February 1999
Don't we hate them - weeds - in the field, in the garden, along the road. From the bible and throughout times, humankind tried to rule over the planet and all life. Today, popular thinking, with the advertizing help of the herbicide manufacturers, has us doing everything we can to eradicate weeds. "Look at the neighbour's clean field" he says. But I ask: what is the point and how much did it cost?
We spray our lawns, the roadsides, and our fields. Does it work? Of course not! If it did, we would have solved the problem by now and not needed any more sprays. You may answer that the situation would be worse without sprays. With current agricultural practices, you are probably right; but the point is that there are other ways to farm that are less expensive and less toxic to you and the environment. Secondly, sprays only hit the growing plants, not the millions of seeds still in the soil, ready to come back next year. We throw a lot of money at weeds, the never ending battle, but we invest little effort in understanding the role, propagation and management of weeds.
Ecological and organic farmers have made a firm decision to avoid herbicides. Then the paradigm shifts; the mind opens up to a whole new range of possibilities in weed management. The first issue is tolerance. True, weeds compete with desirable plants for nutrients. But there must be a lot of weeds for the competition to affect yield. With proper tillage, soil conditions and fertility, the crop usually has the upper hand and the organic farmer can tolerate a reasonable weed population.
Secondly, weeds can be beneficial. Dandelions are extremely nutritious and tasty in the form of a salad or a wine. In field crops and especially row crops, weeds break up the crust, let the rain into the soil, reduce runoff and erosion, protect the soil from the hot sun and sometimes complement the desired crop in a symbiotic way as we would under seed cereals with hay.
A weed, like any desirable plant, will thrive and propagate in its own preferred and often unique conditions. The organic farmer will identify the weeds on the farm, understand the ideal growing conditions for each weed and then recognize those conditions where each weed is growing. Let's face it: the seeds are there. If the conditions are right, the weeds will grow; so change the conditions to favour the desired crop and not the weeds. The organic farmer will manage the crop rotation and the soil amendments to change the growing conditions and thus prevent the weed from growing. Sprays would try to eradicate the weed without solving the problem, like giving a pain killer to a patient without fixing the wound.
Soil compaction will favour grasses. Ragweed loves a high nitrogen level. Wild mustard sprouts in the surface crust of a cold soil. Some plants like a high or low PH. Others want dry or wet conditions and so on for poor soils, mineral imbalances, etc. Unfortunately, conventional farming today tends to create those very conditions. Hence the phrase: weeds are created not controlled. We do all the wrong things to our soil to the benefit of weeds and then spend lots of money trying to control weeds.
The informed farmer will try to time the tillage and planting for the ideal soil temperature and moisture content that will favour the crop instead of the weeds. That means resisting the temptation to get on the field as early as the neighbour. He/she uses smaller equipment and appropriate tillage to minimize and correct compaction. Calcium content, PH balance and organic matter are closely monitored and corrected with crop rotations and acceptable non-toxic amendments. Tillage is a big weed management tool with proper plowing, pre- and post-emergence harrowing using finger weeders, tine weeders, rotary hoes and the ordinary cultivator.
Crop rotation is key to improving soil conditions and managing weeds. Buckwheat will compete well and smother out most weeds while generating a cash income and improving the mineral availability for the next crop. Oil radish, even as a fall cover crop, will break through compaction and create good loose soil for soybeans the next year. Rye has a proven allelopathic effect; by releasing certain acids from the plant and residue, it inhibits the root and shoot growth of lambsquarter and pigweed.
And at the end of the day, the seed cleaner will remove the weed seeds from the harvest.
A contribution by Tom Manley
President of Homestead Organics