Agronomy Geeks, Western Canadian Edition — Ep. 4: How do we lose N? Let me count the ways

Ever had a soil test come back with some surprising nitrogen levels? While it’s typically lower than expected (don’t we all wish N didn’t just disappear?), every now and then a crop may have left some behind due to any number of factors, like water availability, timing of mineralization or some other something that maybe you can’t quite explain.

Nitrogen is well understood in many ways — like what levels crops need to create yield, biomass and protein. We also know how it cycles and what threatens to morph it into other forms that can be lost from the soil profile. But those losses are the thorn in the side of any farmer or agronomist crafting fertility blends for the next growing season. N can be “lost” more than a few ways, by gassing off, by leaching down out of the root zone, or by being tied up and made unavailable to the plant. (It’s not really lost, of course, it’s just not where plants can access it anymore). The rate and amount lost is always the mystery, one solved in part by soil testing, but things like expected mineralization in a year are impacted by too many variables to be easily estimated.

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Nitrogen, its behaviour in the soil, the risks of losses and how to manage those risks is the topic of this Agronomy Geeks podcast. We leave the discussion of stabilized and treated N products for another day and instead focus on how time of year impacts N loss risks and what do to if you fear you’ve lost a significant amount of fall-applied N. My guest is John Heard, crop nutrition specialist with Manitoba Agriculture, Food and Rural Development, and in this podcast we discuss the ways N is added and subtracted from the soil profile, plus how tillage and the advent of new crops, like corn and soy, are impacting N cycles in the rotation. All that and more in the episode below.

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