The use of fertilizer in rice has come a long way since USDA and Louisiana Agricultural Experiment Station scientists began performing experiments at the LSU AgCenter Rice Research Station 100 years ago this spring.
“Most of the first rice crop planted on the station in 1909 was not fertilized at all,” said Justin Harrell, an LSU AgCenter agronomist based at the current Rice Research Station east of Crowley, La., who spoke at the station’s Centennial observance on July 1.
“A select few of the cuts were fertilized with 200 pounds of acid phosphate and 50 pounds of nitrate of soda, both common fertilizers available at the time. We don’t know why J. Mitchell Jenkins, the first rice breeder at the station, did not fertilize all of his rice that year. Perhaps the cost was prohibitive or he only had a limited supply of the fertilizer.”
Acid phosphate fertilizer is also known as superphosphate, which is made by treating rock phosphate with sulfuric acid, Harrell told participants at the field day held in conjunction with the Centennial. The nitrate of soda was a 16 percent nitrogen source, which was mined in the Chilean desert and imported into the United States.
In the first 20 years, potassium fertilizers were relatively expensive because they had to be imported. “Some K fertilizers were available from wood ashes, cottonseed hulls and tobacco stems, however, most K had to be imported from Germany where K-bearing minerals were being mined from K-rich brine deposits as early as 1839,” he said.
“After America’s entry into World War I in 1917, imports of K fertilizer from Germany were halted, and we began to search for our own sources of potassium minerals. This search led to the discovery of potash deposits in Carlsbad, N.M., in 1925 and in Searle’s Lake in California around the same time.”
World War II also had ramifications for the U.S. fertilizer industry. As America’s involvement in the war escalated, production of solid ammonium nitrate skyrocketed because it could be used as an explosive for bombs. Additional plants were erected to increase production, and ammonium nitrate was stockpiled.
“After the war, the oversupply of fertilizer was made available for agriculture use, which really jumpstarted the N fertilizer by supplying farmers with an affordable source of N,” said Harrell. “The war also helped create a new delivery method for fertilizers and other farm chemicals as pilots trained during the war returned home and began looking for jobs.”
The roster of scientists who have held Harrell’s position at the Rice Research Station reads like a who’s who of rice fertility specialists. Besides Jenkins, who was primarily a rice breeder, the list has included Rufus W. Walker; D. Marlin Brandon; Patrick Bollich, now resident director of the Central Research Station in Baton Rouge; and Jason Bond, now a weed scientist with the Delta Research and Extension Center in Stoneville, Miss.
Harrell says the tradition of nutrient and cultural management research continues at the Rice Research Station with the collaboration of rice nutrient management scientists from other rice-producing states.
He and Rick Norman, rice fertility specialist at the University of Arkansas, said scientists are working on two promising technologies — the use of canopy reflectance measurements to evaluate the midseason N needs of rice and a rice nitrogen soil test, which would allow farmers to apply nitrogen to rice on a field-by-field basis.
“Rice researchers have developed a method for measuring the amount of N a silt loam soil will mineralize during the rice growing season,” said Harrell. “This method enables an N fertilizer rate recommendation not just based on soil texture, previous crop and cultivar, but on an individual field-by-field basis. We’re conducting validation experiments on the new rice nitrogen soil test to evaluate its robustness.”