ALFRED, N.Y. -- It is ironic that fertilizers that provide the nutrients necessary for plant growth sometimes pollute the environment and deplete natural resources. But a new method of producing phosphate fertilizers, patented by an Alfred University researcher, may help solve some of those problems.
Dr. Alan Goldstein, the Fierer Professor of Biology and associate director of the biomedical materials engineering sciences program at Alfred University, has developed technology he says "has the potential to revolutionize phosphate fertilizer technology by providing an environmentally safe, slow-release method of delivering elemental phosphate to crop plants."
Phosphorus is second only to nitrogen as an essential inorganic plant nutrient, Goldstein explains, making it the world's second largest agricultural chemical product. Unfortunately, current fertilizers are "wet-processed," meaning that concentrated sulfuric acid is used to extract phosphoric acid from rock phosphate ore. "This technology is both energy-intensive (one percent of the total energy consumed in the U.S. today is used to smelt phosphate ore) and environmentally polluting," says Goldstein.
In research funded by the U.S. Department of Energy, Goldstein and his colleagues at the Idaho National Engineering & Environmental Laboratory have developed and patented a new type of fertilizer that uses bacteria to "bioprocess" raw phosphate ore into fertilizer P (phosphate) right in the soil. Rather than using electricity, the energy for the bioprocess can come from waste biomass (cellulose from old newspapers or agricultural processing byproducts). As the bacteria grow inside the pellet, they use the cellulose as their energy source, first converting the cellulose to glucose and then converting the glucose to 2-ketogluconic acid, one of the strongest naturally occurring organic acids, Goldstein explains. The acid, in turn, releases soluble phosphate from the ore and this soluble phosphate diffuses out of the pellet to the plant root.
"In addition to saving energy and alleviating the pollution produced by current industrial processing, the pellet will release soluble phosphate slowly, because it's controlled by the growth rate of the bacteria," says Goldstein.
Right now, in order to ensure that plants get enough phosphate, farmers are often forced to apply excess fertilizer because the phosphate salts in them are highly water soluble, meaning they are easily washed away from the plant roots. When that happens, the excess phosphate salts either reprecipitate in the soil or move with groundwater or surface water, ending up in streams and lakes. This, in turn, causes eutrophication, or overgrowth of algae that destroys wetlands and other ecosystems.
While there are no immediate plans to produce biopellets on a commercial basis, a major agricultural chemical company continues to fund development work at Alfred University. Goldstein says he believes the growing demand for sustainable agriculture will ultimately make the biopellets a viable technology.
"During the past 40 years, nearly one-third of the world's arable land has been lost by erosion," says Goldstein, "and fertilizer run-off from midwestern farming has contributed to what may be the world's largest oceanic 'dead zone' in the Gulf of Mexico."
The National Research Council has issued two reports in the past ten years warning that we must develop new sustainable agricultural technologies. Sustainable agriculture, which protects and preserves the world's natural resources while allowing it to grow the food necessary to support human and animal life, is inevitable, Goldstein believes. "This must be the next Green Revolution," he says "and the technology we are developing here at Alfred University will ultimately play an essential role."
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