| [Image: dustin harrell giving field day tour] |
| [Image: rice test plots] |
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LSU AgCenter agronomist Dr. Dustin Harrell of the AgCenter’s Rice Research Station conducts a wide range of research to figure out how farmers can get the most effective benefits from fertilizer applications.
Each year Harrell conducts nitrogen studies on specific varieties of rice to learn the optimum amount. He said the 2008 work with nine varieties included Catahoula and Neptune in addition to the potential variety LA2125.
The testing is conducted in research plots in North and South Louisiana.
Harrell said the most cost-effective amount of fertilizer can vary widely from variety to variety – anywhere from 90 to 180 pounds per acre.
Water management is a key issue that can affect nitrogen use efficiency in rice. Research shows nitrogen is best applied when the soil is dry and then followed immediately with a flood.
Harrell said his research includes the use of the GreenSeeker, an optical sensor that measures the midseason nitrogen status of the rice, and once calibrated with several years of research will potentially be able to provide real-time recommendations for midseason fertilization. Working with Harrell on the project are Dr. Brenda Tubana, LSU AgCenter assistant professor of soil fertility, and Dr. Tim Walker, an agronomist from Mississippi State University.
"Hopefully within three years we will have some good information as to its utility for use in rice production," Harrell said.
Harrell said with the increasing costs of fertilizers, an $8 soil test is still one of the best ways to make sure farmers are spending the correct amount of money on nutrients. "It could save a considerable amount of money," he stressed.
His work also examines nutrient applications on the ratoon crop. Harrell said it’s best to apply nitrogen immediately after harvest, but many farmers wait to see if the stubble appears to show potential before fertilizing.
Harrell said he also conducts work to find out which stubble-management techniques will improve second-crop yields.
In most years, he said, leaving a short stubble when harvesting the first crop results in a higher-yielding ratoon crop. Flail mowing also will improve yields, he said, but it requires a farmer to spend more money on diesel fuel because flail mowing requires a second trip across the field.
Next year he also plans to evaluate different stubble-management practices, with and without fungicide application, in an effort to evaluate if some of the yield advantage to stubble management may be related to reduced disease pressure.
Harrell said his work in 2008 included trials that evaluated zinc fertilization sources, application rates and timing of application on a field with a historic localized decline problem. From the first year of data he found that using zinc sulfate at a rate of 5 pounds of zinc per acre increased yields and reduced leaf bronzing symptoms. The farmer involved in the study reported his highest yield ever on that field, Harrell said.
"Adding zinc many not always be the solution, but at that field it was. There’s still a lot of work to do on this problem," Harrell said. –Bruce Schultz
Checkoff funds for this project: $120,000