At Mid-County, we have been grid soil sampling, spreading dry fertilizer, and spreading lime using Variable Rate Technology (VRT) since 1999. Over the years we integrated VRT anhydrous ammonia and VRT herbicide application capabilities into our agronomy program to meet our customers’ needs. Corn, soybeans, and fertilizer prices were about half of what they are today, but the increased revenues from higher yields or savings from using less fertilizer paid for the grid sampling and additional cost of equipment to apply the fertilizer correctly.
With today’s high prices for corn, soybeans, and high input cost; grid sampling is even a better deal today since the cost of sampling has remained relatively the same. To do a 2.5 grid for P, K, pH, and organic matter it cost roughly $8/acre for the sampling. An additional $3/acre charge for the two VRT spreader applications along with the sampling gives the total cost of $11/acre of additional cost over a conventional fertility plan. Samples are normally used for four years, so the $11 spread out over that time is only $2.75/year. That is less than a bushel of corn and less than a third of a bushel of soybeans at today’s prices.
The best fields to be grid sampled are the poorest producers or newly rented ground. There is a tendency for producers to grid sample the “Home” field or their most productive ground. These productive fields usually have high levels of fertility to start with, so any money saved is from reduced fertilizer usage and not increased yields. Poor producing fields will have a tendency to show inadequate fertility in large areas that a composite sample will simply blend in with the rest of field.
Another example where grid sampling really pays back well is for spreading lime. If a composite sample shows a pH of 6.5 or less; there is high probability that part of that field may have pH below 6.0 and may require lime in order to attain top yields. If you are planning on applying a flat rate of lime, grid sampling will pin point exactly where it is needed.
Soil sampling is an integral part of a total farm management system. Grid sampling may have a fit on your farm and with today’s high prices it is becomes a comparative bargain. At Mid-County we have the experience in precision farming and a long track record with VRT fertilizer spreading to get the job done right.