Making Smart Fertilizer Recommendations in Today’s Market
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Making Smart Fertilizer Recommendations in Today’s Market

December 04, 2008   |   ShareThis

Last year the economics of growing corn, wheat and soybeans were excellent. Worldwide supplies of N, P, and K were tight. Now, with grain prices down 40-50%, farmers around the world have cut back fertilizer use--in South America and Latin America they've cut 40-60% due to credit issues. Only India and Australia are increasing fertilizer usage. The result is a worldwide stockpile of P and more K available than last year.

On the local front, dealer storage is full due to both higher prices and late harvest combined with poor weather preventing fall application. Growers are waiting to see how low prices will go before they buy. If corn prices rise and more corn acres are planted, application logistics and availability of enough P & K may challenge spring application.

Despite all these factors, there are two fundamental approaches to helping growers make fertilizer decisions: managing input costs and the consequences of not applying. Let's look at managing costs.

First, help your customers set realistic yield goals. Today's hybrids have much greater yield potential. They require a higher amount of nutrients to reach their full potential and deliver the return on investment the grower deserves.   

Know what nutrients are available in the soil. A soil test is an invaluable investment in the production decision process. Compare the nutrients available to what the plant needs to reach the desired yield goal and yield potential. Growers often attempt to rely on nitrogen only. They forget potassium interacts with almost all essential plant food nutrients and "regulates" many essential plant processes including enzyme activation, photosynthesis, water use efficiency, starch formation and protein synthesis. Without K, plants cannot optimize their uptake of available N. So, money spent on N may be wasted. Ohio State research demonstrated that corn yields were reduced by 44 bushels/acre when high levels of N were used on fields with inadequate K levels. At $3.75 corn, the foregone bushels would cost the grower $165 per acre.

Likewise, adequate P is necessary for higher yields and improved grain quality because P also improves the plants' ability to use all available nutrients. The critical level of P in the soil is 20 ppm. Without phosphorus fertilizers added to balance nutrition, plant uptake of added nitrogen is reduced. As a result, nitrate levels in the soil increase, and some of the N investment is lost.     

 Help your customers analyze ROI by taking into consideration all input costs compared to the potential yield, with and without adequate fertilizer. Though situations vary, a field testing 10 ppm that did not receive phosphorus fertilizer would be expected to yield 20% less than a field with soil P levels at the critical 20 ppm level. It generally requires 18 pounds of P205 to raise soil test levels 1 ppm, so180 pounds of P205 per acre would be required to reach the 20 ppm level. Compare the cost of fertilizer to 20% less yield. 

Even with today's fertilizer prices and lower corn prices, a grower should receive a return on investment in fertilizer.

By Dan Froehlich, Agronomist, Mosaic Company