Weed control in Organic Farming
Weed control in organic farming can be a tricky thing. For many years a majority of farmers have been using chemicals as their primary weed control method. While chemicals when properly applied offer great selective weed control they are beginning to have unexpected side effects in today's agriculture. There is a growing trend of herbicide resistant weeds that require stronger and stronger chemicals to effectively eradicate. This increasing use of herbicide is having a detrimental effect on the environment and ecosystems that it is applied on.
With these growing concerns about herbicides and their unexpected consequences more and more farmers are turning to organic weed control methods to manage weed populations. Now to effectively manage weeds without chemicals you have to be much more aware of your weeds growth patterns, habitat requirements, flowering dates and other information that would give you an edge in managing them. This information can be found in places like your state's extension website which is full of information both about weeds and crops you want to grow.
Now there are a few cultural practices a.k.a management techniques commonly used by organic farmers to reduce weed pressures on their crop lands.
Now I have talked about cover crops many times in other articles on this site mainly in the gardening and soil health section. But on the larger scale of organic farming they are also great tools in weed control along with the many other benefits they provide. How they work in a organic farm is simple but has multiple facets that will need to be covered. To understand how it works the first thing you have to know is that nature does not like monocultures or just one species of plant growing in a area. So nature tries to broaden a plant base in a field by sprinkling in its own additions. This is essentially why weeds pop up in your fields because they take advantage of gaps and holes in the vegetation cover.
Cover crops figure into this because they do a couple of things to suppress weeds in your fields. First they provide the plant diversity that mother nature loves so much. This diversity however can be controlled to your benefit since you can plant cover crops that can be successfully killed by temperature swings or by light cultivation of the field. Both of which are approved organic practices and can be done on organic farms. The second way cover crops work is that they occupy the field in the early and late parts of the growing season. This provides stiff competition with weeds that reduces their numbers and their growth success during those times between crops.
Other side benefits of covers crops would include nitrogen fixing, nutrient retention, organic matter additions to soil and improvements to soil health. These side benefits can also reduce weeds since it enables your desirable plants to better compete with weeds and will slowly push them out.
Cultivation has been in the tool bag of farmers since the beginning of agriculture some 10,000+ years ago. Recently we have become aware of the damage than can be caused by unrestricted cultivation on the land but that does not mean that cultivation in a limited way cannot be a useful tool. To better understand this you have to better understand the life cycle of a weed like plant. Now most plants that are considered weeds are annual plants that take advantage of the open bare soil of a crop field. The seeds that they produce are amazing in both the amount of seed produced but also with how quickly they germinate and grow. Weedy plants have evolved to be the first and the fastest to grow the moment it is warm and wet enough to germinate. This can give them a enormous competitive advantage over new growing crops as they can reach sunlight and take up nutrients and water faster than your crops can.
But this rapid immediate growth is what you can take advantage of with light cultivation. Allow the first flush of weeds to grow right up until a week or two before you plant your crops. They will have invested a lot of energy into that initially growth and you will attacking them when they are at their weakest. Cultivation at this point in the weeds lifecycle will be devastating to its success and by doing this you will destroy most of the weeds in your field. Now there will always be some that survive but you will have greatly reduced competition to your crop. The key to this technique is timing, you want the weedy plant to grow as much as it can, but you will want to kill it before it puts out any of its seed. By making sure to destroy the weeds before they can make seed you will over time reduce the seed load in your soil and you will have to deal with weeds less and less at time goes on.
A relatively recent addition to weed control in farming you can use a flamethrower that burns the tops of the weeds without disturbing your crop. This technique is very useful both before the crop emerges from the soil and for weeding between the rows. This particular method is still in the trial and error phase of its development so the success rate is variable. Some studies have shown a high mortality rate in broad leaf weeds while at the same time much less success with grassy species. This most likely has a lot to do with how those two groups of plants grow and there specific adaptations to fire. Much more study is needed to really nail down the effectiveness in the most common types of crops and the weed problems they suffer.
What we do know is that flaming can be more economical than other more traditional methods and has no after effects like pesticide residues and soil organic matter destruction. Flaming could become a very good tool in the weed control fight in the years to come and it will be something to pay attention to as time passes.
If I could sum up weed control in organic farms in one word I would that word is timing. Because like a lot of things in life weed control is a lot easier when you get your timing right. Proper timing of your cover crops and light cultivation can make a huge impact on the success of a organic operation. If you want to learn more there is lots of information available here on the Green Living Library and the internet in general. One of best resources will be your states university extension website that will be loaded with all sorts of information on agriculture, gardening and many other topics.
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