Nitrogen is a mobile nutrient. Its quantity in the soil is constantly changing. So the amount of nitrogen fertilizers depends on plants' current condition. The vegetation index is a suitable tool for providing an overall assessment of the crops' conditions. This is the index we rely on in OneSoil when creating a variable-rate application map. In the OneSoil web app,
you can identify zones with low, moderate, and high vegetation indices on the fertilization date, set fertilizer dose, and create a prescription map for equipment. The app is completely free. How to distribute fertilizer rates by vegetation zones.
There's no right answer. Figuring out which zone needs more nitrogen and which one needs less depends entirely on the region's soil types and climate. I enter three rates in each test vegetation zone and analyze the result to determine the best method for a particular field.
In my experience, regions with arid climate require more nitrogen to be applied to zones with a high vegetation index, whereas regions with sufficient moisture supply need to be fertilized more in zones with a moderate vegetation index.