Matrix Based Fertilizers with Arbuscular Mycorrhizae Reduce Nitrogen and Phosphorus Leaching in Three Soils.
James Entry and R. E. Sojka. USDA Agricultural Research Service, Northwest Irrigation and Soils Research Laboratory, 3793 N 3600 E, Kimberly, ID 83341
We tested the efficacy of Matrix Based Fertilizers (MBF) formulated to reduce NO3, NH4 and Total Phosphorus (TP) leaching with three different soil textures in a greenhouse column study. These matrix based formulations cover 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(SO4)3and/or Fe2(SO4)2 and with matrix based high ionic exchange compounds. When N and P are released from the chemicals containing these nutrients the new matrix based fertilizers likely bind N and P to Al(SO4)3and/or Fe2(SO4)2 and the matrix. One mg (8000 spores) of Glomus intradices was added to all formulations to enhance nutrient uptake. In all three soils, 28, 49 and 70 days after fertilizer additions, OsmocoateŽ 14-14-14 a conventional, commercial slow release fertilizer (SRF) leachate contained a higher concentration and amount of TP than leachate from all other fertilizers. In all three soils, SRF leachate contained a higher concentration and amount of NH4 than leachate from all other fertilizers except MBF3 without Al(SO4)3and/or Fe2(SO4)2 and MBF2 in the loam soil. In all three soils, 28, 49 and 70 days after fertilizer placement there were no consistent differences in concentration and amount of NO3 among fertilizer leachates. MBF formulations leachates did not differ from or were lower than control leachate (no fertilizer applied). Plants growing in soils receiving SRF had greater shoot, root and total biomass than all MBF formulations regardless of Al(SO4)3 and/or Fe2(SO4)2additions. Arbuscular mycorrhazal infection in plant roots did not consistently differ among plants growing in soil receiving SRF and MBF formulations regardless of Al(SO4)3 and/or Fe2(SO4)2 additions and plants growing in soils receiving no fertilizer (control). Although these new MBF formulations resulted in lower plant growth in this experiment they may be applied to soils growing plants in areas that are at high risk for nutrient leaching to surface waters. Although field testing in necessary, results of this greenhouse test are promising. Initially these new matrix based fertilizers may only be economically feasible to high value greenhouse or horticultural or for homeowner lawns, turf grass operations such as golf courses.