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Heidi J. Johnson, Jed B. Colquhoun, and Alvin J. Bussan

large scale. Nitrogen management in large-scale production is a challenge to growers, particularly for crops such as sweet corn that require large amounts of N for optimal production (150 lb/acre) ( Laboski et al., 2006 ). Nitrogen can be a costly input

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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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Lenny Wells, Jason Brock, and Tim Brenneman

, intracellular sulfate does not become highly concentrated immediately after S application ( Barker and Pilbeam, 2007 ). Table 3. Mean leaf nitrogen (N) concentration, leaf sulfur (S) concentration, and Soil Plant Analytical Development leaf chlorophyll indexes

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Sarah A. White

concentration of nutrients in container nursery (crops produced in open systems, without permanent cover) effluent can range from 0.1 to 135 mg·L −1 nitrate-nitrogen (NO 3 -N) and 0.01 to 20 mg·L −1 phosphate-phosphorus (PO 4 -P) ( Huett et al., 2005 ; Taylor

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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.

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Kate A. Ivancic, Matthew D. Ruark, Francisco J. Arriaga, and Erin M. Silva

cover crop treatment in 2014 and 2015. For the BC + O treatment, the oat and berseem clover were planted and counted separately, and the plant height was not measured (NM). Table 2. Cover crop biomass, nitrogen (N) content, N yield, and carbon (C

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Alison L. Reeve, Patricia A. Skinkis, Amanda J. Vance, Jungmin Lee, and Julie M. Tarara

. There were no crop level effects on tissue N except in one instance. Table 2. Petiole and leaf blade nitrogen concentrations (%) at bloom and véraison from 2011 to 2013 by vineyard floor management treatments. Other than N, there were few consistent

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

when production is not managed appropriately ( Schoene et al., 2006 ). The resulting runoff can be discharged from production areas and pollute surface and groundwater. Excess nutrients, notably nitrate–nitrogen (NO 3 − N) and soluble reactive

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Kayla R. Sanders and Jeffrey S. Beasley

fertilizer (control), a controlled-release fertilizer (CRF) applied at 87 lb/acre (97.5 kg·ha –1 ) nitrogen (N) at 0 d after initial fertilization (DAIF), or a water-soluble fertilizer (WSF) applied at 87 lb/acre N as a split application [43.5 lb/acre (48

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Martin P.N. Gent

to a nitrogen-free solution for 2 or 3 d lowered leaf nitrate and increased ascorbic acid ( Mozafar, 1996 ). A switch to ammonium in a nutrient film production system decreased growth, nitrate, and oxalate, but increased dry matter content ( Elia et