Challenging Soil pH Levels Remedied With P Fertilizer Efficiency Products

It's no secret that Kansas soil pH levels vary widely, according to Jeremy Olson, Kansas State University graduate research assistant, Manhattan, Kan. Olson is working with soils having an 8.2 pH level. He's found that phosphorus-enhancing products, such as AVAIL® Phosphorus Fertilizer Enhancer, enable phosphorus to be taken up by the plant, resulting in a healthier, higher-yielding crop.

Olson conducted a field study in 2009 comparing corn yields. He tested two different Nutra-Flo fertilizer mixes: 6-24-6 and 9-18-9, both with and without AVAIL. He applied 30 pounds per acre P2O5 through a subsurface-drip irrigation system (i.e., SDI) at the V7 growth stage. AVAIL was added at a 0.5 percent volume/volume basis. To make nitrogen a non-limiting nutrient factor, surface urea was applied at 160 pounds per acre. A 2X2 starter fertilizer of 17-17-0 was applied with the planter at 8.4 gallons per acre.

As indicated by the table below, Olson found that both starter and injected fertilizer paired with AVAIL affected grain yield.

"AVAIL especially increased grain yield in the 2X2 starter treatments," says Olson. "Split-applying starter fertilizer 2X2 at planting increased grain yield considerably in each respective treatment. We found a 10- to 12-bushel-per-acre increase in the 2X2 starter treatments."

"I have found that products like AVAIL tend to be most beneficial in extreme soil pH levels," says Scott Staggenborg, professor of agronomy at Kansas State University, who oversaw Olson's study. "Jeremy's work is in an 8.2-pH soil, but other results from the region indicate a potential for responses at low soil pHs, as well."

 The benefits of AVAIL not only appear in grain yield data but visually in the plants as well, as seen in the picture below.

ABOVE: Near Manhattan, Kan. – Side-by-side comparison of AVAIL-applied corn (eight rows on left) vs. rows applied with fertilizer-only. Results showed AVAIL-treated corn averaged more than a 16.5-bushel-per-acre increase.

"One can see AVAIL contributed to plants that were darker green, taller, more mature and, overall, a better-nurtured plant," says Olson. "The plants also had bigger root masses, stalks, ears and higher yields."

Olson stresses the importance of spoon-feeding the crop nutrients it needs by applying a 2X2 starter fertilizer at planting.

"It's difficult to predict results, but I encourage growers to look at their soil test data and try AVAIL on fields with the greatest extremes in pH," says Staggenborg. "If you're uncertain of soil pH levels, get it tested as soon as possible; you cannot manage soils effectively without soil-test data."

Don't ignore micronutrients
Olson also says testing for micronutrients, such as zinc, iron and chloride, are just as important as nitrogen, phosphorus and potassium.

"Whether it's on a crop-removal system or a yield-goal system, soil testing is essential for most growers in the Midwest," he says.

Olson suggests grid-sampling a single field in a corn-soybean rotation every other year.

An emerging role
Growers' production operation is only complete when using fertilizer-efficiency products, like AVAIL and NutriSphere-N®, in combination with other conservative planting and nutrient-application practices, Olson says. He also predicts that fertilizer efficiencies and nutrient considerations will become increasingly important to enhance corn yields in the future.

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