27 November 2007

3 minute read

North America

This is according to South Dakota State University Soils Testing Lab Manager Ron Gelderman, who suggests soil testing as the first, and best, action producers can take.

"Producers concerned about high fertilizer costs and not soil sampling are not really serious about saving money," Gelderman said. "Composite soil sampling and testing is quick and inexpensive." Gelderman notes the following points are important to consider in soil sampling:

• Use a two-foot nitrate-N test for fields going into a non-legume crop
• Use yield maps in stressed corn-on-corn field to determine yield-sample areas which may save some nitrogen costs
• Use topography-sample areas that may provide P, K, Zn, and S savings
• Areas that once were feedlots or farmyards should be sampled separately.

Producers can consider planting legumes since they fix their own nitrogen needs, and Gelderman said producers also should consider banding phosphate.

"For medium- and high-testing phosphate soils, consider banding one-half the recommended broadcast P, and for low- and very-low-testing soils, broadcast one-half the recommended P and band one-half of the remaining amount."

Most of the research shows this action will result in similar yields and minimally reduce the soil phosphate levels, Gelderman said.

Nitrogen application timing can save, and producers need to consider nitrogen credits as well, Gelderman said. Nitrogen application at planting or later is often the best choice. When possible, look at alternatives like anhydrous ammonia instead of urea, and the value of manure utilization.

"If possible, apply manure on fields with lower P and K levels," he said. "Then apply the manure to meet your crop nitrogen needs." Consider selling manure if your field P and K values are high, and use the money from the sale towards N-only fertilizer.

Realistic yield goals, along with practical application methods will save producers money as well, Gelderman said. Average five years' of yield data after omitting yield values that looks abnormally high or low. Then set a goal of exceeding the average by 10-15 percent. With application practices, watch techniques and consider factors such as the following:

• Make sure the application furrow is closing well when using anhydrous ammonia
• Incorporate urea, or in no-till situations, apply in early to mid-spring
• Consider using a sub-surface or surface band application with urea or UAN on no-till fields to reduce loss and residue tie-up
• Only in special cases will nitrification and urease inhibitors and controlled-nitrogen release products show an advantage over standard materials.

Gelderman says producers should select fields with high carry-over levels of nitrogen for corn-on-corn planting and consider soybeans for fields with lower carry-over.

He also reminds producers "not to panic and avoid cutting nutrient inputs randomly," he said. "Even with record high prices, you can still get very good returns adding nutrients where they are needed."

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