A newer, early maturing variety makes the crop more attractive than it once was, but there are still agronomic unknowns
Black bean is not a common crop on the Prairies, but it’s getting increasing interest from farms under heavy aphanomyces pressure in their peas and lentils.
Black beans were not a viable option for most prairie growers until CDC Blackstrap became available, which has early maturity, can be seeded with an air seeder for narrow-row production, has higher pod clearance and is a good fit for both dryland and irrigation production.
However, there are some agronomic unknowns when it comes to growing Blackstrap.
Black beans are not as efficient as many of their pulse cousins at fixing atmospheric nitrogen, and Blackstrap is no exception.
This is even more of an issue because effective inoculums for the crop are not available in Canada.
Garry Hnatowich, research director at the Irrigation Crop Diversification Corp. in Outlook, Sask., led a study that showed a complete inoculate failure of the available inoculants for CDC Blackstrap.
However, most commercial black bean production around the world does not use inoculants and relies on nitrogen fertilizer.
Chris Holzapfel of the Indian Head Agricultural Research Foundation (IHARF) led a 2020 study into Blackstrap’s response to nitrogen fertilizer rate in dryland, solid-seeded production.
The black bean study had Saskatchewan plots in Indian Head, Melfort, Redvers, and Yorkton.
“We just really wanted to develop some nitrogen response curves for dry bean, simple as that,” Holzapfel said.
“A secondary objective was just to get some more information in terms of how this crop can actually produce under dryland production throughout the black soil zone in Saskatchewan.”
There were six nitrogen treatments in the study, including an unfertilized control, 45, 75, 105, 135, and 165 kilograms of nitrogen per hectare (soil residual plus fertilizer) with side-banded urea as the primary nitrogen source. In pounds per acre, that’s 40.2, 66.9, 93.7, 120.4 and 147.2.
The only nitrogen available to the crop in the control was provided by the soil and monoammonium phosphate (11-52-0).
A target rate of 40 viable seeds per sq. metre was used and the seed was placed at least three centimetres deep.
The plots were rolled after seeding and weeds were controlled using registered pre-emergent and in-crop herbicides with supplemental hand weeding where required.
Fungicides were applied to suppress sclerotinia and other leaf diseases at the discretion of individual site managers and pre-harvest herbicides were used as required to assist with crop dry-down and provide late-season weed control.
The focus of the study was on grain yield. It was dry in 2020 at three out of four plot locations and the yield was less than a tonne per hectare. However, Redvers achieved approximately 1.5 tonnes per hectare.
“But all of the sites for the most part, despite the low yields, did respond really well to nitrogen fertilizer. It was actually linear at three out of four of the locations, where basically yields kept climbing right up to that highest N rate,” Holzapfel said.
“Indian Head was an exception where we tapered off at a fairly modest rate somewhere around 75 kilograms per hectare. That’s a little bit over 60 lb. per acre that it works out to.”
He said he’s reluctant to recommend that growers apply nitrogen at the high rates in the study, but said the study does show that Blackstrap needs nitrogen and it responds well to it.
“You certainly do need to apply some nitrogen, and I guess it’s not going to be an insubstantial amount. You’re probably up around that ballpark area of 100 lb. per acre or higher,” Holzapfel said.
“But it is pretty early to tell. We don’t have a lot of experience with the crop. It would be nice to see if under better growing conditions, whether that response would be even stronger. It’s hard to know for sure.”
He said Blackstrap is much better when it comes to drought tolerance compared to some of its predecessors or alternative dry bean varieties, but it still needs a fair amount of rain.
“The other big thing I think is that it’s fairly well-suited to straight combine… I wouldn’t call them easy to straight combine, but we were in pretty dry conditions. It’s comparable to some of our other pulse crops. If you’ve got a flex header you can do it,” Holzapfel said.
He said the research group has applied to perform the study again in 2021.