Connor Lynch
Farmers Forum
KINBURN — When it comes to getting nutrients into the crop, nitrogen often gets all the attention.
But it’s far from the only nutrient crops need. Potassium, or potash as it’s commonly known, matters more than many farmers think, and is in shorter supply than many of them know.
Agronomist Paul Sullivan who runs Kinburn-based P.T. Sullivan Agro Inc., said that potash has become something of a forgotten nutrient. Nitrogen gets a lot of attention, especially in corn, and phosphorus has become increasingly important from an environmental perspective, as runoff has contributed to Lake Erie’s algal blooms.
Sullivan said that in 2015 and 2016, while monitoring soil levels with some of his customers, he started to notice levels dropping. “We were taking a lot more off than we were putting on,” he said. Data came out around the same time from Ontario’s soil fertility monitoring and found that potash was more important for crop performance than anyone had previously assumed.
It’s worth finding out what your potash levels are in your field and boosting them up if they’re low, said Sullivan, with a good target being 120 ppm. Not unlike tile drainage, it’s a good way to get more out of your existing operation, but you shouldn’t expect to get your money back in one year.
Sullivan worked with Carleton Place farmer Mark Foster, of Jockbrae Farms, doing some work with added potash back in 2018. In soybeans in particular, they saw some remarkable results, he said. “Where we expected to gain yield, we got 11 bushels.” A compounding factor was a dry July, he said, meaning that the extra potash was maybe more effective than it would’ve been otherwise. Other research on corn, Sullivan said, showed that potash was at least as important, if not more so, for a corn crop than soybeans, especially in a dry year. The yield response from building potash levels was similar to soybeans.
And having those nutrients available to the plant early in the year is crucial. The fall is a great time to boost potash levels, he said. “Early-development is crucial to setting the yield ceiling. If (corn) doesn’t have sufficient potash very early, from almost emergence time, we see that ceiling drops significantly.”
But a challenging year illustrates the importance of building baseline soil fertility in nutrients that may be lacking, like potash. If you’ve built your soil up, those nutrients aren’t a limiting factor in your yields and you have some fertility your crops can draw on without you having to put inputs in. In other words, invest in the soil when you can afford to, and reap the benefits when you need them.
Likening it to an engine, Sullivan said having low potash levels (or any other nutrient) is like having a car not running on all cylinders. If you’re not driving it too hard, maybe you can get by. “If you need the full horsepower, that’s when that becomes a bigger issue.”
