Yield data from 2012 crops should be utilized to make prudent nutrient decisions for 2013. Where bushel production is disappointing due to drought, reining in planned phosphorus and potassium fertilizer applications may be appropriate. If previous soil analysis has shown sufficient levels of nutrients, redirecting dollars allocated for crop fertility should be a wise decision. Applying more nutrients than needed by the crop is not only economically unsound, such soil supplementation may contribute to environmental challenges.
Sampling soil to determine nutrient levels should take place at least once every three years. Fall is generally the best time to take soil samples. Usually, periods can be found when the ground is not muddy, so that decent soil cores can be taken. After analysis, enough days before the fields are frozen can be found for application of recommended crop nutrients.
From the economic perspective, a farmer should invest in regular determination of soil fertility. Check your records. If in any field, you spent more than $200 dollars per acre on fertilizer on a crop that might gross over $1000 per acre, do the math for your situation. Even at a cost of $15 per sample (fairly comprehensive) for a 10 acre area, the cost to sample once every three years is only 50 cents per acre.
If through proper soil analysis you can save 10 percent on your fertilizer bill, or gross an additional 10 percent income on each acre, investing the time and dollars to find out what is in your soil is well worth it.
Many farmers use their fertilizer dealers to provide soil sampling and fertility recommendations. Obviously, if the farmer/dealer relationship has been profitable, one might question any need to consider alternatives. In my consulting experiences, I have seen pros and cons to farmers relying totally on commercial fertilizer recommendations. The best dealers work closely with their farmer clientele to maximize farm profitability. Those commercial interests may not sell the most fertilizer, but emphasize service and product quality instead. Dealers sometimes do not charge for soil tests, but consider the process as part of their customer service.
Many other farmers utilize independent crop consultants, who only market their expertise. Without an incentive to sell crop nutrients, they focus solely on determining crop needs. However, since billing is only based on soil analysis and follow-up fertility recommendations, their services may appear to be more expensive than that billed by a fertilizer dealer.
Nearly all dealers and independent consultants are, or have direct access to Certified Crop Advisers (CCAs). Soil fertility advice from CCAs should always make sense from both economical and environmental perspectives.
Unfortunately, some where along the line, higher than necessary crop nutrients have been applied over the years to some farm fields. I have seen a number of soil fertility recommendations that advised farmers to apply nutrients even though soil tests have shown high levels of the same nutrients in fields that were sampled.
Now to the sampling itself. Whoever pulls the soil cores should select sampling areas within a field, ideally a uniform soil area of 10 acres or less. Each sampling area should be based on soil type, slope and eroded status. In general, soils of distinctly different colors should not be mixed. For example, darker soils are typically higher in organic matter content. Areas might also be based on field history. Acreage near livestock production facilities may benefit from more intensive sampling.
At least 15 to 20 separate cores, taken at a consistent depth (6-8 inches or plow depth), should be gathered in a zigzag pattern from the sampling area. Twenty to 30 cores are even better if the area is variable and the location of fertilizer bands cannot be determined. Scrape away surface crop residue before coring.
Soil cores should be collected in a clean bucket to be air dried, crumbled and sub sampled for delivery to the testing laboratory. Don’t guess; soil test!
The views and opinions expressed in this column are those of the author and not necessarily those of Farm World. Readers with questions or comments for Roger Bender may write to him in care of this publication.