How much nitrogen is too much for corn?

Apr 23, 2007

North Carolina State researchers recently discovered a test that quickly predicts nitrogen levels in the humid soil conditions of the southeastern United States. These scientists report that the Illinois Soil Nitrogen Test (ISNT) can assess the nitrogen levels in soil with more accuracy than current soil-based tests. This test will allow growers to cut back on the amount of nitrogen-based fertilizer added to soil, leading to economic and environmental benefits.

The proper management of nitrogen is critical to the success of many crop systems. Based on an assessment of the natural amount of nitrogen in soil, growers calculate their optimum nitrogen rates, the concentration of nitrogen that must be present in fertilizer in order to achieve expected crop yields. Under- and over-applying nitrogen fertilizer to corn crops often leads to adverse economic consequences for corn producers. Excess levels of nitrogen in nature also pose serious threats to environment. Agricultural application of nitrogen has been linked to rising nitrate levels and subsequent death of fish in the Gulf of Mexico and North Carolina’s Neuse River.

"Although offsite nitrogen contamination of ground and surface waters could be reduced if nitrogen rates were adjusted based on actual field conditions, there is currently no effective soil nitrogen test for the humid southeastern U.S.," said Jared Williams, lead author of the North Carolina State study that was published in the March-April 2007 issue of the Soil Science Society of America Journal. This research was supported in part by USDA Initiative for Future Agricultural and Food Systems (IFAFS) grant.

From 2001 to 2004, scientists collected and tested the soil from 35 different sites in North Carolina. According to the North Carolina scientists, the collected soil samples were representative of millions of hectares in agricultural production in the southeastern USA. Corn was planted at each site with a range of nitrogen fertilizer rates, and the optimum nitrogen rates and the soil assay results were compared among the sites.

From the collected samples, researchers discovered that the Illinois Soil Nitrogen Test (ISNT) could be used to accurately measure the economic optimum nitrogen rates (EONR) of southeastern soils, despite moderate weather variation over the collection period. While the test can be used to predict the optimum nitrogen rates, the relationship between ISNT and EONR varied by soil drainage class. Researchers believe that these differences represent differences in organic matter that lead to less mineralization and/or more denitrification on poorly drained soils. The results indicate that the Illinois Soil Nitrogen Test can serve as a model for predicting economic optimum nitrogen rates on well- and poorly drained soils and show promise as a tool for nitrogen management.

"Additional research is needed to calibrate and validate the EONR versus ISNT relationships under a wider variety of conditions," says Williams. "Because the Illinois Soil Nitrogen Test predicted EONR robustly to different cost/price ratios, ISNT has the potential to modify or replace current nitrogen recommendation methods for corn."

Source: American Society of Agronomy

Explore further: "Light pollution" may affect love lives of birds in the Viennese Forests

add to favorites email to friend print save as pdf

Related Stories

P90X? Why consumers choose high-effort products

6 minutes ago

Stuck in traffic? On hold for what seems like an eternity? Consumers often face situations that undermine their feelings of control. According to a new study in the Journal of Consumer Research, when a person's sense of con ...

Overdoing it: Multiple perspectives confuse consumers

23 minutes ago

Television commercials for luxury vehicles pack a lot in their 30-second running times: the camera offers quick shots of the soft leather upholstery, the shiny colors, the state-of-the-art entertainment system, ...

Recommended for you

Monkeys fear big cats less, eat more, with humans around

1 hour ago

Some Monkeys in South Africa have been found to regard field scientists as human shields against predators and why not if the alternative is death by leopard? The researchers found the monkeys felt far safer ...

Study indicates large raptors in Africa used for bushmeat

15 hours ago

Bushmeat, the use of native animal species for food or commercial food sale, has been heavily documented to be a significant factor in the decline of many species of primates and other mammals. However, a new study indicates ...

The microbes make the sake brewery

16 hours ago

A sake brewery has its own microbial terroir, meaning the microbial populations found on surfaces in the facility resemble those found in the product, creating the final flavor according to research published ahead of print ...

Fighting bacteria—with viruses

17 hours ago

Research published today in PLOS Pathogens reveals how viruses called bacteriophages destroy the bacterium Clostridium difficile (C. diff), which is becoming a serious problem in hospitals and healthcare institutes, due to its re ...

User comments : 0