Yield Maps ROI with Fertilizer Application

By: Blake Groeneweg, CFE Precision Ag Lead

Yield monitors are in about every combine out there today, but I still get questions on what should I do with this map?

Quite frankly the first thing to do with a yield map is simple. Turn it into a variable rate fertilizer map. Apply more crop removal to areas that hit 270 bushels and less to the areas that don’t. For example, I have a corn-on-corn field that is grid sampled and a fertilizer build has been applied. The field with the use of conventional grid sample methods, it has good fertility across the field. The extra fertilizer in the low testing areas (good areas) increased production and pushed yields in the 275-bushel range. The maintenance crop removal fertilizer for the next 4 years is selected at 200 bushels an acre. Over those 4 years the good areas of the field have been shorted by 75 bushels a year. Take that times 4 years and that is 300 bushels of crop removal! Now you must make up those 300 bushels of crop removal the next time it is sampled. Below is a visual of what this looks likes. The top is 1 pass of yield data - the bottom is graphed out with yield being blue and corresponding phosphorus yield removal in red compared to straight rate fertilizer in green.                




While the field still had an average yield of 200 bushels of corn, there is great discrepancy into where the yield came from. To put hard numbers to this the high yielding area is shorted by 24 units of phosphorus and those 24 units will get made up that next time grid sampling comes around and calls for 100 units of phosphorus in that good yielding area.

Feeding the high production areas is critical in keeping your soil test levels in the economic optimum yield range. (Shown below) You don’t want areas of your field to slip into the less then optimum fertilizer area. In that area you are losing yield from lack of fertility.
 


Use your yield monitor to drive the placement of fertilizer is the best ROI on farm. It improves current yield production by feeding the right places, best return on investment of fertilizer, and cash flow by not playing catch up in the grid sampled year.

A couple of different strategies used for fertilizer application:

1. With rented ground scenarios we can blend the N P K all together and variable rate the blend of fertilizer. 1 pass and 1 application fee to keep cost low.
2. Applying fertilizer in separate components and separate bins. Fertility build plus yield map for removals. Usually results in 2 passes 1 in the fall and 1 in the spring. We have different options to fit your needs.

New technology in the cab of the combine has really increase the speed at which yield data can be accessed with the use of Climate FieldView, MyJohnDeere, and other such systems. We can stream yield data right to our Innovate program and create a fertility program from your yield maps.

Ask your CFE Agronomist on how to get connected and make the best use of fertilizer on your farm.