4R Nutrient Stewardship

The Fertilizer Industry in the US and Canada has recently developed the 4R Nutrient Stewardship concept.  More information can be found on the Fertilizer Institute Web page.  Ford West made his case for the concept at the CCA meeting last week.  Someone asked him if he thought we were not already following that concept in making our recommendations.  He responded in a positive way. 

I think the concept was developed for two reasons.  To emphasize to the public that we know what we are doing, and to stress to consultants and fertilizer dealers the need to be mindful of environmental stewardship in making our recommendations.  The whole idea begins with having good scientific data to make good decisions.  Reliable Soil Sampling techniques, Reliable laboratory data, and reliable interpretations of the data are needed.  Right now, in Illinois, the Illinois Agronomy Handbook says that once in 4 years is often enough to sample.  Since sampling "error" is the most likely source of error in  soil testing, is that often enough?  We prefer yearly sampling to allow us to tweek fertilizer amounts applied every year.  We also get a much better picture of trends.  You could make a case for every other year in a corn soybean rotation where fertilizer is applied on corn only.  Less often than that does not follow the $R concept in my mind.

The idea of fertilizing according to what the crop removes is easily carried too far if not backed by data.  Environmental factors such as microbial activity play a big role  in nutrient availability and soil test levels.  We need yearly data to capture what is going on with those variations.  I have seen soil test levels go up with no fertilizer applied and I have seen levels go down with no crop grown.  Soil Balance is an old concept, but still a good one.  If one test level is too low, it does not matter what the other levels are.  In the long run, an effort to bring all levels to an ideal   makes management easier for the producer and the consultant.  Properly implemented variable rate application can help us manage our soil and balance fertility levels. 

Nitrogen management is a whole blog in itself if we are to follow the 4R concept.