Availability of boron and phosphorus as affected by liming an acid potato soil. [Zea mays L. ; Medicago sativa L]
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An Entic Haplorthod, cropped for many years to potatoes, was used for plant pot and chemical studies involving the effects of pH increases by liming on the availability of B and P to Zea mays L. and Medicago sativa L. Increasing amounts of B added to the soil increased yields and B contents of alfalfa but caused increased toxicity symptoms in corn. Boron toxicity in corn was prevented by pH values above 6. When only the standard rate of P was applied, best growth of both crops was in soil at pH values from 5 to 5.7. When pH values were above 6, growth was retarded by deficiency of P. At pH values above 6, the addition of the high rate of P practically doubled dry-weight yields of corn and produced more than 20-fold increases in alfalfa yields. Deficiency of P induced by liming decreased with time. Parallel behavior of B and P in this study supports the hypothesis that both elements may be bound in podzolized soils by similar pH-dependent mechanisms, probably precipitation or adsorption by hydroxy Al. 14 references, 3 figures, 3 tables.