Your right Don, 11% would be about the best you could do @ 15 deg. We top dress here between June and August, I'm guessing the average temperature of our water is 12 deg by then , so my main mix is approximately 2t of SOA fines plus 1.2t prilled Urea. The SOA is a lot easier to dissolve, we like to use it early on our sandier soils. Later on after flag leaf , we switch to a urea only brew. In wheat the urea would be mixed with copper and a fungicide, hopefully to keep the protein up.
At 11% can you spray that straight onto the crop, or do you still have to mix/dilute it with more water when you add to the sprayer?