Autonomous weeders for Christmas tree plantations - a feasibility study
5 Specification of stakeholder requirements
| 5.1 | The current level of satisfaction with spraying and mechanical weeding technology |
| 5.2 | Stakeholder requirements to an ACW |
| 5.3 | Sub conclusion |
Frans Theilby
The Danish Forest and Landscape Institute, Department of Forestry
Spyros Fountas and Henning Nielsen
The Royal Veterinary and Agricultural University, Section for AgroTechnology
An important part of developing new technology is to define the desires or requirements of stakeholders, i.e. the future growers, operators, manufacturers and maintainers of the system. Those users know the circumstances under which the system should work as well as the function and shortcomings of present systems. They are also the people that have to live with the new system and its properties in relation to people, work tasks and the environment.
To get a good basis for the development work a workshop was organised with the project team and representatives from important stakeholder categories on the 5th of March 2001. The participants contributed with presentations on various aspects of Christmas tree production and on ideas in relation to development of an autonomous Christmas tree plantation (ACW). After this a brainstorm session was arranged to identify the current level of satisfaction with spraying and mechanical weeding as well as a specification of stakeholder requirements and wishes for an ACW. The main outcome of this process is reported in the following.
5.1 The current level of satisfaction with spraying and mechanical weeding technology
Weeding in the plantations is primarily done to reduce the direct competition for water, nutrients and light; however heavy weeds in Christmas tree productions can also lead to wear damages, which are deteriorating to the quality of the trees. Furthermore, various weed species which are deeply rooted in the plantation can restrain or even totally ruin a Christmas tree plantation. In general the need for weeding is greatest in the phase of establishing the plantation to secure survival.
Approximately 70% of the producers are using chemical weed control to some extent. Especially when using system 1, which mainly is used within field plantations, the use of chemical control is widespread.
Among growers the general attitude is that it is desirable to introduce more environmentally compatible weed control methods, if these also technically, economically and effectively are alternatives. The use of chemical weed control, especially the use of chemical soil weed control, has been strongly reduced in the recent years. The improvement in spreading techniques, e.g. band spraying and screened spraying, has also contributed to a reduction of the use of pesticides.
A political wish to reduce the use of pesticides has also contributed to the introduction of various alternative weeding methods such as mechanical weed control and weed control with animals. These methods are currently being improved and refined, but in general they are still too expensive. The cost of these alternative methods are 10-100% higher than spraying. At a time with decreasing income per tree produced it is only natural if the producers are trying to avoid increasing production costs, including weed control costs.
In general it is not the quality of the alternative weed control methods that is the main problem, but the higher requirement of manpower that these methods imply.
5.2 Stakeholder requirements to an ACW
In the project stakeholder requirements were specified on the basis of a workshop with participants from the various stakeholder categories:
Requirements:
 | Costs should be at most at the same level as chemical weed control |
| Able to work on steep gradients and irregular soil surfaces |
| Able to carry different tools, e.g. weed cutter and tillage tools |
| Safe in relation to humans and animals |
| Less than 5% trees damaged |
| Simple ACW transport |
| Easy maintenance (standard spare parts) |
| Secured against theft |
| Able to record important properties of trees and plantation |
Wishes of additional work tasks:
| Basal pruning |
| Fertilizer application |
| Spot spraying |
| Tree marking for sale |
| Shape regulation |
| Growth regulation |
| Transport of equipment for production measurements |
| Recording of tree properties for management and on line sale purposes |
| Selective planting of new trees |
| Selective tree felling (and possibly transport trees to a field handling point) |
| Selective replanting |
| Spatially selective processing according to needs. |
In relation to the development stakeholders indicated that it is essential to get clarification about:
| The frequency of treatment |
| The appropriate periods of treatment (from the middle of May, the beginning of July should be avoided for bud breaking reasons) |
| The possibility of combining different working operations. |
5.3 Sub conclusion
The stakeholders found it desirable to introduce autonomous technology for mechanical weeding in order to reduces environmental effects and labour requirements, but this new technology should be competitive to the present methods. Also the stakeholders were interested in autonomous machines for a number of other work tasks.