Our Insights | Plant Nutrition
February 26, 2016

Nitrogen Study

We strive to bring you science-based information to increase your farming operation’s return on investment through maximizing nutrient utilization and minimizing environmental impact. Our nitrogen study for 2015 incorporates customary nitrogen products, rates of nitrogen, placement methods, and timing of applications. Tillage practices and the use of a winter cover crop of cereal rye grass were also incorporated into the nitrogen trials to further evaluate each nitrogen practice.

Getting nitrogen right to meet the needs of the corn plant was a challenge in 2015 due to the wettest June on record at Pleasant Plains. As the yield graph and photograph demonstrates, this 192 trial comparison of the 4 R’s of nitrogen management point to some attractive practices that improve ROI and efficiency.

A fall ammonia application with inhibitor followed by banding 28% nitrogen and sulfur in the spring at planting time provided the most efficient nitrogen program in all tillage systems. The same rate of ammonia with inhibitor applied in the spring resulted in a 3% yield reduction when averaged over all tillage systems.

28% nitrogen as the primary nitrogen source provided the lowest average yield in comparison to ammonia, although banding 28% at plant significantly improved the efficiency. 28% nitrogen efficiency was reduced drastically as tillage was removed. Corn residue and cover crop allelopathy (the chemical inhibition of one plant or other organism by another, due to the release into the environment of substances acting as germination or growth inhibitors) reduced the corn emergence and growth in the no till system used with 28% application. (Read more about allelopathy on page 25.)

Averaging 249 bu/ac, fall ammonia in combination with 25-0-0-8S banded at plant scored a very efficient “.86” N.U.E. (nitrogen unit efficiency). The long standing university guideline for N.U.E. has been 1.2 units of N per bushel of corn.