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FieldScience rate (1×) for the native soil plots was 147 kg/ha , consistent with rection by least significant difference following a significant F-test. ommendations for home lawns, while the target annual N rate (1×) Phosphorus saturation was calculated as: PSI = P / [Fe + Al], where for the sand/peat plots was 245 kg/ha, consistent with golf course fairP, Fe, and Al are the molar concentrations of oxalate-extractable phosway management. Fertilization was split into three equal applications phorus, iron, and aluminum in the soil. per year on the native soil plots and five applications per year on the A similar oxalate extraction and calculation was done on the two sand/peat plots. The 1.5× rate treatments received 50% more fertilizer natural organic fertilizers to determine the relative degree of P binding on each application date. with Fe and Al in each material. The organic fertilizer sources were Organic 6-7-0, made from PHOSPHORUS LEVELS AND POTENTIAL LOSSES anaerobically digested and heat-dried municipal biosolids, and a comValues for Bray-1 extractable P were significantly higher in most of mercially available Organic 8-3-5, made from mixed animal by-prodthe Organic 6-7-0 treatments when compared to the PCSCU fertilizer ucts. In the field, the Organic 6-7-0 N application rate was slightly treatment. In the native fine sandy loam soil managed as home lawn, higher than the Organic 8-3-5 rate. This was because the product was the plots receiving Organic 6-7-0 1.5× treatments were significantly originally labeled as 5% N (5-4-0), but subsequent analysis showed it higher in extractable P than the PCSCU treatment, and in the sandto be 6-7-0. Based on the fertilizers applied to each treatment on an N based fairway soil, both sets of plots receiving Organic 6-7-0 treatbasis, the amount of P added per year in the organic fertilizers ranged ments were significantly higher in extractable P than the PCSCU from 55 to 138 kg P O /ha for the Organic 8-3-5 and from 206 to treatment. 515 kg/ha for the Organic 6-7-0. The synthetic slow-release control N The plots receiving Organic 8-3-5 treatments showed a trend for source was a 20-5-10 formulation containing polymer-coated, sulfurhigher Bray 1-P than the plots receiving synthetic fertilizer, but differcoated urea (PCSCU). The P in this formulation was monoammonium phosphate. It was applied at the same N rate as Organic 8-3-5. Phosphorus rates Table 3. Bray 1-P saturation (PSIox) in the soil root zone after three years of fertilizer application, for this material were 37 kg P O /ha/year for 2008-2011. native soil managed as home lawn and 61 kg/ha/year for sand managed as a golf course fairway. For the native soil plots managed as a home lawn, fertilizer application dates were August and October 2008; May, June, and Oct 2009; April, August, and October 2010; and April 2011. For the sand-based plots managed as a golf course fairway, fertilizer application dates were August, October, and November 2008; April, June, July, September, and November 2009; March, May, a August, September, and November 2010; Low = < 20 mg/kg; medium = 20-40 mg/kg; high = 40-100 mg/kg; excessive = >100 mg/kg. Hor neck et al. (7). and March and May of 2011. b Phosphorous saturation index = Pox/ [Feox + Alox] In July of 2011, six to eight 25-mm-dic Means followed by the same letter are notsignificantly different. P = 0.05. Mean of four samples. ameter soil cores were removed to a 100Control Soil Samples (untreated areas surrounding plots) Bray-1P Test = 18mg/kg. mm soil depth from each plot. Unfertilized Table 4. Bray 1-P and P saturation (PSIox) in the sand root zone after three years of fertilizer applicontrol samples were taken at the same cation, 2008-2011. time from untreated areas surrounding the plots. Verdure and thatch were discarded. Samples were mixed, placed in paper bags, moved to a greenhouse, and allowed to air dry for 1 week. After drying the samples, they were analyzed for Bray 1-P and ammonium oxalate extractable Fe, Al, and P. This data was used to determine phosphorus saturation (PSI) in each treatment in each soil type. We also compared the effectiveness of the P fertilizers in changing Bray-1 P, calculated as the slope of the linear regression of Bray-1 P vs. total fertilizer a Phosphorous saturation index = Pox/ [Feox + Alox] b P applied. All data were analyzed using Means followed by the same letter are not significantly different. P = 0.05. Mean of four samples. Control Soil Samples (untreated areas surrounding plots) Bray-1P Test = 16mg/kg. SAS PROC ANOVA, with means separa- 12 SportsTurf | December 2013