Prospects and limitations for agricultural engineering in the development of sustainable weed control methods – examples from European research

This paper gives a brief review of the major achievements in European research on physical weed control methods for agricultural and horticultural crops. Most of the work has emerged from an increasing awareness and concern about pesticide consumption in many Western European countries. Also an increasing interest in organic farming has further pushed the development of more sustainable weed control methods. Generally, the research has been joint projects between engineers and agronomists and the results have so far revealed some prospects as well as limitations for non-chemical methods to become useful solutions, not only for the organic growers but also for the conventional ones. A number of investigations have focussed on rather simple low-tech mechanical weeding principles, such as harrowing, brush weeding, hoeing, torsion weeding, and finger weeding, aiming at describing the weeding mechanisms for a better optimisation of the usage. In some crops, such as transplanted vegetables, potatoes, maize, winter oil seed rape, and partly small grain cereals, mechanical weed control has been quite effective and may become a relevant alternative to chemical weed control. However, current mechanical methods generally work with low selectivity, as they do not distinguish between weed and crop plants when applied into the crop row. Attempts to change the constructions and materials of the weeding tools have not decisively improved the selectivity and more intelligent methods capable of controlling only the weeds are therefore needed. The first step in that direction was the introduction of electronic steering systems for automatic guidance of inter-row hoes. They are based on image analysis of the crop row, and the technology is considered to be a kind of platform for the development of more advanced systems for robotic weeding in the rows of row crops, such as sugar beets, maize, and most vegetables. However, recent studies have shown that such an ambition may be difficult to fulfil because weed plants growing right beside the crop plants are the most harmful ones in terms of suppressing the crop plants. Whether any computer-based system would be able to guide a cutting device with sufficient accuracy and speed to remove those weeds in a practical situation in row crops seems questionable. Hence, other projects have been started with a view to avoid this challenge, trying to look for less complicated methods with more short-termed prospects of being applicable in practice. Steaming the soil prior to crop establishment and in bands corresponding to crop rows appears to have some potential in that context since an almost complete intra-row weed control can be achieved without affecting the crop. However, as with most other thermal methods, high energy consumption is a key-issue that needs to be solved

Organic Farming Scenarios: Operational Analysis and Costs of implementing Innovative Technologies

The objective of this study has been to design a number of farm scenarios representing future plausible and internally consistent organic farming enterprises based on milk, pig, and plant production and use these farm scenarios as the basis for the generation of generalised knowledge on labour and machinery input and costs. Also, an impact analysis and feasibility study of introducing innovative technologies into the organic production system has been invoked. The labour demand for the production farms ranged from 61 to 253hha1 and from 194 to 396hLU1 (LU is livestock units) for work in the animal houses. Model validation results showed that farm managerial tasks amount to 14–19% of the total labour requirement. The impact of introducing new technologies and work methods related to organic farming was evaluated using two innovative examples of weed control: a weeding robot and an integrated system for band steaming. While these technologies increased the capital investment required, the labour demand was reduced by 83–85% in sugar beet and 60% in carrots, which would improve profitability by 72–85% if fully utilised. Profitability is reduced, if automation efforts result in insufficient weed removal compared to manual weeding. Specifically, the benefit gained by robotic weeding was sensitive to the weed intensity and the initial price of the equipment, but a weeding efficiency of under 25% is required to make it unprofitable. This approach demonstrates the feasibility of applying and testing operational models in organic farming systems in the continued evaluation and documentation of labour and machinery inputs

INTERGRATING PHYSICAL AND CULTURAL METHODS OF WEED CONTROL – EXAMPLES FROM EUROPEAN RESEARCH

The most recent advances in European research on non-chemical weed control methods and strategies for horticultural and agricultural crops are presented

Current European weed control methods and strategies against annual and perennial weeds in organic farming

