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Critical potassium potentials for crops: 2. Potentials for wheat, maize, peas, beans and sugar beet in their early growth on a sandy loam
Author(s) -
PAGE M. B.,
TALIBUDEEN O.
Publication year - 1982
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1982.tb01806.x
Subject(s) - loam , sugar beet , agronomy , potassium , crop , sugar , yield (engineering) , germination , chemistry , soil water , biology , food science , physics , ecology , organic chemistry , thermodynamics
Summary Wheat, maize, leafless peas, field beans and sugar beet were grown in a constant environment for 4 weeks after germination on a sandy loam containing initially a 70‐fold range of exchangeable K levels. The yield response curves to the mean soil K potential (ΔG K , ca+ Mg) for the growth period for each crop were divided into three linear sections, for positive, zero and negative response, by a numerical iterative method, and from these, exhaustion (Δ G exh ), optimum (ΔG opt ) and toxicity (Δ G tox ) K potentials were derived. Values of ΔG exh were similar for all crops. The Δ G opt values increased in the order legumes < cereals < sugar beet. High potassium potentials which produced decreases in yield were far greater than any likely to be encountered in a natural system. It is suggested that yield reductions at high K potentials were caused by inhibition of the uptake of other cations rather than by toxic levels of K in the plant tissue. At this early growth stage, seed K concentrations and K contents of the crops affected ΔG exh and Δ G opt values in different ways and to different extents. The influence of the K requirements of the crop and the crop's ability to extract K from the soil are briefly discussed.