Ed, there are two things that need to be considered when asking whether grid sampling/vrt pays or not. First, does it reduce the amount of fertilizer being applied? And second, does it increase yields?

As to the first consideration, I can tell you unequivocally that in the vast majority of cases, the amount of fertilizer being applied is less with grid/vrt. So why is this? It's because we have systematically over-applied fertilizer in the past. In 2002 (my first year here), I did an analysis of a random cross-section of all the soil samples I submitted during the fall of that year in order to get an idea of where our fertility levels reside within my trade area. This is what I found:

                                        The chart above represents the average of 1600 samples - about 25% of annual volume.

Needless to say, it became quite apparent that we were overusing phosphate (and yes, this is coming from a "fertilizer dealer" that Mr. Moyer says is only interested in selling tons). It also became apparent that a grid/vrt program would offer our customers some significant savings - and it has, our phosphate sales have steadily decreased as our vrt acres have increased. In most cases, our customers have easily recouped the extra costs of sampling and application.

The other aspect of the grid/vrt equation is increased yield. In theory, variable rate application should increase yields. I am convinced that it does, but it's extremely hard to quantify the results. You simply cannot compare a vrt field to a non-vrt field. It's also very tricky doing split field comparisons because both halves of a field never yield the same. A person also needs to consider that any fertility program is based upon a certain number of years for buildup - usually 4 years - so a single year comparison is not really valid. It takes time to realize the full benefit of the program, so when a person tells me that yeah they tried it once and it didn't pay, I take it with a grain of salt.

With that said, we really shouldn't have to justify grid sampling/vrt based upon yield. It should come down to a cost savings on inputs. In the case of lime, there is almost always a savings over broadcast. With P2O5, a large percentage of the time you'll see a savings - especially if a person has over-applied in the past. K2O is a different story. I would guestimate that approximately 50% of the time a person will see a savings, so realistically, I could not justify vrt on that alone.

The overriding theme here is that grid/vrt can and does save money and with the high cost of fertilizer, that savings is much larger today than in the past. Couple that with the ability to replace the actual nutrient removed by the crop rather than trying to predict what the crop will remove in the future, a person soon realizes that the savings can be considerable. This is not always the case, but it is in a high percentage of the time. I'm not a gambler, so I stick with the percentages.