Crop Response to Phosphate Fertilizers as Influenced by Level of Phosphorus Solubility and by Time of Placement Prior to Planting
1958
Norland, M. A. | Starostka, R. W. | Hill, W. L.
Several commercial-type 12-12-12 fertilizers with phosphorus solubilities in water ranging from about 2 to 60% of the total phosphorus, calcium metaphosphate, monoammonium phosphate, and a liquid 9-9-9 mixture were applied to Evesboro loamy sand and Davidson silty clay loam. The fertilizers were applied 4, 2 and 1 month prior to planting, respectively, and on the date of planting to determine the influence of water-solubility, soil type, and time of fertilizer application prior to planting. The first crop of Starr millet indicated a superiority of the highly water-soluble phosphates on both soils irrespective of the time of application. Whereas time of fertilization made little, if any, difference at the first harvest on the Evesboro soil (low-phosphate fixing capacity), preplanting applications of the more soluble phosphates definitely reduced their effectiveness on the Davidson soil (high-phosphate fixing capacity). The second cutting showed the same trends with smaller differences. The third showed very small differences between the fertilizers on the Davidson soil, but significant differences persisted on the Evesboro soil. Post-fertilization seeding gave only small differences at the third harvest on either soil.
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