[EDITOR’S NOTE – This month’s column comes from Jason Edenfield from the University of Georgia Extension. We welcome your questions about financial and farm matters, business or personal – just send them to and look for the answers or request a private reply.]

Whether you are growing cotton or onions, soil testing is one of the most important aspects in crop production. Unfortunately, many producers overlook the importance of this simple, but major production practice.

Here are just a few things for a producer to consider when taking soil samples for their upcoming crop.

Jason Edenfield

First is timing. Often times, I have producers bringing soil samples into my office just a couple of weeks before they plan on planting the crop. Honestly, this does not give a producer enough time to make what is quite often, an important change in the soil’s pH or nutrient levels.

We must remember that we can’t change the nutrient levels of the soil overnight. It’s a process. When we add lime to the soil to bring the pH up to an ideal level it takes time, months actually.

The same holds true for fertilizers as well, maybe not quite as long as it does for liming the soil, but the process still takes time, especially in nutrient deficient soils. When you take soil samples, give yourself enough lead time to get the full benefit of the fertility recommendations given.

Second is how we sample. Traditionally producers went out to the field and randomly collected samples throughout the field to get an “average” soil sample. Recommendations for lime and fertilizer would be based off of this “average” field sample. This way of collecting soil samples would lead to positive yields, if the high and low yielding areas are close to the “average”.

Is this method “bad”? Not necessarily. However, if soil sampling tells us anything, it’s that even in our smallest fields we can have some high levels of variability. As a result, we may leave some parts of our fields with way too much or way too little fertilizer and lime.

With the variable rate technology we have available to many producers today, we should consider separating a field into smaller areas and manage them differently.

We can then sample these smaller areas and determine if the soil properties are contributing to differences in yield. If the field does show differences, the producer may see where it economically beneficial to use variable application rates of lime and fertilizers.

So lastly, how often do you need to sample? If you have an adequate pH level for your crops and your soil sample results come back in the adequate or medium range it may be that you only have to test every other year.

However, if your soil samples have a low pH or come back as deficient you may need to sample yearly or even between crops. One thing to remember is it is better to sample more often than not often enough. Don’t neglect soil sampling until a fertility problem arises. Again, correcting these issues take time and don’t occur overnight.

Soil sampling is one of the most important practices we use in crop production. It’s like I have often said, a productive crop begins with a productive soil. No matter how good our weed control is, or how much we irrigate, we can’t overcome unproductive soils.

Make your soils as productive as you can by soil sampling, and as always if you have any questions about soil sampling or agriculture please contact your local County Extension Office.

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  1. My brother has a small farm that he started growing things this year and he is thinking about getting his soil tested to make sure that it is healthy. You make a great point that it is important to bring the soil in months before planting crops. This way the company will have time to add any nutrient levels that are missing from the soil and will give my brother peace of mind that his soil is healthy.

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