounts, characteristics, biodiversity values and costs of stumps in relation to different scenarios, which also allow the user to explore and optimize biodiversity and economy trade-offs prior to stump harvest

A comparison of biological effect and spray liquid distribution and deposition for different spray application techniques in different crops

The objective of this study was to compare a selection of spray application techniques with different application volumes, with respect to the spray liquid distribution on flat surfaces, the deposition in fully developed crops and the biological effect. The spray application techniques in this study were conventional spray technique with three different nozzles: Teelet XR, Lechler ID and Lurmark DriftBeta, and also AirTec, Danfoil, Hardi Twin, Kyndestoit and Släpduk. The dynamic spray liquid distribution was measured on a flat surface, spraying a water and black dye solution on pre-glued wallpaper lengths. Spraying the same dye-water solution in established crops, the spray deposition on plant and on the ground was studied by measuring the absorbance of sampled leafs' and collectors' rinsing water. Spray deposition studies were made in winter wheat and potato. The biological effect was studied in field experiments with plots with linearly increased dose. The field trials in this study were weed control in spring barley, fungi control in winter wheat and potato late blight control. The weed weight was sampled and visual assessments were made of the infection of fungi. Grain yield and 1000-kernel-weight were sampled in the wheat trial. The dynamic spray liquid distribution resulted in coefficients of variation, for all spray techniques, between 5% and 16%, which were considered to be at acceptable levels. Relatively large significant differences were found in the spray deposition measurements in potato canopies. For conventional spray technique, 90% spray deposition was recovered in the top of the canopy. Higher deposition was recovered in the lower part of the canopy and on the ground for Danfoil, Hardi Twin and Släpduk than the other techniques. In the wheat crop, the differences in spray deposition between spray techniques were smaller. Släpduk had the greatest increase in liquid deposition on the head and the flag leaf. The techniques with external air assistance, Hardi Twin and Kyndestoft, had the lowest deposition on the ground. Analysing the effect of weed control in spring barley, fungi control in wheat and potato late blight control, no significant differences were found. This might be seemed remarkable when large differences in spray liquid deposition were found in the potato canopy. One conclusion could be that the penetration ability in dense potato canopies is not of equal importance as to protect the upper parts of the canopy. It is indicated that it could be important to consider other factors, not included in this study, such as the ability to reduce drift and increase capacity, when selecting spray application techniqu

Life Cycle Assessment of Autonomous Electric Field Tractors in Swedish Agriculture

There is an increased interest for battery electric vehicles in multiple sectors, including agriculture. The potential for lowered environmental impact is one of the key factors, but there exists a knowledge gap between the environmental impact of on-road vehicles and agricultural work machinery. In this study, a life cycle assessment was performed on two smaller, self-driving battery electric tractors, and the results were compared to those of a conventional tractor for eleven midpoint characterisation factors, three damage categories and one weighted single score. The results showed that compared to the conventional tractor, the battery electric tractor had a higher impact in all categories during the production phase, with battery production being a majority contributor. However, over the entire life cycle, it had a lower impact in the weighted single score (-72%) and all three damage categories; human health (-74%), ecosystem impact (-47%) and resource scarcity (-67%). The global warming potential over the life cycle of the battery electric tractor was 102 kg CO(2)eq.ha(-1) y(-1) compared to 293 kg CO(2)eq.ha(-1) y(-1) for the conventional system. For the global warming potential category, the use phase was the most influential and the fuel used was the single most important factor

Graderingsmetodik i ogräsförsök

Många länder har övergått till okulär ogräsgradering istället för att dokumentera effekterna av kemiska ogräsbekämpningsmedel genom räkning och vägning av ogräs, normalt fyra veckor efter sista bekämpningen, vilket är det normala tillvägagångssättet i svenska försök. Syftet med detta projekt var därför att studera möjligheterna att övergå till okulär bedömning i svenska försök, att utbilda försökspersonal i graderingsmetodik, samt att studera möjligheterna att införa bildanalys för bedömning av ogräsmängd och ogräseffekt

Cost analysis of autonomous battery electric field tractors in agriculture

Interest in the electrification of agricultural vehicles is increasing along with growing interest in autonomous vehicles. Individual technologies have been well-explored, but not their combined use and the effects on agricultural fieldwork. In this study, cost analysis was conducted based on a simulated vehicle system with 50 kW self-driving battery electric drive (BED) tractors. The analysis included battery degradation due to cycling and the cost of inadequate machine capacity, as these factors are suspected to be problems for electric tractors. A dynamic discrete-event vehicle system model, a linear timeliness model and a one-dimensional battery cell ageing model were assumed. Costs obtained were compared with those of contemporary manned diesel-based systems. BED systems had equal or lower annual costs compared to conventional manned diesel-based systems; this was due to lower costs for fuel and maintenance, while providing adequate capacity and lower energy usage. Sensitivity analysis showed that operating costs were of greater significance than investment costs. The generally more expensive investment costs of BED systems were outweighed by the reduced operating costs for several different BED system systems. Battery degradation costs and timeliness were influential, but not sufficient to make the system uncompetitive. The synergistic effect of vehicular autonomy and BED outweighed several of the drawbacks of BED systems, such as frequent recharging, increased transport and reduced consecutive work time. ? 2021 The Authors. Published by Elsevier Ltd on behalf of IAgrE. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0