Fertilizer recommendations for Louisiana rice largely come from agronomy research done at the Rice Research Station in Crowley, La.
“We changed the system a bit a couple of years ago,” said Jason Bond at the Rice Research Station field day in Crowley. “A split application was employed so we apply 90, 120, 150 or 180 pounds of nitrogen immediately prior to the flood. Then, we began going back with a topdress of 0, 30, or 60 pounds of nitrogen at mid-season.”
Last year, Bond — an agronomist who recently left the Crowley station for the Delta Research and Extension Station in Stoneville, Miss. — finished up studies on the “last wave of varieties released a few years ago. Since then, we've begun studying a few new ones.
“The four commercial varieties (in the test) this year: CL131, Trenasse, medium grain Jupiter, and a very early variety out of Arkansas called Spring. Also, three of (Crowley station director and rice breeder) Steve Lincombe's experimentals are entered this year.”
The second part of the program is ratoon research. Last year, Hurricane Rita ruined most of the ratoon studies.
“We didn't get to cut a lot of the studies we began in 2005 and were excited about. No data was generated by our ratoon research last year.”
But Bonds is trying again with tests looking at different stubble manipulations, flail mowing and rolling.
“We're putting some N out in the main crop after heading to try and boost the growth of the second crop. We're screening some different herbicides along with other things on both conventional varieties and hybrids.”
An interesting thing Bonds reported seeing this year is a seeding rate test with Cheniere, CL 131 and Wells. The experiment is being done cooperatively with all the rice-producing states.
“On those three varieties, we're planting as low as 7.5 seed per square foot. In general, that's less than 20 pounds per acre. We go all the way up to 150 pounds per acre.
“Seeding rates have gone down recently. And the small plot research says we can stretch it even lower when the situation can be controlled closely…So if we're going with a lower seeding rate, can we also go with less N or do we need to go with more N to compensate for the lower populations?”
In Mississippi, “growers are probably 99 percent-plus drill-seeded, delayed flush culture,” said Tim Walker, a MSU rice agronomist at the Delta Research and Extension Station in Stoneville, Miss., at the field day. “Many (Louisiana producers) are probably doing work with a water-seeded system.”
One of the newest projects Walker has begun involves research data on semi-dwarfs. Studies have shown “if higher rates of N pre-flood pretty much set the yield. The rice won't be as responsive to a mid-season application.”
In Mississippi and other states doing a lot of drill-seeded rice, “we often put out N or other mixed fertilizers when rice reaches one-leaf or two-leaf stage. Usually, if it's not raining, we'll have to flush to incorporate herbicides.
“For many years, it's been common practice to put out some N at that time and flush it across or just in front of a rain.
“So what we're doing — especially with today's N economics, and I don't see them getting much cheaper — is evaluate those applications. To do that, we're checking how much N from those early season applications actually make it into the plant. If we can decrease N from mid-season and move it to the front end, it may be more economical.”
Research shows a 2-inch to 3-inch height difference when the N is put out at the one-leaf to two-leaf timing.
“We have some promising results and this work is also being done in Arkansas and Missouri.”
Mississippi rice producers have done a tremendous amount of land forming — something Walker has seen more of in south Louisiana.
“Anytime you've got shallow soils and are removing topsoil, you'll have soil issues. I've been involved with that over the last seven years to help restore precision-leveled fields back to optimum production.
“In our situation, most of the time there's a problem it has to do with fertility. We'll scrape away the topsoil and get into low-fertility subsoil. So, we're looking at the different mixed fertilizers — P, K, zinc and those sorts of things. On cut soil problems, primarily phosphorus and zinc have been the limiting factors.”