Story by Fred Miller
FAYETTEVILLE, Ark. — The University of Arkansas System Division of Agriculture revised its recommendations for phosphorus fertilizer applications to soybean fields in 2010 and Division scientists expect further revisions in the near future.
“In ongoing research funded primarily by the Arkansas Soybean Promotion Board, we’ve had close to 50 different experiments over the last eight years,” said Nathan Slaton, professor of soil fertility. “What we were seeing is that soybeans are not highly responsive to phosphorus fertilizer.”
The Division presently recommends adding 40 to 80 pounds per acre of P205 phosphorus fertilizer to soils containing up to 35 parts per million of phosphorus, Slaton said. Phosphorus applications are not recommended for soil test levels above that threshold of 35 ppm.
In 2010, the division reduced the recommended amount of phosphorus fertilizer by 20 pounds of P205 per acre for soils having less than 35 ppm, Slaton said.
Based on 2011 research, Slaton said he expects soil test levels will be reinterpreted to lower the thresholds at which phosphorus fertilizer application is recommended.