Review of physical and cultural weed control methods for organic farmin

Organic farming at the farm level - Scenarioes for the future development

The purpose of this report is to present possible impacts of new technology and changes in legislation on the profitability of different types of organic farms. The aim is also to look at both the current and future trends in the organic area in Denmark. Besides the economic aspects, the report also shows the nutrient surplus for selected organic farms. Analyses carried out at the Food and Resource Economic Institute (FOI) have previ-ously shown that price premiums of up to 50% on pig meat and 20% on arable farm products is needed to make the organic production profitable. The price premium on cereals and dairy products have in the 1990’ties been higher than required, but in re-cent years the price premium has dropped, leading to low profitability, especially on arable farms. The organic farms in Denmark consist mainly of two types of farms, full time dairy farms and part time arable farms. The dairy farms constitute 25% of the farms, 50% of the area and they have 80% of the livestock units. The part-time arable farms con-stitute 60% of the farms, 28% of the organic area and they have 5% of the livestock units. Previous predictions made by FOI regarding more part-time farms converting to organic farming have been fulfilled, whereas the conversion to organic pig production has been much lower than expected. Both dairy and arable farms are facing new threats as the organic milk production is still much higher than the consumption, and as the profitability on small arable farms is low. The aim of the project is, therefore, to look at the impact of new technology on the profitability of organic farming. As organic farming in Denmark has experienced leg-islative changes leading to lower use of imported feedstuffs, it was also an aim to look at the impact of legislative changes, allowing only 100% organic feed, straw and ma-nure. To analyse this eight case farms were selected as typical organic farms. They con-sisted of 3 dairy farms, 4 arable farms and 1 pig farm. The area and the production on these case farms were based on interviews with local consultants, but they are not ac-tual farms found in Denmark. The intension was to present the typical future organic farm in terms of size, area and crop rotation. The yields and the machinery on these farms were determined in close co-operation with researchers at Danish Institute of Agricultural Sciences (Bygholm). The analyses regarding the profit shows on case farms a profit on the dairy and pig farms and a negative result on the arable case farms. This is comparable with net prof-its found nationally on organic farms in 2002. The capital invested in machinery on case farms is lower than found on actual organic farms due to the optimization proce-dure used to find the right level of machinery. The analyses also show that there does not seem to be significant differences in the machinery costs between conventional and organic farms. The analysis is based on 16 organic and 14 conventional study farms, which makes costs comparable. The ma-chinery costs on the case farms are in line with machinery costs on organic study farms, where most farms have costs between 3,000 and 7,000 DKK per ha (100 DKK = 13.4 €). The impact of new technology is analysed, focusing on the technologies which are found to be available in the near future and where the first trials look promising. The technologies analysed include robotic weeding, band streaming before sowing, use of GPS when applying animal manure and automatic milking using a robot. Both weed management technologies are found to be profitable and to be recommended for fur-ther development. The purpose is to remove weeds inside the row. GPS might give some economic benefits, but will be more profitable in a scenario with restrictions on nitrogen use. More trials have to be conducted to determine whether GPS is profit-able. Automatic milking is not a technology exclusive to the organic sector. The analyses show that if the capacity is well used it might be profitable. As a whole, the technologies do not seem to have a major impact on the future development in the or-ganic sector as the focus is on relatively specialised crops which cover a small area. For the technologies which can be used more widely, the improvement in income is limited. The difference between organic production and conventional farming has diminished over recent years as conventional farmers use less pesticide and mineral fertiliser. Furthermore, the European rules for organic farming might change. The possible im-pact of changes in legislation has, therefore, been analysed. The changes include the following restrictions: • 100% organic feed (requirement from 2005 on dairy farms) • 100% organic straw (no import of conventional straw) • 100% organic manure (no import of conventional manure) 100% organic feed has already been introduced for dairy farms in Denmark, whereas for pig farms it will increase feed costs by 10-17%, but the production will still be profitable. Using 100% organic straw will increase income on arable farms a little and lower the income on livestock farms with few cereal crop areas. The 100% organic manure scenario will reduce the manure (slurry and farm yard ma-nure) used in the organic sector by approximately 20% and increase the price from 5 to approximately 10 DKK per kg N. The effect is a decrease in application of 10 kg effective N per ha. The analyses show that dairy farms will increase their export and apply less than today, whereas arable farms will only reduce their N application a lit-tle. The loss in income among the arable farms is, in the calculation, almost the same as the gains made by the dairy farms, as the yield reductions are limited. However, in the analyses, it is expected that arable farms already today pay for manure imports, which is often not the case. This implies that the costs for organic arable farms found in this analysis under estimate the actual costs. This will also make it more difficult for con-ventional farms to export their manure. Another assumption is that transportation costs are minimal. However, this legislation will imply transportation of manure from livestock intensive areas to arable areas. The total cost of this is roughly estimated at 10-13 million DKK or 700-1,000 DKK per ha for the arable farms in Zealand which receive the manure. Alternatively, the arable farms would have to either have their own livestock or farm without the use of animal manure. The conclusion is that such a legislation will reduce the income on arable farms and increase the income on dairy farms and that it would lead to a change in the regional distribution of farms as livestock and arable farms would have to be located close to each other to reduce transportation costs. For dairy and arable farms located close to each other, such legislation would not necessarily lead to much lower profit for the farms seen as a whole as the animal manure might be utilised bet-ter. Whether the prices for agricultural products could increase in case where they are 100% organic, is questionable and is, therefore, not included in the calculation. In the last chapter, the nutrient balance is estimated on the case farms in the baseline and with a 100% organic manure scenario. The nutrient balance in the baseline shows a nitrogen surplus of 47-110 kg N per ha. The most difficult input to estimate is the N-fixation, which varies with yield and application of animal manure. The case farms have a phosphorus (P) surplus of around zero. For potassium (K) some farms have a surplus others a deficit of up to 90 kg K per ha. In the 100% organic manure scenario, the lower manure application affects the sur-plus more than the slightly lower yields, leading to lower N-surplus, P deficit and lar-ger K deficit than in the baseline scenario. It should be noted that attempts in terms of applying other P and K sources have not been included. The final chapter deals with conclusions and perspectives on the future of organic farming at the farm level. For the dairy farms, there needs to be a better balance be-tween production and demand. This will probably lead to a reduction in the amount of milk which is given the price premium by 30-40%. In the case where these farms stop as organic farms they will reduce the organic area by 30,000 ha. The organic area could therefore be reduced to 130,000 ha. With the lower organic area it is not likely that the organic milk production will exceed 10% of the total Danish milk production. However, it is also likely that farms which stop organic production will continue with an environmentally friendly production not using pesticides and with a limit on the nitrogen application. Many organic farmers have, over the years, come to appreciate this type of production. So although some might change back to conventional farm-ing, they will still use less pesticides than conventional farmers and use the crop rota-tion more actively in order to reduce N-leaching. A smaller organic dairy sector will make the 100% organic manure scenario more costly as the amount of organic ma-nure is lower. The small part time arable farms will probably carry on as the main income comes from outside farming. The challenge is to make efficient large arable farms profitable and in order to do so, they will have to be very large and be efficient. The trend will probably continue away from a subsidy for organic production and to-wards a subsidy for the environmental benefits. The current subsidy level in Denmark is not likely to be increased and the price premium seems to be declining. This indi-cates that the organic as well as the conventional farms will have to be more efficient to be profitable

