Staying alive long enough to multiply in the soil is the greatest challenge faced by a pulse seed rhizobium inoculant.
Plastic may be the answer.
An Alberta company has developed a new polymer product to keep rhizobium moist enough to survive on a seed for up to 21 days. This provides a longer application window for pulse crop producers who prefer to inoculate large batches of their seed.
The concept is not new to alfalfa growers, who have had the option to stick the nitrogen-fixing bacteria to their seed with polymers for several years, but it is new for lentil, pea and chickpea producers.
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GrowTec Inc. of Nisku, Alta., has two products it says increase the life expectancy of peat-based pulse crop inoculants, ProTec Max and ProTec UTA. ProTec Max is a commercial seed coating designed to hold and protect more of the rhizobium bacteria than water alone, while ProTec UTA is designed for the do-it-yourself farm inoculator.
The water-based polymer is applied using conventional strategies. In the seed plant it can be applied like other seed coatings while the UTA product replaces the water that is often sprayed onto seed in the auger or hopper.
“The product has been available in a limited way over the past couple of years and we have had a lot of success with it,” said Earl Greenough, of GrowTec.
Concerns that the product, because of its sticky nature, would accumulate on seeding equipment, have been unfounded because it dries quickly and is applied at rates of about four to five millilitres per kilogram of seed.
“We are seeing live cell counts of over a million cells per seed. The Agriculture Canada minimum for this type of product is 32,000 … that could be why we are seeing populations often 10 fold greater with the coating versus water,” said Greenough.
When applied on the farm, GrowTec says ProTec UTA will keep the bacteria alive for up to seven days.
“Long enough to accommodate most rain showers that usually follow inoculating a truck load of seed,” said Greenough.
Rain may not be the problem for pulse growers this year in much of the western Prairies where drought is a major threat.
But the product may also have advantages in preventing desiccation in the field.
“Farmers still need to be using the best possible practices to avoid desiccation of the inoculant,” said Greenough.
Ray McVicar, special crops specialist with Saskatchewan Agriculture, agrees.
“Anything that prolongs the life of the rhizobia is a welcome addition to the farmer’s arsenal for the field and if this works, great.”
McVicar said growers should make sure the inoculant and the seed it is going on does not get too warm.
“Light can be another thing to avoid, as it will kill inoculant. Keep the truck tarped and if you’re treating in the field, which is still the best place to do it, don’t store the bags of inoculant on the seat of a warm truck cab.”
The product can also be applied along with fungicides and other products, but in some cases these will lower the lifespan of the rhizobia, so the manufacturer’s recommendations need to be strictly followed.
The suggested retail price for the commercially applied product along with a peat inoculant is about $3 per bushel of pea or lentil seed treated.
UTA, the farm-applied coating, costs 80 cents a bu. without inoculant, which averages another $1.40 to $1.50 per bu.
