Inoculant may build up in the soil over time, but researchers who ran summer trials in Swift Current say that doesn’t mean we shouldn’t keep applying it
This summer, thanks to funding through the Agricultural Demons-tration of Practices and Technologies (ADOPT) program, three pea inoculant trials were conducted in Saskatchewan, at Swift Current, Scott, and Melfort.
While the Swift Current results are in, the final report has not yet been written up, which means results are preliminary and have not been fully analyzed. Bryan Nybo, manager of Wheatland Conservation Area, was willing to share some of the results, but is careful to note that this is the first year that the demonstration has been conducted and trials were not replicated. For this reason, he is not overly confident in making firm recommendations; however, he did say that some results were consistent with traditional findings for the region.
Swift Current trials
Besides being un-replicated, the trials had a few other things working against them last summer, namely weather. Although they had a really good start to the year, an early hailstorm on June 24 created some unexpected damage. “We had higher than average rainfall from April, May and June,” says Nybo. “And then that was followed by July, August and September, which were the driest three consecutive months that have ever been recorded in Swift Current.”
Products were demonstrated in 13 separate trials using peat, liquid and granular inoculants by Tag Team, Cell Tech, Pulse Signal II/Optimize and Nodulator. In one trial, no inoculant was used, but nitrogen was added instead. In the last trial, peas were grown without inoculant or nitrogen. Of the 13 trials, yields ranged from 31 to 26 bushels per acre. Consistent with expectations, the peas that were not inoculated and grown without nitrogen came in second from the bottom.
“So there’s still a need for inoculants on pulses in this area for sure,” says Nybo. “Traditionally, in this area we’ve found the granular inoculant still to be the best. Sometimes the peats are as good as the granular. In other years, they’re just a little below. Again, the long-term traditional results in this area, the liquids — some years they do good, but other years they don’t tend to do quite as well. They seem to die off a little earlier than some of the other inoculants.”
Nitrogen vs. inoculant
Interestingly, the peas that received no inoculant, but nitrogen instead, fared quite well. In fact, they came in second on the list. Brad White, an agrologist with South West Terminal at Gull Lake, said they tried nitrogen on its own just to see what it would do.
“Actually,” he says, “It was every bit as good as. Between the little bit of inoculant that came out of the soil, and the nitrogen that was provided there, the yield was actually the second best in the whole trial. But 60 pounds of nitrogen is going to cost a guy $35 to $40 an acre, whereas your seed-applied inoculants will be down to $5, and your granular inoculants are $10 to $15, so it’s quite a bit more money.”
Nitrogen, he says, is a bit of a relief as an option, since the use of insecticide reduces the survivability of inoculants. And, unfortunately, with an escalating pea leaf weevil problem, foregoing insecticide really isn’t an option.
“If we keep seeing a lot of issues with these pea leaf weevils chewing all the nodules off and reducing the plant’s ability to make nitrogen, and therefore, yield, well, is it going to make more sense to just fertilize these things?” asks White. “I would assume that most guys would not plant them if they get that bad, but if peas are worth $10 or $12 per bushel, you’re going to grow them.”
After a number of years, some inoculant will survive over the winter and build up in the soil, affecting the pulse crop in the following year. White is careful to note that this does not mean that farmers can stop using inoculants altogether.
“The issue here is that there’s no way to figure out if it’s over-wintering,” he says. “Just because it overwintered for the past year, it might not survive in a colder year. You have no idea how much, if any, survived. That’s why you always want to put some commercial inoculant on your seed.”
Choosing a product
On his own farm, White used Tag Team for a number of years, but recently switched to Nodulator. He wanted to see if something else would give him higher yields.
While higher yields are what most farmers are looking for, some have different reasons for switching products. Randy Taylor, a farmer at Gull Lake, has been using both Tag Team and Nodulator.
“I started out with the peat-based stuff years ago, and then I went to the granular-based for probably the last almost 10 years,” he says. The reason for the switch had nothing to do with yields, though. Taylor claims that as far as he can tell, both products work equally well. He switched to Nodulator simply because he found it more user-friendly.
“Nodulator — they were the first to come out with the mini-bulk bag, and I really like them,” he says. “Instead of messing around with the little 60 pound bags, I think they’re 800 pounds and they do about 160 acres.”
“Before they came out with those mini-bulk bags, well, where I farm, there’s lots of wind. Trying to get the bags in the grain truck took two or three guys to put a day’s worth of inoculant in. Bags are blowing all over the country…” And, he says, the peat-based products left the inside of his grain tank dirty.
The final Swift Current results, as well as those for Melfort and Scott, should be ready soon. †