Computational Contributions to the Automation of Agriculture

The purpose of this paper is to explore ways that computational advancements have enabled the complete automation of agriculture from start to finish. With a major need for agricultural advancements because of food and water shortages, some farmers have begun creating their own solutions to these problems. Primarily explored in this paper, however, are current research topics in the automation of agriculture. Digital agriculture is surveyed, focusing on ways that data collection can be beneficial. Additionally, self-driving technology is explored with emphasis on farming applications. Machine vision technology is also detailed, with specific application to weed management and harvesting of crops. Finally, the effects of automating agriculture are briefly considered, including labor, the environment, and direct effects on farmers

Analysis and Definition of the close-to-crop Area in Relation to Robotic Weeding

The objective of this paper is to analyse and define the field conditions close to the crop plants of sugar beet (Beta vulgaris L.). The aim is to use this study for the choice and development of new physical weeding methods to target weeds at individual plant scale level. It was found that the close to crop area is like a ring structure, comprising an area between an inner- and outer-circle around the sugar beet seedling. Physical weeding should not be applied to the area within the inner circle. The radius of the inner circle increases with the appearance of young beet leaves during the growth season. It was also found, that no weeds were germinating within 1 cm around individual sugar beet seedlings. Therefore this distance should be added to the radius of the inner circle. The space between the inner and outer circle is termed the close to crop area where physical weeding should be applied. The size of this area is defined by the developmental stage of the sugar beet fibrous root system and foliage. Thus, the determination of the growth stage of individual crop plants is necessary before any physical weeding can take place in the close to crop area. Uprooting, cutting between stem and root or damage of main shoot can do the physical control of most weed species located in the close to crop area. However, the targeting of weeds from above and from different angels above ground is limited in the close to crop area. This is caused by the fact that sugar beet leaves do not leave much space between leaves and ground and that our own study indicate that 26.4% of sugar beet plants at the 4-6 leaf stage are covering the main shoot of weeds. The most problematic weeds are the species, which have their main shoot and leaves located close to ground level. These species can either be controlled by damage of the main shoot or with a combination of shallow surface cutting and burial. Discrimination between weed species is beneficial under certain circumstances. First, the efficiency of the physical control of individual weed species is depending on the timing. Secondly some weeds species do not have significant negative impact on the yield, but instead leaving these species uncontrolled could benefit to an increased bio-diversity and reduced time and energy input for a physical weeding process. This paper is contributing to the ongoing Danish research project Robotic Weeding

Combining physical and cultural weed control with biological methods – prospects for integrated non-chemical weed management strategies

The paper deals with the possibilities of combining physical weed control with biological weed control

Recent results in the development of band steaming for intra-row weed control

The recent achievements with developing band-steaming techniques for intra-row weed control in vegetables are presente

Current achievements and future directions of physical weed control in Europe

This paper reviews major results achieved with physical weed control methods and strategies especially adapted for horticultural and agricultural crops. Mechanical methods, such as weed harrowing and inter-row hoeing, have provided promising results in cereals, pulse and oil seed rape, particularly when they are part of a strategy that also involves cultural methods such as fertiliser placement or crop seed vigour. In row crops, intra-row weeds constitute a major challenge, and research has mainly aimed at replacing laborious hand weeding with mechanization. A number of investigations have focussed on optimising the use of thermal and mechanical methods against intra-row weeds. And new methods are now under investigation such as robotic weeding for row crops with abundant spacing between individual plants and band-steaming for row crops developing dense crop stands