Matrix-based fertilizers: A new fertilizer formulation concept to reduce nutrient leaching

We compared the efficacy of matrix based fertilizers (MBFs) formulated to reduce NO 3 -, NH4+ , 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 Al(SO 4)3 H2O and/or Fe2(SO4 )3 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 Al(SO4 )3 H2O and/or Fe2(SO4 )3 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 NH4+ , NO3 " 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 NH4+ , NO3 - 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.