Phosphorus Sources and Use in a Cropping Sequence on Silt Loam
1966
Lathwell, D. J. | Musgrave, R. B.
Both the initial and residual effects, of concentrated superphosphate (CSP), calcium metaphosphate (CMP), and fused tricalcium phosphate (FTP) were measured with corn, oats, and alfalfa on the alkaline (pH 7.5) Lima silt loam in two cropping series. The P sources were applied at different times in the cropping sequence during the 10-year period of each cropping series. All three materials proved to be equally satisfactory sources of P both measured by initial crop responses and by residual effects. Rather modest quantities of P were adequate to satisfy the P needs of crops grown on this highly P deficient soil. Based on crop yields, a wide latitude of place of use of P in the cropping sequence was apparent in this experiment as a significant residual effect was observed throughout the experiment. The only restriction on use was that some P applied at the time of making the forage seeding was highly beneficial to subsequent forage yields. Corn responded equally well to residual P as to freshly applied P.
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