Pulse crops are a key part of crop rotations, increasing net returns and providing rotational benefits to subsequent crops.
Recent studies at Indian Head, Sask., show peas and lentils grown every other year in rotation with wheat can reduce the amount of inputs needed and help control weeds in the wheat crop.
Research by Doug Derksen of Agriculture Canada’s Brandon Research Centre is the first to show that pulses have a positive effect on subsequent crops, not only because they can fix nitrogen, but because they minimize weeds.
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The Brandon centre is working with the Saskatchewan Pulse Crop Development Board on a five-year study to better understand the reasons for rotational benefits from pulses. Researchers are taking a closer look at how weed management, nutrient dynamics, and soil and crop quality are affected by nitrogen fixed by peas versus nitrogen fertilizer.
The objectives are to find out which factors contribute to reducing weed problems and increasing net returns, and to what level inputs in wheat can be reduced before yield, quality and net returns are affected.
This study involves a team of Agriculture Canada scientists investigating several aspects: the effect of peas in rotation with wheat on changes in weed communities and herbicide use; nitrogen uptake and response in wheat; crop residues and soil physical properties related to water infiltration, soil fungi and bacteria; and the incidence of wheat and pea diseases.
Research sites were established in 1997 on a sandy loam and clay loam soil near the Brandon centre using high and low disturbance direct-seeding systems.
For each system, wheat is fertilized from 25 percent to 100 percent of soil test recommendations and herbicides are used at full and partial rates. This is done to help determine the effect of nitrogen on weed management.
Results from 1997 showed peas and wheat responded differently to the two seeding systems. Wheat yields were greater in the low-disturbance system at both sites, while pea yields were higher in the low-disturbance system on clay loam and in the high-disturbance system on sandy loam.
Crop establishment was better for both crops in the low-disturbance seeding system at both sites.
Scientists will be able to evaluate the performance of wheat and peas under different direct-seeding systems when they analyze this year’s harvest.
