Did you know that I do a lot of math over the winter? Actually, we do a lot of math on the farm, period (sometimes in the form of…if I can get 15 acres/hour done, and have 45 more acres to do, what time will I be home?).
After harvest we immediately start planning for the next crop. One very important part of the next crop is the fertilizer. The main sources of fertilizer we look at are nitrogen (N), phosphorus (P), and potassium (P). On our farm we have different sources of fertilizer that are applied onto our field as:
- Cattle manure
- Hog manure
- “Commercial” fertilizer (what we have to buy to put it on our fields)
This may seem simple. “Put on fertilizer!” Just like everything, it ISN’T that simple.
We have multiple fields, with multiple yields and crops. Which then means each field has a different removal of nutrients (for each bushel of corn/soybeans they remove N-P-K).
So we have to look at:
- What crop was on each field
- What was the yield (which then relates to what was removed as nutrients from the soil)
This will tell us how many nutrients were removed for this past year (we use ISU values to determine what was removed)
We also need to know:
- What is the soil analysis for that field?
- Did we have high analyses for P and K? or low?
- What was applied as fertilizer the year before? or, the history of the field?
- What do we want? are we short (too low) on nutrients, long (too many)? what is the investment?
- What will the weather be? What’s the plan for next year? 2 years? 1 year? etc
Remember, each of these answers is different for each field!
In summary, Mr. Snyder & Mr. A would be proud that I’m putting my math skills to work. And, Excel ® is a great program to help me out!