Some Useful Research Highlights From the Indian Head Agricultural Research Foundation

By Geoff Geddes

Soybean farmers can harness the latest research to help them battle the elements and give their seeds a fighting chance.

A leading source of such research is the Indian Head Agricultural Research Foundation (IHARF), a non-profit organization based in Saskatchewan whose mission is to promote profitable and sustainable agriculture by facilitating research and technology transfer. Over the years, IHARF has pursued many research activities relevant to Western Canadian growing conditions. To complete these activities, IHARF manages both a small-plot research and demonstration program as well as a field-scale program on 1,200 acres of land cropped by IHARF every year.

“To be successful in the long run, you need to stay on the cutting edge of research,” said Chris Holzapfel, Research Manager for the foundation. “That’s why we focus on factors that are within the farmer’s control and give them the greatest chance for success.”

Here are some factors in growing soybeans that IHARF has been researching and what conclusions they have come to or are working on.

A space in the crowd

“Soybeans appear to be relatively insensitive to row spacing,” said Holzapfel. “In 2014, we actually saw yields increase with increasing row spacing. But in hindsight, our granular inoculant rate was limiting and this was likely a confounding factor. In 2015, the results favoured the 10- to 12-inch row spacing, although soybeans still performed quite well and managed to fill in the canopy right up to 24-inch spacing.”

Health before wealth

Currently, most of the foundation’s soybeans are planted into fields that are new to this crop, making proper inoculation critical.

“We have always used seed treated with liquid inoculant but require at least a full rate of granular inoculant on top of that,” said Holzapfel. “In some years, particularly under less favourable conditions (i.e. 2014), soybean yields continued to climb with increasing granular inoculant rates of up to at least twice the label-recommended rate.”Having said that, he stressed that one can’t overlook the law of diminishing returns.“Once growers have gone through a couple of cycles of soybeans in their rotations, the benefits to dual inoculation or rates exceeding label recommendations are likely to diminish. Research in Manitoba.

Because soybeans require a long growing season and are typically the last of the crops harvested in Western Canada, growers might be tempted to seed early. According to Holzapfel, it’s one temptation they’d be wise to resist.

is showing this to be the case there. In 2014, we also had a very strong response to N fertilizer application and we are doing more in-depth research on this matter now; however, I don’t expect to see a benefit to N fertilization under most conditions based on work that has been done elsewhere.”

The rate debate

What is the optimal seeding rate for soybeans? To some extent, it will depend on who you ask and when you’re asking, but there is agreement on general guidelines.

“In 2014 we had an extremely strong response to seeding rate, but yields were low and the highest rates would not likely have been economical. Preliminary inspection of 2015 results suggests that yields were leveling off at more modest rates in that year. At the same time, higher plant populations may result in taller plants (and pods that are higher off the ground and therefore easier to harvest) in addition to promoting earlier maturity, which is important in our environment.”

Currently, Holzapfel is recommending at least 200-220K seeds/acre, which is in line with the recommendations that industry had established before Chris and his team began their work.

Taking their place

Sometimes, it pays to be shallow. While there are exceptions, soybeans generally do not require deep seeding in spite of their relatively large seed size.

“We are looking at either 0.75” or 1.5” seeding depths and, although there haven’t been any major agronomic differences between the treatments, shallower seeding will generally result in more rapid and uniform emergence and an overall smoother seedbed.”

Not only is it unnecessary to use deep seed placement for soybeans; it can actually be harmful.

“Field peas have traditionally been our most important pulse crop in this region and many growers will seed this crop quite deep (i.e. >=1.5”) to ensure that it is in moisture long enough to germinate and get out of the ground. This does not appear to be necessary for soybeans and seeding too deep can delay emergence, increase seedling mortality and, perhaps, result in lower pods that are more difficult to harvest.”

Holzapfel acknowledged that you may want to seed a bit deeper if planting into very dry soils, but said he rarely encounters this condition in the no-till, heavy clay soils he uses for his research. As well, he stressed that “whether you have stones or not, it is always recommended to roll fields after seeding as this will make harvesting the lowest pods much easier and more efficient.”

Timing isn’t everything, but it helps

Because soybeans require a long growing season and are typically the last of the crops harvested in Western Canada, growers might be tempted to seed early. According to Holzapfel, it’s one temptation they’d be wise to resist.

“At best, seeding early is not advantageous, and at worst, it’s detrimental. We are doing some seeding date work and, while we appear to be doing okay seeding in the first or second week of May, there is no maturity or yield advantage compared to postponing seeding to the third or fourth week of May.”

In fact, in 2015, the foundation had soybeans seeded on May 7 and May 19, and both dates emerged and matured within about a day of each other. When seeding is pushed into June, however, Holzapfel found that there’s often a higher risk of frost injury in the fall and subsequent yield and quality loss, although even these crops tended to catch up quite quickly to the earlier seeded treatments later in the season.

“Industry typically recommends seeding into soil that is at least 10 o C. Since soil temperatures go up and down dramatically with the weather, my own somewhat crude recommendation has been to wait until at least the middle of May and then go in when the forecast looks nice and warm for a couple of days.”

It’s a lot to consider, but nobody said farming was easy. If it was, those weekend gardeners would be challenging the soybean growers for a piece of the profits. Given our desire to make everything we do faster, simpler, and more user-friendly, it’s one concern that farmers can cross off their list.