“We need to start thinking of fertilizer as a scarce commodity that needs to be conserved and protected,” says Jeff Schoenau. The research scientist and professor at the University of Saskatchewan gave a talk called “Strategies for maximizing returns on fertilizer inputs” at the Crop Production Show in Saskatoon in January.
Here is my summary of his strategies:
1. Put nitrogen, especially urea and anhydrous ammonia forms, in the ground in a band. This reduces losses. The best you can hope for is to recover 70 per cent of your nitrogen fertilizer in a given year. In many cases, that actual recovery is 50 per cent or lower, Schoenau says. Watch out for damage if the rate is too high or too close to the seed. With inhibitors and slow-release nitrogen products, you can reduce nitrogen losses and you can reduce seedling injury from seed-placed nitrogen.
2. Where you place nitrogen in the soil is not as important as where you place phosphorus. Nitrogen moves easily in the soil, so it can be a few inches away from the seed row. You need to place phosphorus in the seed row because it won’t move closer to the seed. Recovery of phosphorus fertilizer is 30 per cent, at best, in any one year. But that unrecovered P stays in the soil, increasing reserves for another year.
3. Schoenau is a fan of putting all your seed and fertilizer down in one pass. “That is a pretty darn efficient system.”
4. Picking a rate is probably the most challenging aspect of nutrient management, Schoenau says. He recommends soil tests, especially on new land you’re renting or if you’ve been using the same fertilizer blend and rate for all crops and all fields. With soil test analysis, labs also provide fertilizer recommendations. Those recommendations all hinge on you taking samples that provide a good representation of the field. “Bad sampling is the biggest source of error in fertilizer recommendations,” he says.
5. More on rates: “Keep increasing your fertilizer rate until the last dollar spent on fertilizer gives you a $1.50 return in terms of higher crop yield,” Schoenau says. “With high crop input costs, farmers have a tendency to say, “I’m not going to put any fertilizer on.” But if you do that, you’ve already hooped yourself,” he says. The first few pounds of fertilizer provide a six to one or even an eight to one return on investment. It’s better to scale back and provide balanced fertility than to starting chopping inputs entirely.
6. Use every opportunity to recycle, retain and reclaim nutrients on your farm. If you have old hay bales or out-of-condition grain, it can be an alternative source of nutrients. Grain has about three per cent nitrogen, Schoenau says.
7. He likes feeding cattle out on the fields. Uneaten straw and hay become nutrient sources. So does the manure.
8. Control your weeds early. Wild oats, for example, can take up a lot of nutrients and over half of their nutrient uptake occurs in the first four weeks after emergence. Those nutrients will be returned to the soil eventually, but they will not be available to the current crop.
Jay Whetter is editor of Grainews