Residual Effect of Large Applications of Phosphorus on High Phosphorus Fixing Soils
1967
Kamprath, E. J.
Large initial applications of P to high P-fixing soils had a marked residual effect on the yield of corn (Zea mays L.) 7 to 9 years after application. On a Georgeville soil very low in available phosphorus, an initial application of 612 pounds of P per acre 9 years earlier was still supplying sufficient P for high corn yields. Response of corn to 22 pounds of P per acre applied in a band was significantly affected by the P applied 8 and 9 years earfief. Similar results were found with the P uptake by corn grain. Above 8 ppm of available soil P (0.05N HC1 + 0.025N H²SO⁴, extractant), there was no further increase in corn yields. For high corn yields on high P fixing soils, the entire root zone rather than isolated bands should have a high level of P.
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