Organic weed control

Photo submitted by Michael Ferrell

Little Bent Farm practices organic methods of weeding.

Who loves weeding? Getting rid of weeds is probably one of the most challenging aspects of gardening or farming. Eliminating weeds is time consuming, but necessary, because if neglected, weeds will take over your garden rows and rob your plants and flowers of essential nutrients and space. Weeds also harbor insects and plant pathogens, which will greatly reduce yields and negatively impact the quality of your garden. There are three important methods, used by Little Bent Farm, to minimize weeds, soil contamination, and erosion. These methods are soil solarization, soil amending, crop rotation, and cover crops. These methods are a healthy alternative to using chemicals or spending hours of time in backbreaking weeding and are easy to implement in your own garden or market farm.

Soil solarization (solar heating of the soil) is a method of plant bed preparation that we use here, at Little Bent Farm. It is an environmentally friendly method of using solar power for controlling pests, along with weed seeds and weed seedlings in the soil. By water soaking the soil and covering beds with a transparent polyethylene cover, the heat from the sun is trapped and creates steam. The soil is decontaminated and mulched as plant matter breaks down and soil-borne bacteria are destroyed. Soil solarization also speeds up the breakdown of organic material in the soil, often resulting in the added benefit of release of soluble nutrients such as nitrogen, calcium, magnesium, potassium, and fulvic acid, making them more available to plants. The heated soil is enriched, while undesirable plant matter dies down. This not only creates less work in preparing the beds for planting by destroying established weeds, it lessens the chance of weeds surfacing during vegetable growth and creates healthy habitat for worms that further nourish the soil.

Anytime you disturb the soil, you're going to bring up weed seeds. We try to always amend the soil and form the beds prior to solarizing so that when it's time to plant, we pull off the covers, allow the soil to dry a bit and very minimally disturb the soil surface when we plant. It is our goal to be able to do this to all our beds and completely transition away from using mulches, which must be replaced every year. This is our first summer growing season at the new farm and there are still a lot of weeds to be dealt with, but we can already see a difference in the areas that were solarized last fall verses the ones that were not.

Since soil solarization really came into its own in the 1970's with research by the scientists at the University of California. It leaves no toxic residue and can be easily used on a small-scale or large-scale garden or farm. Additionally, the need for labor-intensive weed prevention is eliminated. Plants often grow faster and produce both higher and better-quality yields when grown in solarized soil. This can be attributed to improved weed control, decontamination of the soil, the increase in soluble nutrients, and relatively greater proportions of helpful soil microorganisms.

Basically, the benefits of solarization to your soil occur within the top 6-10 inches of your beds, and the process takes 4-6 weeks (unless this is done in a growing tunnel, where the process can be accomplished in days), and should be attempted once the hottest months in your area begin. North/South bed orientation works best on a farming scale. Clear plastic works best for this type of application. Your plastic should be larger than the area you plan to solarize. The area needs to be dampened and then the plastic spread out, with the perimeter edges buried. This method preserves the soil temperature. Check the plastic routinely for holes or tears and be careful during removal so that you don't pull in soil from outside your decontaminated area. Make sure it is treated to withstand UV rays; otherwise you'll end up with little pieces of plastic in your garden. You can pick up agricultural grade polyethylene at farm supply and home improvement stores.

Soil amending is the next big bed preparation step we do at Little Bent Farm. Our chosen method for soil amending consists of green "manure", which is organic plant material that we compost. We never use animal manure or chemicals. You can amend your bed by tilling in compost or green manure, which will also re-introduce beneficial organisms back into the soil. We amend our growing beds with new organic green manure every six to eight months.

Crop rotation is another important method of weed control. By planting a different crop every year, you ensure that vitamins and minerals are increased in the soil, and not depleted like they would be by growing the same crop over and over. It also helps with soil erosion, soil stability, and pest control. We usually use "root & shoot" rotation crops such as peas or beans, and turnips followed by tomatoes and eggplant, which really increase soil stability, when combined with soil amending, by creating soil density. Root crops help to prevent soil compaction and loosen the soil and usually require different nutrients than "shoot" crops. After a root crop we use quick cover crops such as buckwheat that is cut and used as a green manure. This adds nitrogen and encourages healthy soil biota to ready the area for a shoot crop such as tomatoes, eggplants and corn. In addition, by rotating crops, weeds are systematically crowded out and dramatically diminished prior to planting.

Lastly, cover crops are an essential step in long term weed control and erosion problems, in between plantings. Little Bent Farm typically uses buckwheat crops as cover crops, because it is extremely fast growing and crowds out weeds because of its dense growth. It also imparts necessary levels of nitrogen back into the soil. After its growing cycle is complete, we cut it down and allow it to compost. We then use that in our soil amending as green manure or use as mulch in trouble areas.

These methods of soil preparation are safe and have been adopted by farmers in over 50 countries, who wish to responsibly grow organic crops. Soil solarization may sound complicated but it is simple to use and can be used in small beds grown by homeowners who wish to reduce weeding and chemical use, on a farm scale, all the way up to commercial scale of crop production. If you wish to learn more, there are many informative articles online or our local extension office can also help you get started. And of course, we are always happy to answer individual questions, if you reach out to us via our Facebook page.

It is Little Bent Farm's goal to not only provide delicious organic produce to our customers, but to help nourish a healthy environment by using long-term, responsible and sustainable farming methods. We also want to help educate our community. Responsible, chemical-free growing is something that everyone can learn and do. It's never too late to start.

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