First, I want you to always have this at the back of your mind, “before fertilizing you should consult with an agronomist or extension professional of your area” Well, this may not be necessary if you are a peasant farmer. In order to achieve the greatest return on your fertilizer, always endeavor to take note of the following:
1.) Strive to maintain soil health:- good rotation of crops, use cover crops, minimize tillage, maintain surface residue to cool the soil and prevent the rapid breakdown and loss of organic nutrients, etc.
2.) Test your soils:- know the health of your soil by testing it. Test it over time to see what nutrients are becoming deficient and respond with best management practices to correct them.
3.) Use the proper fertilizers and time their application according to when the plant needs them. This is the single largest way to minimize how much you have to spend on purchased fertilizers. Nitrogen is the most responsive to timing because it is the most sensitive to environmental loss from leaching, volatilization, and denitrification in waterlogged soils. When Nitrogen is applied at the right time for the plant’s needs, you can use as much as 50% less than you would have to apply if you did it all at planting, for the same yield.
4.) Control placement of fertilizers when planting the crop, by applying your basic starter fertilizer in a band, or in closer proximity to the germinating seed, you will receive the same response as if you broadcast it in many cases; particularly Phosphorus and starter Nitrogen. Broadcasting Phosphorus at 4X the rate you would band it at still might not give the response that banding it near the seed will. Most annual crops that require a lot of nitrogen only need a small amount of nitrogen to get started in a healthy manner. The balance can be put on after the plant is actively growing.
I will like to acknowledge Mr. John Deibel (Freelance Writer for Tractor Export)