Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).
Ron Morse. Virginia Tech. Blacksburg, VA.
It’s an interesting thing for me how I got into organic no-till. I’ve been doing what I label sustainable no-till for 26 years, but about 5 or 6 years ago, I started to become very much aware that many people who attended my talks were intrigued because of the weed control I was able to get with these high residue systems. If you get enough tonnage, 2-3 tons is kind of a minimum, you can suppress weeds. That doesn’t mean that there won’t be any weeds. But there is a concept that is very important and that is this minimum weed free period, which is the time that the field needs to be relatively clean before canopy closure. And with these heavy residues, we can achieve that. Especially with vegetable crops that have a quick canopy closure like broccoli. A major reason why high-residue systems are being used is it tends to amplify or enhance all the benefits of low-residue systems. Key examples would be weed suppression and the build-up and improvement of soil quality.
Proper selection, establishment and production of high-residue cover crops is the key to organic no-till. An ideal cover crop is moderately priced, easily established, you must be able to establish it without difficulty; highly productive, which means, a lot of biomass or residues produced; easily killed mechanically, which of course is required by organics, and lastly, is not allelopathic to the cash crop. It’s fine to be allelopathic to the weeds, but it can’t be allelopathic or interfere with crop growth.
Cover crops can be and normally are crop specific. One is cereal rye bi-culture with hairy vetch. This can be used successfully for fruit crops like tomatoes, peppers, and pumpkins it is widely used. Another combination is foxtail millet and soybean or foxtail millet and cowpea. Other people have used different millets. I tend to use foxtail, but other people prefer Japanese and some even pearl. The millets work really good, they produce a huge amount of biomass in a short time. They work really well as summer cover crops in preparation to receive fall broccoli or cabbage. Another thing that I found is crimson clover and barley. You can get huge amounts of biomass and nitrogen from crimson clover and it will come in earlier, like 3 weeks or more earlier, than hairy vetch. So you can use this for your early summer crops and we’ve been very successful.