Farm Progress

Jenkins Precision Ag Service has provided fertility services, including soil sampling, tissue analysis, and fertilizer recommendations, for 30 years.

Patrick R. Shepard, Contributing Writer

March 16, 2017

6 Min Read
Joe Jenkins, from left, wife Dianne, and agronomist Matthew White service corn, soybeans, cotton, rice and grain sorghum in northwest Arkansas, Missouri Bootheel, west Kentucky and west Tennessee.Patrick Shepard

Mid-South growers have remained good stewards of the soil, making the land better as they farm it.

And they have done so amid a deluge of changes over the last 30 years, including major crop shifts, planting of cover crops, and implementing minimum-till and no-till practices.

Commodity prices engineered the dramatic acreage shift from predominantly cotton to grains in the Mid-South. However, says long-time soil fertility consultant Joe Jenkins, as the region’s growers shifted more acreage from cotton to grains, they did a good job of adjusting their fertility programs to fit the needs of grains.

“Corn, soybeans and other grains have different fertility needs than cotton, which requires a little more potash than grains,” he says. “Cotton doesn’t have a big, fibrous root system; it can’t uptake nutrients as well as corn and soybeans.

“So when I work with cotton, I recommend higher potassium levels. The amount of potash that we apply when we rotate to cotton kind of cushions subsequent grain crops that might not need as much of the nutrient.”


Jenkins Precision Ag Service has provided fertility services, including soil sampling, tissue analysis, and fertilizer recommendations, for 30 years.

Jenkins and his wife, Dianne, and Agronomist Matthew White, service corn, soybeans, cotton, rice, and grain sorghum in northwest Arkansas, the Missouri Bootheel, west Kentucky, and west Tennessee.

Related:2017 High Cotton winners adapt their operations to achieve success

Jenkins is pleased with the increased usage of cover crops in the Mid-South, saying they can help improve the soil and eventually increase yields. “We run a test, at a grower’s request, that shows where a field rates in the percentage of what is considered soil health,” he says.

“Cover crops can improve soil health. In as few as three years, we’ve seen an aggressive incline in soil health with the use of cover crops.”

Jenkins works with one Missouri grower who has been integrating cover crops into his farming operation for six years. “He now says he can’t imagine planting a row crop without complementing it with a cover crop.

“He uses cereal rye and radishes as his basic cover crop and says they help dry his ground so he can plant his row crops earlier than he could before. They also make his ground more tillable.


“If I were going to plant a crop like cotton or corn that demands a lot of nitrogen, I would recommend planting a cover crop that would give me nitrogen — something like a legume.

“For example, on one field we planted crimson clover, and later planted corn when the clover was about a foot and a half tall. We planted right into the green cover and then applied a burndown, then later applied 100 units of nitrogen per acre on that field.

“You have to match the cover crop to the row crop you intend to plant — and to what your goal is, whether it’s adding nitrogen and/or supplementing weed control. A good cover crop can save on weed control and nitrogen.

“A thick cover crop helps deter weed emergence; in some instances, it makes a huge difference. One grower/ginner in Mississippi uses a lot of cereal rye in his cotton and has cut his weed control costs considerably.”

Jenkins expects the Mid-South might plant a little more cotton in 2017, and says cover crops work well in the crop. “In addition to using cereal rye for weed control, I also like radishes because their big root system improves soil tilth. There’s some concern that radishes produce an enzyme that can potentially hamper cotton seed germination if they are not terminated early, but you won’t have a problem if you make a good kill of the cover crop two weeks to three weeks prior to planting cotton.”


Over several decades, Mid-South producers have gradually shifted from constantly cultivating fields to minimizing steel in the field, Jenkins says, and land stewardship has changed since growers parked the breaking plow in the barn and transitioned to minimum tillage and no-till practices.

“Any time you till soil, you decrease the organic matter,” he says. “However, some modern tillage equipment leaves 80 percent to 90 percent of crop residues on the soil surface. After three to four years, growers using minimum-till and no-till should see an increase in organic matter. It’s another way growers improve the soil while saving time, diesel, and money.”

Fertility is more than applying NPK, Jenkins says — it’s also paying attention to lime and micronutrients, including boron and zinc. And it’s also about adhering to the Four Rs of Fertility Management: the right source at the right rate at the right time in the right place.

“All of this begins with a solid soil sample,” he says. “We do zone sampling, which is economical for growers and gives us the detailed information we need. We send the samples to Brookside Laboratories in New Bremen, Ohio, where the analytic work is performed.”

Jenkins reads every soil report from every soil test that he takes before making fertility recommendations. “You absolutely have to do that to make the correct recommendations,” he says. “For instance, the report might call for lime, but you have to determine the type of lime product that you need to use. The only way to know what you need is by reviewing the soil report, rather than letting a computer generate the recommendation; a computer program doesn’t know which product to use.

“For example, if you have 52 percent to 55 percent calcium and 5 percent magnesium, then you will need dolomite lime because it’s a magnesium-based lime. Likewise, if you have 55 percent calcium and 12 percent magnesium, then you will need high calcium lime.”


Variable rate application is a great fertility tool for growers, Jenkins says. He reviews soil reports and then decides whether it’s economical to do a variable rate or a straight blend over a field.

In most cases, to cover the field one time with variable rate, he tries to use a base blend that will work for the whole farm and varies the most limiting product. He varies the rate based on the nutrients in the zone.

In the three decades Jenkins has been working with soil fertility, he has seen yields increase, partly due to increased fertility, but also due to better varieties and hybrid genetics.

“You have to match the better genetics with increased fertility to realize the optimum genetic yield potential of the newer varieties and hybrids,” he says. “Also, higher yields draw more nutrients from the soil. If you don’t increase your fertility along with the yield increase, your soil fertility will eventually decline. You have to stay up with the yield curve.”

Jenkins Precision Ag Service is an independent precision soil management firm based in Kenton, Tenn. The business is composed of certified crop advisers. “We are a third-party, unbiased entity, that only has services, not products, to sell,” says Jenkins. Services include balanced soil fertility management, nitrogen monitoring, comprehensive GPS mapping for accurate sampling for fertilizer application, data management, complete analytical services, and manure management.

Info: or 731.446.5812.

About the Author(s)

Patrick R. Shepard

Contributing Writer, Contributing Writer

Subscribe to receive top agriculture news
Be informed daily with these free e-newsletters

You May Also Like