Author
 |
Sojka, Robert |
|
ENTRY, JAMES - U.S. PARKS SERVICE |
|
Submitted to: Proceedings of the New Zealand Lime and Fertilizer Institute Workshop
Publication Type: Proceedings Publication Acceptance Date: 2/8/2007 Publication Date: 7/1/2007 Citation: Sojka, R.E., Entry, J.A. 2007. Matrix-based fertilizer: A new fertilizer formulation concept to reduce nutrient leaching. In: Currie, L.D., Yates, L.J., editors. Proceedings of the Fertilizer & Lime Research Centre Workshop. Designing Sustainable Farms: Critical Aspects of Soil and Water Management, February 8-9, 2007, Palmerston North, New Zealand. p. 67-85. Interpretive Summary: Leaching losses of fertilizer nutrients account for a significant portion of the nutrient loading that adversely affects groundwater quality, and through spring upwelling, of surface water contamination as well. Existing commercial fertilizer formulations aimed at combating leaching losses have relied primarily on coating of fertilizer particles. The coating is usually either a sulfur or a polymer coating, designed to prevent the fertilizer from becoming completely soluble in soil moisture at the time of application. Ideally the coating would gradually degrade, slowly releasing the nutrients. In reality, most coating-dependent slow release fertilizers see the coating of most particles occur at about the same time. And when the coating fails the nutrients in the fertilizer particles are released rather quickly. Matix-based fertilizers use a combination of ion adsorption and chemical fixation to slow the solublization of N and P compounds. In greenhouse experiments Matrix based fertilizers have significantly reduced the amount of nutrients lost via leaching. Matrix based fertilizers provide an entirely new approach to providing plant nutrients while protecting water quality. Technical Abstract: We compared the efficacy of matrix based fertilizers (MBFs) formulated to reduce nitrate, ammonium, and total phosphorus (TP) leaching, with Osmocoate® 14-14-14, a conventional commercial slow release fertilizer (SRF), and with an unamended control in greenhouse column studies. The MBF formulations covered a range of inorganic N and P in compounds that are relatively loosely bound (MBF1) to more moderately bound (MBF2) and more tightly bound compounds (MBF3) mixed with aluminum sulfate and/or iron sulfate and with high ionic exchange compounds starch, chitosan and lignin. When N and P are released, the chemicals containing these nutrients in the MBF temporarily bind N and P to a aluminum sulfate and/or iron sulfate starch- chitosan- lignin matrix. One milligram (8000 spores) of Glomus intradices was added to all formulations to attempt to enhance nutrient uptake. In this first series of experiments, soil columns were planted to white soft spring wheat (Triticum aestivum L.cv. Frame). Three soils were used, a sand, a loam and a loamy sand. In several studies, SRF leachate contained higher amounts of nitrate, ammonium, and TP than leachate from all other fertilizers. Although plant biomass and yield with MBF was reduced in the first series of experiments, follow-up studies have shown that formulation adjustments allow comparable plant responses among SRF and MBFs. There were no consistent differences in the amount of nitrate, ammonium, and TP in the MBF leachates compared to the control leachate. Arbuscular mycorrhizal infection in plant roots did not consistently differ among plants growing in soil receiving SRF, MBFs and control treatments. The efficacy of MBF fertilizer strategy to reduce N and P leaching to surface has been verified and with continued work to optimize formulations this technology is expected to provide a new approach for groundwater protection, especially in easily drained soils. The approach has been submitted for patenting. |
