1. N reduction not a given. If you plan to use GreenSeeker or other similar technology, don’t count on always reducing N rates, especially at seeding. There are risks associated with putting less N at seeding, says Chris Holzapfel, researcher with the Indian Head Agricultural Research Foundation. There’s the risk of not putting on enough because if weather takes a turn for the worse when you need to be topping up on fertilizer, it could delay proper timing for the crop.
2. Establish the high-N comparison strip before or at seeding to achieve best comparative results with the average N strip. Don’t delay.
3. Compare the strips at the right time. The biomass reading to predict yield and the crop’s response to added N is most accurate at specific growth stages. For cereals, go in between the 5.5 leaf-stage and flag leaf. For canola, N should be applied before flowering and as early as the six-leaf stage in uniform fields.
4. Keep the growing-degree-days (GDD) number handy to establish yield potential. While GreenSeeker does most of the calculations for you, you will need to tell it how many GDDs you’ve accumulated before churning out results.
5. Calculate N cost and estimate crop price before deciding to top dress. The more expensive the fertilizer the more likely a split-application will make you money. Also, if crop prices are in the toilet, it’s important to crunch the numbers with a realistic crop price to see if more N is really worthwhile.