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Agronomy Journal Abstract -

Indexes of Availability of K, Mg, Ca, and P in Connecticut Soils1


This article in AJ

  1. Vol. 61 No. 2, p. 330-331
    Received: Apr 16, 1968

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  1. D. E. Peaslee2



Uptake of K, Ca, Mg, and P by tomatoes grown in the greenhouse was the basis of plant indexes of availability of these nutrients in six soils from Northeastern U.S. Parent materials included acid tills from schist and gneiss, basic tills from limestone, lacustrine deposits, and alluvium. Initial pH values ranged from 4.8 to 6.9. Chemical indexes of available nutrients were established using three extractants: 0.73 N NaOAc + 0.53 N HOAc; cation + anion exchange resins; and 0.025 N HCl + 0.03 N NH4F. Plant indexes were highly correlated with chemical indexes for K, Mg, and Ca (r = 0.94 to 0.99) but were not correlated for P (r = 0.35 to 0.47). Multiple linear regression was used to relate plant indexes for P to inorganic P extractable in 0.73 N NaOAc + 0.53 N HOAc and total organic P (R = 0.89). These results indicate that extractants or extracting conditions that reflect contents of mineralizable organic P in such soils should markedly improve correlations between plant and chemical indexes of P.

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