Recent research work has produced new fertilizer recommendations for wheat, but what about corn?

Roger Ashley, North Dakota State University Extension agronomist at the Dickinson Research Extension Center, said NDSU is currently working on new nitrogen recommendations for corn.

“The current fertilizer recommendations for corn are more than 35 years old,” Ashley said.

The North Dakota Corn Council, along with other organizations, is providing funding for the project.


The reason NDSU wants to find new recommendations is:

- Corn is a major rotational crop.

“As a warm season grass, it is great one for producers to put in,” Ashley said.

With no-till, there could be different recommendations for corn than were designed for tillage systems in the past.

With today’s hybrids and cultural practices, new recommendations are needed to keep producers profitable and avoid undue environmental scrutiny.

-Corn uses a lot of nitrogen.

“Nitrogen is one of the largest inputs needed for (growing) this crop, and it is a big cost in producing corn,” Ashley said.

He added 35 years ago, it wasn’t a big deal to use a lot of nitrogen at 8 to 12 cents a pound. Today, at 30 to 40 cents a pound, it is much more costly. According to the study, Ashley said today’s major corn farms average 160 pounds of nitrogen per acre for corn.

This study began in 2010 but will go to 2012 across many sites in all regions of the state, including two no-till sites on farms in southwestern North Dakota.

“We really need about three years of data to make the information usable,” Ashley said.

The two sites in southwestern North Dakota were more consistent than data obtained from more eastern sites this past summer.

“There are a lot more things affecting nitrogen response in eastern North Dakota,” he said.

Soil testing indicating the site at Beach, N.D., had 46 pounds per acre and the New Leipzig, N.D., site had 38 pounds per acre soil nitrate-nitrogen prior to the addition of the N treatments.

In the treatment studies this year, nitrogen was applied in six treatments at 40 pounds N per acre; 120 pounds N per acre; 160 pounds N per acre and 200 pounds N per acre.

The farmer seeded the corn, applied herbicides and other chemicals and the study was monitored throughout the growing season.

With the application of 40 pounds of N per acre, grain yield was 86.6 bushels per acre at Beach and 93.4 at New Leipzig. At 80 pounds per acre, yield was 90.5 bushels at Beach and 89.7 at New Leipzig. At 120 pounds per acre, yield was 94.4 bushels at Beach and 94.3 at New Leipzig.

At 160 pounds per acre, yield was 92.2 bushels at Beach and 101.7 at New Leipzig, and at 200 pounds per acre, yield was 101.9 bushels at Beach and 97.3 at New Leipzig.

Producers need to evaluate if putting on extra N is bringing them returns. When corn is $3 a bushel, adding nitrogen at 30 cents a pound is an additional expense, Ashley said.

“Corn prices today are close to $5 bushel. At $5 a bushel, if N is 40 cents a pound, it is much more price sensitive than the old model,” Ashley said.

By 2013, Ashley expects to have new recommendations for applying nitrogen on corn. Until then he suggest producers use the old model which is 1.2 pounds of N times yield goal minus the credit for nitrogen in the soil.