RESIDUAL EFFECTS OF PHOSPHORUS IN SOIL AT DIFFERENT pH LEVELS AS MEASURED BY YIELD AND PHOSPHORUS UPTAKE BY OATS

Publisher Website
Google Scholar
Abstract
The residual effect of P applied 8 yrs. previously was measured by first sampling yield responses, increased P content of oats at 3 samplings, and a decrease in the P % from the fertilizer containing radio-P at 3 sampling periods. Oat yields were increased by an appln. of 11 lb. of P in 1949, demonstrating that the residual P, even at the highest level of P appln. in 1941, was insufficient for max. yields. The response to additional P was to be expected, however, on the basis of results from rapid microchemical soil tests, which indicated a low level of available P. The residual available P was measurable by Peech''s rapid microchemical soil test as well as by Bray''s ammonium fluoride method, with a good correlation between the 2 methods. Variability of the radiochemical analysis between replicates emphasized the nonuniformity of P distr. when applied to the soil under field conditions.
Keywords