LETHBRIDGE – Spreading the workload is a big issue on prairie farms as producers try to find enough time for field preparation and seeding in the spring.
Rob Dunn, a conservation cropping specialist with Alberta Agriculture in Lethbridge, says earlier seeding dates can help solve the problem.
He said farmers in southern Alberta probably have a 10 day planting window in which they would like to seed all their crops. However, equipment, labour and time constraints can conspire to make that an elusive dream.
Dunn said earlier planting dates allow crops to make more efficient use of water. If the crop can reduce the amount of water lost by evaporation, he added, more is available for transpiration and crop growth.
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“We’re also trying to avoid heat and drought stress at the critical growth stages, typically at flowering,” he said. “Some crops will tolerate that more than others. We also have a longer vegetative and grain filling period, which is particularly important for cereal crops. It gives us more yield potential.”
While each crop has its own optimum seeding time, Dunn said planting earlier in the acceptable window is usually the best.
“There’s a gradual yield decline when we have a one or two week delay after that optimum time. There’s a more rapid decline with a three week delay.”
Dunn said studies conducted in Swift Current, Sask., looked at the effect of seeding 10 days earlier and 10 days later than the optimum seeding date.
Yields increased in all crops when seeded early compared to a mid-May seeding date: spring wheat six percent; field peas three percent; lentils four percent; desi chickpeas five percent; Argentine canola 13 percent; Polish canola six percent and yellow mustard 22 percent.
Yields declined across the board when crops were seeded 10 days later than the optimum seeding date: spring wheat five percent; field peas 16 percent; lentils 23 percent; desi chickpeas nine percent; Argentine canola six percent; Polish canola 24 percent and yellow mustard 17 percent.
“Wheat was one of the least affected, while something like canola and yellow mustard, there’s a tremendous benefit to early planting.”
Dunn said results from research in Saskatchewan and Alberta confirm the effect of delayed seeding with mustard crops.
At Scott, yellow mustard yields declined 32 percent when seeding was delayed four weeks. Southern Alberta mustard yields declined by 37 percent when seeding was delayed three to four weeks.
Recent barley trials showed three week planting delays reduced malting barley yields in southern Alberta by 20 percent. Losses were greater when drought stress was severe.
In central Alberta, yields were reduced by 47 percent when seeding was delayed by five to six weeks, with more pronounced declines for later maturing varieties.
Chickpea yield reductions that resulted from later planting dates were 10 percent in southern Saskatchewan, 30 percent in central Montana and 20 percent in southern Alberta.
Dunn said recent trials in Lethbridge found that winter wheat yields dropped 18 percent and winter triticale yields dropped 11 percent when the crops were planted three weeks after the optimum date.
Delayed planting reduced emergence, winter survival and spring plant density.
While most crops can be seeded when the soil temperature reaches 5 C, Dunn said heat loving crops such as kabuli chickpeas, corn and sunflowers need temperatures closer to 10 C to initiate germination.
Knowing the effects of delayed planting on various crops can help farmers make more effective seeding decisions. Dunn said spring wheat is less affected, while peas, yellow mustard and canola are most affected by planting delays.
Peas or cereals are more suited to early seeding than oilseeds because they have less risk for post emergent frost injury.
If barley and wheat are both seeded, it may work better to plant barley before wheat to help spread the workload at harvest.
