Lack of phosphorus is frequently the most limiting nutrient in alfalfa production in Western Canada, reducing yield, quality and longevity of the crops.
A recent study has found an inoculant called Provide can help make more phosphorus available, but it is not a substitute for a long-term phosphorus-fertilization program. The project supported by Saskatchewan Agriculture looked at Provide, a microbial seed inoculant registered for use on wheat, canola, mustard, field peas, lentil and alfalfa.
“We found that inoculation of alfalfa seed with Provide can make available the equivalent of 15 to 20 pounds per acre of phosphate fertilizer,” said Hugh Beckie, research scientist with the Agriculture Canada Research Centre in Saskatoon.
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The goal was to determine the growth, yield and phosphorus uptake-response of alfalfa to inoculation with Provide at different rates of phosphorus fertilizer across a range of soil and environmental conditions, and to calculate the fertilizer-replacement value of the inoculant.
Provide consists of spores of a naturally occurring soil fungus that can increase the availability of fertilizer and soil phosphorus to crops during the growing season. Soil at the test sites in the dark brown, black and grey soil zones contained low to medium levels of available phosphorus.
Alfalfa seed inoculation during the tests, which were conducted from 1994 to 1996, increased yields and phosphorus uptake in the establishment year by three to 26 percent.
“There was a small residual yield benefit in the year following establishment. Although results of this study indicate that Provide aids phosphorus utilization efficiency, it is not a substitute for a long-term phosphorus-fertilization program,” said Beckie.
Replacing fertilizer with inoculant could affect the economics of an alfalfa crop, but this will depend on the cost and effectiveness of the inoculant compared to that of the phosphorus.
He said society also views the use of biological products, such as inoculants, as more environmentally acceptable than fertilizer.
– Saskatchewan Agriculture
