Fall plowdown, spring preplant, and side‐dress applications of nitrogen were compared in field experiments on Brookston clay, Brookston clay loam, and Haldimand silt loam soils. Ammonium nitrate, urea, and anhydrous ammonia were compared at 56, 112, 168, and 224 kg N/ha. Spring application (preplant or side‐dress) produced higher grain yields than fall application in all experiments regardless of the rate of nitrogen applied. Preplanting the nitrogen was as effective in increasing grain yield as the side‐dress method. Yield results with fall‐applied nitrogen were poorer on the clay soil than the loam soils. Spring application of nitrogen gave 370 to 2,610 kg/ha higher yield of corn grain than fall application on clay soils, and 200 to 1160 kg/ha higher yield of corn grain on the loam soils. No rate of nitrogen applied in the fall was found that would give the same yield as the optimum rate applied in the spring. The three nitrogen materials gave similar results whether applied in the fall or in the spring.
The nitrogen content of the grain varied with the time and method of application of nitrogen. Grain from plots that received nitrogen in the fall was markedly lower in percent nitrogen than grain from plots that received nitrogen in the spring.
Ammonium phosphates providing five N:P atom ratios (1.00, 1.25, 1.50, 1.75, and 2.00:1) were applied in solution in the row with wheat seed at planting in greenhouse experiments. The soils used were Oneida clay loam (CEC 18.3 meq/100 g) and Fox sandy loam (CEC 8.2 meq/100 g) each adjusted to pH levels ranging from 5.4 to 7.4. Soil pH, over the range studied, had no effect on emergence with any of the ammonium phosphate materials tested. Neither early nor final emergence changed when the N:P atom ratio was varied in the clay loam soil when the molarity of the fertilizer solution was held constant (equal rates of P but varying rates of N). In the sandy loam soil early emergence was markedly lower with high N:P atom ratio materials than with low ratio materials. Final emergence showed the same trend as early emergence with the sandy loam soil but differences between materials were much smaller. The difference in results between the two soils is attributed to the effect of cation exchange capacity on the toxicity of ammonia in the soil.
ENH-1068, an 8-page illustrated fact sheet by James L. Gibson, Beth Bolles, Sheila Dunning, Theresa Friday, Dan Mullins, Carrie Stevenson, and Larry Williams, describes practices for nutrition monitoring and management for growers of annual floral crops. It describes essential nutrients and their translocation, provides a table of essential nutrients, and several figures showing symptoms of nutrient deficiencies. Includes a list of additional resources. Published by the UF Department of Environmental Horticulture, April 2007.
Retired from EDIS October 2020.
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