Farmers Need Diverse Rotations
EDMONTON - Mar 1/18 - SNS -- Diverse crop rotations are the best way farmers can improve their bottom line, reduce future grief, and lower the risks of pests, disease and weeds, reminds Alberta's agriculture department.
"A good crop rotation is one where there is an adequate variety of crops grown so that any one type of crop is grown only once every three or four years," says Harry Brook, crop specialist at the Ag-Info Centre. "A rotation like this can reduce pest costs, prolong the usefulness of pest control products, and improve the bottom line. Limiting or shortening the rotation may provide short-term financial benefits but in the long-term, could severely limit future cropping "."
One example that Brooks uses is clubroot. "It converts the canola root into a massive spore factory. Its only spread in infected soils, but each year we see it in more Alberta fields. Once you have clubroot, its there for the long haul. These soil borne spores can remain viable in the soil for up to 20 years. If you have it, many counties will require the land be put on a four-or-five year canola-free crop rotation. However, resistance in a crop is not helped when the crop rotation is just wheat followed by canola."
A variety of crop types can add to the health of the soil. "Pulses in a rotation improves soil health and reduces fertilizer costs," adds Brook. "Peas, lentils, and faba beans all capture nitrogen from the air and encourage beneficial bacteria and fungi that can benefit following crops. There is a nitrogen benefit left in the soil that extends up to three years after the pulse crop."
"Permanent forages in the crop rotation provide even more benefits," Brook mentions. "They reduce the weed seeds present in the soil, increase organic matter, and are an excellent break for crop diseases and insect pests. Also, a varied crop rotation can help diversify a farm operation, reducing financial risk. It also spreads out machinery use, making them more efficient."
Moisture use efficiency also improves with a varied crop rotation. "Canola, wheat, and peas all root to different depths and extract moisture from different parts of the soil. A planned crop rotation can utilize soil moisture more efficiently. Permanent forages in rotation can also address soil problem such as soil salinity or acidity. Seeded in a field for three to five years, they are an excellent break from annual crops and add to the soil organic matter, which is your soil nutrient bank account. They can even reclaim some soils from salinity, over time."
"A diverse crop rotation also naturally varies the pesticides used and reduces the chance of resistance developing to pest control products," adds Brook. "Conversely, a tight rotation can quickly develop weed, insect or disease problems, requiring greater expense to control the issue. In the case of clubroot of canola, the only answer is resistant varieties, and that tolerance has already broken down."