Fall Fertility

October 21, 2013, Submitted by Robert Corzatt of Harvest-Max Partners  - Photo courtesy of Tony Miller

2013 harvest is well under way and in some areas close to finished.  Hopefully most folks are thinking about feeding 2014’s crops. You begin setting up the planter for next year with the combine this fall. Your cropping plan should involve a good fertility program to go along with whatever tillage program you are using in your operation.

The start of any good fertility program is a very good soil test. We prefer a good grid soil sample but any type of soil sample is better than NO soil sample. We recommend soil sampling every three years to monitor what is going on inside a field boundary. Please make sure to get a high quality soil test that includes all the information needed including buffer Ph. and base saturation information of potassium, magnesium, calcium as well as hydrogen. After reviewing soil tests, the first place to start if needed is to make sure soil Ph. is at an acceptable level.  Soil Ph. needs to be in the 6.5 to 6.8 range. If soil Ph. is below the acceptable range just mentioned, no one is doing your operation any favors by spreading large amounts of P, K or other nutrients “IF” Ph.’s are not at an acceptable level. Soil Ph. levels as well as soil calcium levels are like the “foundation” of your house.  Without a good foundation, the house does not stand well.

There is lots of debate over what acceptable levels of soil phosphorous and potassium need to be or should be. No university or expert seems to have a single answer. As we move forward with higher yields of all crops these need to be continued to be challenged. In my opinion, for profitable crop production a minimum goal should be at least 25ppm of P1 phosphorous and 200ppm on soils with a cation exchange capacity (CEC) of 10 or more. On soils with a CEC of less than 10 you quite possibly need to look at other means of supplying fertility at key times of the year to the growing crop. On soils with CEC’s less than 10 one would also have to question fall fertilizer applications also with the possibility of leaching with heavy rainfall. Remember what we put on this fall/winter needs to be there next summer to feed the crop at key times.

On the Nitrogen side of things - please remember that we should not be applying N when it’s too warm. I am amazed every year when I see NH3 rigs running with 65 degree soil temps. With the cost of N in the last few years being a very large portion of corn crop, I would do everything I could to protect that investment.  We also have to remember that N investment we are making today has to be there and available to the crop next June, July and August when the corn crop is really needing it. So if we apply it when the soil temps are too warm and the soil bacteria convert it to a leachable form, we stand to lose a large portion of that investment and not maximize our ROI by limiting yields. Two things I would also suggest if you are applying fall N.

  1. I would suggest using N Serve to slow down the conversion and protect my N investment. 
  2. I would suggest only applying a portion of your N needs this fall as NH3 and saving the remaining N application for spring/summer as a weed & feed and/or side dress application. Making sure we have N available at the key times your corn crop needs it as to not limit yields.

To summarize things: Fall is a great time to get fertility out of the way and tillage done. Please remember that we are all making large investments that we are wanting/expecting a high ROI on come next fall. For that to happen, we need to do some good planning right now. Make sure you have a good soil test to work that is recent in the last three years. If not, take the time to have one taken. Without a good soil test it’s like shooting ducks in the dark. You can’t hit what you can’t see so you stand to miss your yield targets without one.

In lots of areas of the country, we have good crops for the growing season coming out. Those crops removed nutrients that will need to be replenished for profitable yields next year. Take the time now to do your homework and spend the money needed, where needed to raise a great crop next year.

Have a safe harvest and fall season!