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Erin Agro and Youbin Zheng

nitrate nitrogen (NO 3 – -N), less than 0.50 mg·kg −1 ammonia nitrogen (NH 3 -N), 7.77 mg·kg −1 P, and 168.68 mg·kg −1 K (analyzed using a saturated paste extraction method by SGS Agri-Food Laboratories, Guelph, Ontario, Canada). Polyon ® 16N–2.6P–10K

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Marisa T. Potter, Richard J. Heerema, Jill Schroeder, Jamshid Ashigh, Dawn VanLeeuwen, and Cheryl Fiore

stage at the discretion of the orchard owner. Insecticide application, fertilization, and periodic mowing were all controlled by the orchard owner. Nitrogen was applied in the irrigation water during the growing season as urea–ammonium nitrate (UAN, 32

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Elizabeth A. Wahle and John B. Masiunas

PhD degree. The research was supported by funds from Hatch project #65-0334 of the Univ. of Illinois Agricultural Experiment Station. We thank John Swiader and Richard Mulvaney for the use of their laboratories to conduct the nitrogen analysis.

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Sueyde F. de Oliveira, Paul R. Fisher, Jinsheng Huang, and Simone da C. Mello

tissue dry weight and nutrient content, chlorophyll analysis, and number of flowers. Nitrogen uptake efficiency was calculated from leaf tissue. Total N content in oven-dried ground plant tissue samples was determined by Quality Analytical Laboratories

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Guihong Bi, William B. Evans, James M. Spiers, and Anthony L. Witcher

pellets such as a Georgia- and Mississippi-based company whose products include a balanced 3-3-3 and a more nitrogen-rich 4-2-2 formula. Despite having lower nutrient concentrations than many synthetic fertilizers, similar broiler litter-based fertilizers

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Brian E. Jackson, Robert D. Wright, and Mark M. Alley

; Wright and Browder, 2005 ). In contrast to peat and PB, plant production in substrates composed of wood, or large portions of wood, have a tendency to become nitrogen (N) -deficient as a result of high rates of N immobilization ( Handreck, 1991 , 1993

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Haley Rylander, Anusuya Rangarajan, Ryan M. Maher, Mark G. Hutton, Nicholas W. Rowley, Margaret T. McGrath, and Zachary F. Sexton

buried. This research assessed the efficacy of using black plastic tarps to advance reduced-till systems by analyzing the effects of black tarps on the following: 1) the soil environment, including soil temperature, moisture, and inorganic nitrogen

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Xiaojie Zhao, Guihong Bi, Richard L. Harkess, Jac J. Varco, and Eugene K. Blythe

( Lockatell and Spoon, 2011 ). However, limited information is available regarding how N rate affects spring N uptake and use efficiency in TB iris. Nitrogen plays an important role in plant growth and development. Insufficient N supply restricts plant growth

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William Garrett Owen

Table 1 . For all analyses, a P ≤ 0.05 was used to determine significant effects. Table 1. Regression models, equation, and adjusted- R 2 for sufficiency ranges of macronutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium

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T.K. Hartz and P.R. Johnstone

Limited soil nitrogen (N) availability is a common problem in organic vegetable production that often necessitates in-season fertilization. The rate of net nitrogen mineralization (Nmin) from four organic fertilizers (seabird guano, hydrolyzed fish powder, feather meal, and blood meal) containing between 11.7% and 15.8% N was compared in a laboratory incubation. The fertilizers were mixed with soil from a field under organic management and incubated aerobically at constant moisture at 10, 15, 20, and 25 °C. Nmin was determined on samples extracted after 1, 2, 4, and 8 weeks. Rapid Nmin was observed from all fertilizers at all temperatures; within 2 weeks between 47% and 60% of organic N had been mineralized. Temperature had only modest effects, with 8-week Nmin averaging 56% and 66% across fertilizers at 10 and 25 °C, respectively. Across temperatures, 8-week Nmin averaged 60%, 61%, 62%, and 66% for feather meal, seabird guano, fish powder, and blood meal, respectively. Cost per unit of available N (mineralized N + initial inorganic N) varied widely among fertilizers, with feather meal the least and fish powder the most expensive.