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Value of Data: Nitrogen Use Efficiency

by Jan 31, 2011Value of Data

Last week, we introduced our “Value of Data” series where we will discuss topics to show how data has the potential to help you increase yields and profit on your operation. One such topic is your nitrogen use efficiency. Does your car or truck have an electronic miles per gallon readout?  Have you ever compared that to the real miles and gallons used?  I have compared from time to time, especially on long car trips.  It is more or less accurate, but if I want the real efficiency of my car, I use the standard method of miles driven/gallons to re-fill tank to full to calculate it.

Similarly, while there are other factors that can affect nitrogen (N) efficiency in your fields, comparing your as-applied N with the grain harvested is a good barometer to use when planning for future growing seasons.  It can also be a good measure for years with ‘abnormal’ rainfall – the last 3 years would definitely qualify in parts of Iowa. It is important not to confuse efficiency with economics when it comes to which N rate, form, and time of application is best for your farm.  In years such as this with higher commodity prices, even though N is also higher, there is a good chance that extra N at the right time in the growing season can be beneficial to the growing crop and will produce more bushels per acre to offset the extra expense.

I’ve used SMS Advanced to calculate the N efficiency in our farming operation for the last several years.  Doing this can be as elaborate or as straight forward as you like – from including starter fertilizer credit, N contribution from soil OM, or just the standard N/Yield. The result is a map of your field that allows you to see where the field is most productive on applied N, and if done over all your fields, an average for your farm.

Nitrogen use Efficiency image

The map to the right is the result of our operation’s equation.  The majority of our N is applied as a sidedressing operation, and in our corner of Iowa, we have had pretty good growing conditions the last few years, so our N efficiency is good on average.  It has been through using test strips and comparing economics on our farm over the years that we have landed at the rates we are using now.  For our farming operation, we have used our data to optimize the economic N rates, but continue to put test strips in each year to see if the changes in crop value and cost of N are still ideal each year. The data we are collecting is proving valuable in its ability to help us make important decisions regarding our N application.