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Richard O. Carey, George J. Hochmuth, Christopher J. Martinez, Treavor H. Boyer, Vimala D. Nair, Michael D. Dukes, Gurpal S. Toor, Amy L. Shober, John L. Cisar, Laurie E. Trenholm, and Jerry B. Sartain

frequently and in larger quantities than any other fertilizer-supplied nutrient because plants require more N and it is typically the most yield-limiting nutrient. Phosphorus, another essential plant macronutrient, is required for energy reactions and is also

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Robert F. Polomski, Douglas G. Bielenberg, Ted Whitwell, Milton D. Taylor, William C. Bridges, and Stephen J. Klaine

phosphorus (PO 4 3− , H 2 PO 4 − , H 2 PO 4 2− , and H 3 PO 4− ), encourage algal growth and accelerate eutrophication, primarily in freshwater systems. Also, high levels of nitrates in drinking water can cause methemoglobinemia in infants (“Blue Baby

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Earl E. Albregts and C. K. Chandler

The phosphorus content is usually high in soils on which strawberry production occurs in west central Florida because of moderate P levels in the virgin soil and yearly applications of P by the growers. A P rate study was conducted to test the calibration of P for strawberry nursery production, and a randomized complete block design with four replicates was used. Rates of 0, 11, 22, and 33 kg/ha P were applied to a Seffner sand which had an initial soil P level of 86 mg/kg using the Mehlich II soil extractant. Soil tests routinely show P soil concentrations up to 250 mg/kg or greater with 86 mg/kg rated in the high range. In this study the P applied to the beds was cultivated into the soil and six plants of two strawberry clones (Fl 87-210 and Fl 85-4925) were set in each plot on 28 May 1991. All nutrients except P were applied as needed during the season. Leaf P content of daughter plants on 20 Aug 1991 varied from 0.23 to 0.25% among P treatments and were not different because of P rates. All marketable size daughter plants were harvested on 8 Oct 1991. The number, total wt, and average wt of daughter plants were not different because of applied P rates.

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William B. Evans and Darryl D. Warncke

Six potato cultivars (Atlantic, Sebago, Onaway, Russet Burbank, Lemhi Russet,and Norland) were evaluated for phosphorus uptake efficiency in solution culture. Individual rooted cuttings of each cultivar were transferred from a standard 1/5 Hoagland's solution into solutions containing one of six P concentrations (0.05,0.1,0.22,0.5,1.1 and 2.3mg/l). After a 24h adjustment period P uptake was followed over a 6h period by collecting solution aliquots every two hours. All cultivars depleted the two lowest initial P concentrations to similar stable P concentration. The P uptake rate per unit length of root showed a sigmoidal relationship to the initial P solution concentration. The general nature of the P uptake relation to solution P concentration was similar among the cultivars, although the actual values varied. In general, P uptake rate increased from 5.0 × 10-4 at the lowest concentration to 7.0 × 10-2μg·cm-1·h-1 at the highest P solution concentration.

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Kimberly A. Klock and Henry G. Taber

Three bone products (meat and bone meal, steamed bone meal, and bone chips) were compared to a water-soluble P source (monocalcium phosphate) for P availability and enhancement of tomato shoot growth. All bone products were finely ground to pass through a 40-mesh sieve. The products were added to a phosphorus-deficient greenhouse growing medium based on their P concentration with P at 50, 100, 200, and 400 mg·kg−1. Meat and bone meal produced the least shoot growth in 1992, but all products were similar in 1993. Growth peaked with P at 111 mg·kg−1 in 1992, but in 1993, P at 50 mg·kg−1 was sufficient. Shoot P uptake was in direct proportion to P availability in the soil mix, monocalcium phosphate having the highest shoot P content. Although bone products affected N, Ca, Zn, and Mn content in shoots, the magnitudes of differences were minor and inconsistent from 1992 to 1993. Major consideration for using a bone product are its relative cost of P, fineness of grind, and CaCO3 equivalent.

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Mohammed B. Tahboub, William C. Lindemann, and Leigh Murray

, phosphorus (P), and potassium (K) ( Table 1 ). The N content (0.34%) of the pecan wood chips used in 2002 was used to estimate the C:N ratio (143:1) of pecan wood based on an assumed 48.5% carbon content ( Lamlom and Savidge, 2003 ). Five random wood chip

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Stephanie E. Burnett, Donglin Zhang, Lois B. Stack, and Zhongqi He

. Previous research indicated that container-grown fan flowers have fewer and shorter stems, reduced leaf area, and fewer flowers when grown in substrates fertilized with more than 43.5 mg·L −1 P of ( Zhang et al., 2004 ). Phosphorus toxicity symptoms

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Kayla R. Sanders and Jeffrey S. Beasley

nutrients such as N and phosphorus (P) not only reduces soil fertility and thus turfgrass quality ( Evans and Sorger, 1966 ; Mengel and Kirkby, 1987 ), but also contributes to surface and subsurface water impairment. High nutrient concentrations are

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Ada Baldi, Anna Lenzi, Marco Nannicini, Andrea Pardini, and Romano Tesi

.8 mg·L −1 zinc sulfate heptahydrate (22.7% Zn). Table 1. Nitrogen (N), phosphorus (P), and potassium (K) rates applied to ‘Patriot’ hybrid bermudagrass grown in pots. Pots were arranged in a completely randomized design with four pots per treatments

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Salvatore S. Mangiafico, Julie Newman, Donald J. Merhaut, Jay Gan, Ben Faber, and Laosheng Wu

, 0.06 mg·L −1 ammonium (NH 4 )-N, and 0.16 mg·L −1 total phosphorus (P) ( Graves et al., 2004 ). Other studies in Florida reported mean concentrations in stormwater runoff of 0.30 to 1.4 mg·L −1 orthophosphorus (PO 4 )-P ( He et al., 2006 ) and