Working with a rapidly-depleted soil moisture bank account

Soil moisture reserves from a wet year in 2016 carried the 2017 crop through a very dry summer across the southern Canadian prairies, enabling some better-than-expected yields, but also leaving the moisture bank account depleted heading into the 2018 growing season.

The rapid transition from wet to dry has several implications for the upcoming season, as highlighted by Brunel Sabourin of Antara Agronomy at the 33rd St. Jean Farm Days in southern Manitoba last week.

“It’s made for an interesting situation going into next year where we have depleted soil reserves again, and haven’t had much snow yet,” he says in the conversation below. “Because we had a lot of water moving through the plants out of the soil, on soil tests we’re seeing a lot higher salinity levels and carbonate levels, which is a pre-factor for iron deficiency chlorosis (IDC) in soybeans.”

In addition to the potential for similar issues as last year when there was unprecedented yellowing attributed to IDC in soybeans, Sabourin notes herbicide residue carry-over should also be on the radar due to the lack of rainfall to break down chemistries that were applied last year.

As for nutrient considerations, soil tests are showing slightly lower phosphate levels, which could be due to lower microbial activity in the top two inches of soil, he says, noting the powder-dry top layer may have also been mixed with lower core depths in the soil sampling process, altering test results.

Given the large yields in some areas last year, it’s no surprise nitrogen availability is also reduced heading into 2018, says Sabourin.

“We might have sucked a little more nitrogen out of the lower profile than we typically would have, but it’s going to be an interesting year this year to see what we get for weather. We’re going to need those timely rains to carry us through the season.”

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