What are weeds? 2 + 8 minute writing task
You have up to 2 minutes to read the following instruction carefully:
Task 11: Weeding is another strategy to manage oil palm plantations. Before we encounter (dis-/advantages) of different weeding methods, please write down your pre-knowledge on weeds.
You have approximately 8 minutes to write a. 1 paragraph in which you define shortly in your words what weeds are and give examples of weeds. b. 1-2 paragraphs in which you explain why they can be a disadvantage to crops.
Time is ticking. When 10 min are over the task is closed automatically.
Supplementary question: Which weeds might exist in oil palm plantation?
Hint: For an impression, you can have another look at the 360° tour.
Weeding: Ways to Battle Weeds
Task 12: Read the text “Ways to Control Weeds”. Imagine you work on an oil palm plantation. A new colleague says he has heard that chemical weeding with herbicides has environmental disadvantages. He asks what you know about possible advantages and disadvantages. List what you learn in the table below.
Herbicides to Control Weeds
In cultivation, certain weeds need to be stopped from competing with the desired crop. So, how can you battle weeds? The most used method is to applying chemical weeding. Generally, there are selective herbicides which control only very specific weed species, while leaving the desired crop relatively unharmed. There are also non-selective herbicides, which kill all plant material they come in contact with. Other important distinctions include timing of application, mechanisms of action, and methods of application. Most herbicides are applied as water- based sprays, using sprayers that vary in design and size.
The most used herbicide is glyphosate [27]. Although international assessments concluded that glyphosate does not represent a public concern and is neither toxic nor carcinogenic according to the current state of research, the use of herbicides is a controversial topic with heated discussions (comments on [28]). Generally, herbicides are regarded as effective and fast ways to kill unwanted plants even on closely planted crops [23].
They increase crop yield by decreasing competition with weeds for water, nutrients and light. Also, herbicides are said to increase economic benefits, as they are relatively cheap [29]. There might be health dangers for people working directly with herbicides. Due to the weeds' ability to adapt to the use of herbicides, resistance to chemicals is also given. Herbicides decrease ground vegetation and, therefore, reduce soil nutrient retention. Moreover, chemical herbicides contribute to water pollution. They pollute the soil where they have been applied and rainwater can also carry chemicals to other areas. Hence, some chemical herbicides end up in waterways, where they affect aquatic life..
Brush Cutters to Control Weeds?
Negative effects, such as nutrient leaching losses, can be reduced by using mechanical weeding [9]. Although there are several options for mechanical weeding, the most common one is to cut down ground vegetation with a brush cutter to a height of 1-2 cm. This does not have to be done more often than herbicide application, but it reduces leaching losses, and soil, as well as water pollution, compared to the conventional herbicide weeding [9]. As farmers need to pay workers to perform this, mechanical weeding is sometimes seen as the less economically profitable option.
Although there are hardly any long-term investigations, the implementation of mechanical weeding has not affected oil palm yield in experiments conducted so far [20].
Weeding: More Harm than Good?
Oil palm management practice 2: Chemical weeding (herbicides)
