In this article: www.newfarm.org/depts/NFfield_trials/0705/weeds.shtml on weeds and crop competition, do you also study the types of weed growing and the effect different weeds have on the crop? Do some weeds attract more beneficial insects? Do some weeds supply better replacement minerals after tilling in? Can some be a kind of beneficial living mulch discouraging some pests and soil born infections? I am reading some books on weeds, why they grow, what they say about the soil and fertility of the soil, and how they can help bring good fertility levels back to neglected and depleted lands. But I was wondering about weeds as beneficial to the crop itself in an organic system and if anyone had done any study on it.

Thank you for your time,
Deborah Wright



Great questions all! Once again we turn to our organic weed control expert Matt Ryan. (Matt was the primary author on the piece you sited in your question.) Here’s what Matt had to say:

Thank you for your interest in our research at The Rodale Institute! Yes, we do study the diversity of weed species present in the experiment mentioned in the article. However, we do not study the effects of individual weed species on crop yields (we'll save that type of research for the land grant universities). This experiment was designed to evaluate the naturally occurring flora that encompasses multiple weed species. If you would like to see a summary of the work we have done on weed species diversity, please let me know.

The next part of your message seems to focus on the potential benefits that weeds may provide (correct me if I am wrong). Certainly, different weeds do different things, such as attracting beneficial insects, cycling nutrients, and stimulating crop growth. One of the issues people face when trying to retain beneficial weeds is that there are usually some bad weeds that come along for the ride.

You are right on target when you say that weeds can improve fertility levels in depleted soils, and it is a natural progression to ponder the potential benefits these weeds may provide to crops. While research has been done on this topic, it’s still in its infancy. One study looked at the effect of weeds on soil microorganisms and the potential for weeds to supply crops with beneficial microorganisms (Struz et al 2001). I have listed a few journal articles that you might be interested in below. If you are interested and cannot access them, please let me know and I will send you a copy of each.

I am hopefulthis answered you questions, but if I came up short let me know and we'll continue the discussion.

Matt Ryan

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Thank you so much for the articles you referenced—I have a lot to read and learn (about all things related to land)! Any actual doing of things has to wait until the house is done (only a few more months) and I am living up there. The study of how to use the land and its resources wisely is a good use of time, so I study. What I find usable will be in the providence of time and experience. Study will at least make any mistakes I make well educated ones! My intentions are good, so hopefully I will at least do no harm. ATTRA and SARE have also been good resources for environmentally sound and sustainable land use, as have the forums at New Farm and Organic Gardening magazine. The generous nature of people shines in the way so much information is so willingly shared.

Thanks again,
Deborah Wright

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