Kinsey Agricultural Services

Once the soil is properly corrected in terms of the needed fertility levels, is there any good reason to keep testing the soil every year?

Due to the nature of our business it would be to our benefit when someone decides to have us do another set of soil samples and recommendations for them! So for some it may be easy to assume that any further answer given to such a question would simply be geared toward that end! But keeping in mind that our job is to be that of an advisor, and the client is the manager, perhaps some of the information presented here will help in that regard.

The Soil Nutrient Needs to be Maintained

It seems that far too many people get the idea that when a soil is correctly balanced with all the needed nutrients, it will then be many years before it needs more than a routine maintenance in terms of fertility levels. This is not the case for any productive soil, especially when you want to achieve top quality and excellent yields.

As nutrient uptake and yields improve, more of all the elements required for growth of that crop will be taken up. If these losses are not measured and replaced, production capabilities will decrease even more quickly than would previously have been the case because more is needed and removed as yields and quality increase.

Many involved with soil fertility suggest taking a soil sample every three or four years. If all that is being sought is a very generalized direction then this time frame is at least better than none at all. But in order to achieve the utmost from a soil, it should be analyzed and amended where required prior to every major crop to be grown there. This is true even if your last soil test on the field showed fertility levels to be excellent.

A Result of Neglecting to Soil Test

One client who grew cotton was amazed that we could tell him, from the soil samples, a particular out-of-the-way field was one of the best he had. The next year he decided to retire and wanted to wait until the farmer signed a lease before taking soil samples again. Though intentions were good, four years of crops were grown on this land before it was re-tested. This same field that tested as one of the best five years earlier now tested to be one of the worst.

Again the owner was amazed that we could correctly tell him this based purely on the soil samples taken. The field went from one of his best to one of his worst in five years! This is not an isolated case. The soil which produces the most loses the most, especially if what is harvested is taken elsewhere.

A cattleman who grew his own pasture and hay expressed it well when he pointed out that just making the equivalent of one extra bale of hay per acre would more than pay for the cost of soil testing. And another farmer once confided that if he applied just one nutrient that he did not need in order to make a crop, the cost to him is far greater than that of a soil test. Perhaps even more important is the loss in yield by failing to identify a nutrient deficiency that has hurt the crop that would have shown up if the soil had been tested.

Leaching of Nutrients

All of agriculture recognizes the need for moisture in some form, generally rain or irrigation water, in order to make a good crop. But it is also recognized that these same sources of moisture can deplete the soil of both needed and unneeded elements.

For example, when used correctly, gypsum (calcium sulfate) or other forms of sulfur materials, can help leach out excess salts, particularly sodium. However, after the problem is corrected if you continue to use sulfur or sulfates to excess it will result in removing additional nutrients that should be conserved for growing the next crop.

Also, too few consider that an excess of nitrogen, once it has converted to nitrate nitrogen and can be leached downward through the soil, can also result in forming nitric acid, which will deplete calcium from the soil as it moves with the groundwater. In addition, high bicarbonates in well water may cause calcium to be stripped from the soil thus lowering the pH and reducing the uptake of nutrients required for optimum fertilizer utilization, whether supplied from commercial fertilizers or composts and manures.

An Annual Soil Test Aids Good Nutrient Balance

A good soil test every year helps identify these conditions and avoids their possibly damaging effects. It is a mistake not to take soil samples properly and use them for the benefit of the soils and the crops to be grown there.