MATRIX BASED FERTILIZERS REDUCE NITROGEN AND PHOSPHORUS LEACHING IN THREE SOILS

Authors: Entry, James; Sojka, Robert

Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2007
Publication Date: 5/1/2008
Citation: Entry, J.A., Sojka, R.E. 2008. Matrix based fertilizers reduce nitrogen and phosphorus leaching in three soils. Journal of Environmental Management. 87:364-372.

Interpretive Summary: We tested the efficacy of matrix based fertilizers (MBFs) formulated to reduce nitrate, ammonium and total phosphorus leaching, with Osmocoate® 14-14-14, a conventional commercial slow release fertilizer (SRF) and an unamended control in three different soil-peat moss textures in a greenhouse column study. The MBFs 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 aluminum sulfate and 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 likely bind nitrogen and phosphorus to a aluminum sulfate and iron sulfate - starch- chitosan- lignin matrix. One milligram (8000 spores) of Glomus intradices was added to all formulations to enhance nutrient uptake. In all three soil peat moss textures, 28, 49 and 70 days after fertilizer additions, the SRF leachate contained a higher amount of total phosphorus than leachate from all other fertilizers. In all three soils, SRF leachate contained a higher amount of ammonium than leachate from all other fertilizers except MBF3 without aluminum sulfate and iron sulfate and MBF2 in the loam soil. In all three soils, 28, 49 and 70 days after fertilizer placement there were no consistent differences in the amount of nitrate among fertilizer leachates. Plants growing in soils receiving SRF had greater shoot, root and total biomass than all MBFs regardless of aluminum sulfate and iron sulfate additions. Arbuscular mycorrhazal infection in plant roots did not consistently differ among plants growing in soil receiving SRF, MBFs and control treatments. Although the MBFs resulted in less 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 is necessary, results of this greenhouse test are promising. Initially these new matrix based fertilizers may only be economically feasible in high value greenhouse or horticultural operations or for homeowner lawns and golf courses.

Technical Abstract: We tested the efficacy of matrix based fertilizers (MBFs) formulated to reduce nitrate, ammonium and total phosphorus leaching, with Osmocoate® 14-14-14, a conventional commercial slow release fertilizer (SRF) and an unamended control in three different soil-peat moss textures in a greenhouse column study. The MBFs 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 aluminum sulfate and 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 likely bind nitrogen and phosphorus to a aluminum sulfate and iron sulfate - starch- chitosan- lignin matrix. One milligram (8000 spores) of Glomus intradices was added to all formulations to enhance nutrient uptake. In all three soil peat moss textures, 28, 49 and 70 days after fertilizer additions, the SRF leachate contained a higher amount of total phosphorus than leachate from all other fertilizers. In all three soils, SRF leachate contained a higher amount of ammonium than leachate from all other fertilizers except MBF3 without aluminum sulfate and iron sulfate and MBF2 in the loam soil. In all three soils, 28, 49 and 70 days after fertilizer placement there were no consistent differences in the amount of nitrate among fertilizer leachates. Plants growing in soils receiving SRF had greater shoot, root and total biomass than all MBFs regardless of aluminum sulfate and iron sulfate additions. Arbuscular mycorrhazal infection in plant roots did not consistently differ among plants growing in soil receiving SRF, MBFs and control treatments. Although the MBFs resulted in less 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 is necessary, results of this greenhouse test are promising. Initially these new matrix based fertilizers may only be economically feasible in high value greenhouse or horticultural operations or for homeowner lawns and golf courses.