The effectiveness of superphosphate top-dressed on established meadows
1950
Stanford, G. | McAuliffe, C. | Bradfield, R.
Studies employing radiophosphorus to determine the extent to which surface-applied superphosphate is utilized by alfalfa, Ladino clover, and orchard grass were conducted on Dunkirk and Mardin silt loam soils in the field. The data obtained from determination of radiophosphorus in the fertilizer and plant and total phosphorus content of these materials reveal that a surprisingly large proportion of the phosphorus in the plants was derived from the fertilizer. Alfalfa utilized surface-applied superphosphate as effectively as did Ladino clover when superphosphate was applied at the rate of 200 pounds per acre, approximately 20% of the phosphorus in the plant having been derived from the fertilizer in each case. With the 1000-pound rate, approximately 50% of the phosphorus in the alfalfa and Ladino plants was derived from the fertilizer, except in one instance where Ladino clove obtained about 60% of its phosphorus from the fertilizer. Several other experiments involving surface-application of granular superphosphate were carried out on Ontario loam in Cayuga County, New York. The average total yield increases due to phosphate range up to approximately 1 1/2 tons per acre. Total increases in yield from application of both phosphate and potash ranged up to approximately 2 1/4 tons per acre. Such yield responses were obtained under conditions of relatively limited rainfall. Some of the factors which seem to warrant consideration in attempting to explain the high utilization of superphosphate which occurred under semi-drought conditions are discussed.
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