Comparison of potassium chloride, bicarbonate, and metaphosphate, and calcined orthoclase, as sources of potassium for white clover

Abstract

KCl, KHC03, KP03, and a calcined potash feldspar, were compared as sources of K in a pot experiment with a K-deficient yellowbrown loam, a soil from andesitic volcanic ash (the New Plymouth black loam), using white clover as the test crop. KHC03 and KP03 gave responses similar, in terms of dry matter yield and K content of the clover, to those given by KCl, and uptake of K was just as rapid. Calcined feldspar gave only a very slight response.

Potassium metaphosphate as a fertiliser for pastures

“…Edinburgh) with Although a number of investigators (e.g. Metson and Saunders 1962;Harris 1963;De Ment. Terman.…”

A comparison of slow release potassium fertilisers for pasture

“…Potassium chloride has disadvantages as a fertiliser for grazed pasture. Not only is the potassium (K) susceptible to leaching on free-draining soils (Hogg & Cooper 1964;Hogg & Toxopeus 1970), but, following topdressing, there is rapid luxury uptake of K by pasture species (McNaught 1958;Saunders & Metson 1959;Metson & Saunders 1962). On K responsive sites, at normal rates of topdressing with KCl, the concentration of K in dry matter (DM) may rise into the range 3.…”

“…Metson & Saunders (1962) experimented with two slightly soluble K compounds, potassium bicarbonate (KBC) and potassium metaphosphate (KMP), and a calcined feldspar (orthoclase) as a means of reducing luxury uptake. The K from KBC and KMP were taken up by the pasture species as quickly as K from KCl; the K of the mica, although it became more soluble in water after ignition, was not readily available.…”