Phosphorus nutrition of plants influenced by manganese and aluminum uptake from an oxisol
1978
JONES, J PRESTON | FOX, L.
The objectives of this study were to evaluate the effect of changes in soil pH on the plant availability of soil phosphorus and the interaction between Mn and Al accumulation and P response of tomato and corn plants.Yield response of tomato plants grown in pots to the level of P in soils was affected by soil pH. Plants in soils with pH values of 6.3, 6.7, or 7.2 produced maximum growth if the soil solution P level had been adjusted to 0.2 ppm. At lower soil pH values, 5.1, 5.3, and 5.7, yield increased up to 0.8 ppm, the highest solution P level employed; this yield, nevertheless, was still below that for higher pH values. By contrast, the effect of P fertilizer on corn hardly varied at different pH levels.Evidence of Mn and/or Al toxicity on tomatoes is presented. Apparent toxicity was lessened by high levels of P. A threshold toxicity level of 450 ppm Mn in tomato tops is proposed.Soil P solubility as measured by phosphate sorption isotherms did not change over a range of soil pH between 5.1 and 7.2.
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