Producers who had lots of rain this summer will want to pay attention to their soil’s chloride levels when planting cereals next year, advises Brandon Green, an agronomist with Enviro-Test Labs in Calgary.
He said while nitrogen, phosphorus, sulphur, potassium and micronutrients receive a great deal of attention, producers don’t hear or read much about chloride. That’s because prairie soil often has a fair amount of chloride. Producers who apply potash for the potassium pop-up effect also apply chloride, because potash is 46 to 48 percent chloride.
However, all the rain this summer could change conditions for next year.
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“Chloride is an essential nutrient for plant growth and cereals are the more susceptible of prairie crops to Cl (chloride) deficiency”, said Adrian Johnston with the Potash and Phosphate Institute.
“Of the cereals, oats is the least susceptible while winter wheat is the most susceptible to chloride deficiency, with spring wheats and barley in the mid range.”
Chloride, like nitrogen, is a mobile nutrient in soil. As water moves down into the soil, it carries the chloride with it. In dry spells, when soil moisture moves from the subsoil to the surface with evapotranspiration, chloride will move upward in the water.
With the high rainfall in many areas of the Prairies this summer, chloride leaching has likely occurred and soil testing is the only way to be sure of adequate levels. Much of the Prairies also received plenty of rain last summer and a high percentage of the soil samples sent to Enviro-Test Laboratories last fall and spring showed low levels of chloride for cereals.
Chloride analysis of a soil sample is $5 per sample, in addition to other analysis, but producers may want to sample deeper than they normally do. Green said chloride can be inadequate in the top six or 12 inches but more than adequate deeper in the soil, so ideally producers should sample to the 24-inch depth.
“We can analyze the Cl on a zero to 12 inch sample and even on a zero to six inch sample, but as with nitrogen, you’re not looking at the whole picture unless you sample to 24 inches,” Green said.
To mitigate the “pain” of taking two samples, Green and the other agronomists at Enviro-Test promote the use of a zero to six inch plus a zero to 24 inch sample combination. They suggest using a truck-mount sampler to take the zero to 24 inch sample and then use a hand probe to take a zero to six inch sample.
Green said farmers in wet areas should ensure they soil test for chloride on fields where they plan to plant cereals next spring. It might save time and money.
Lee Moats, a farmer at Riceton, Sask., has been fertilizing cereals with potash for a number of years.
“Some of the winter wheat varieties, CDC Kestral was the first post-Norstar variety that I grew, have a condition called physiological leaf spotting,” he said.
“It looks like it’s diseased, but it isn’t. If you were looking at them you’d say, ‘geez, it’s got septoria on it. It looks like it’s got disease lesions.’ We put on potassium chloride – potash fertilizer – and it eliminated the physiological leaf spotting.”
Moats believes potash fertilizer also reduces lodging.
“Right now if you drove out in my field, you could tell where the potassium chloride was because it’s not lodged as bad. I’ve got 1,000 acres of lodged crop here, so not lodging is looking pretty good,” he said.
“But the biggest issue with winter wheat has been this physiological leaf spotting. The plant looks so much better, the logic says it can’t help but be better, because it’s got leaves that are green instead of looking ugly.”
With the perceived benefits, Moat said he uses potassium fertilizer on winter wheat and barley. He’s convinced he ends up with healthier plants.
“Our method is to get the chloride put in with the fertilizer we apply at seeding time. It’s there, it’s on and it’s the most convenient. Broadcasting some low rate of potash is not very cost efficient. Mixing it with the phosphate you apply at seeding time is the preferred method. I’m doing that again this year.”
With winter wheat, Moats single shoots so the potassium chloride is blended with his phosphate fertilizer and applied with the seed. With barley, it goes in as a band, with a double-shoot opener.
This fall, he’s applying 25 pounds of P205 and 30 lb. of potassium with his winter wheat.
Moats said it’s a controversial decision because there hasn’t been a lot of scientific documentation confirming a response to potassium.
He said studies by prairie researchers haven’t received a response with any consistency, but he’s willing to make that decision based on his own experiences.
