Simple empirical intensity and buffering capacity measurements to predict potassium uptake by white clover

Potassium in the soils of New Zealand—A review

“…The K-supplying power of New Zealand's soils has been assessed using both field During & Campkin 1980) and pot culture experiments (Haylock 1956;Campkin 1972;Lee & Gibson 1974;During & Duganzich 1979;Jackson & During 1979;Jackson 1985;Surapaneni et al 1991). Although the pot culture technique may be useful in characterising and comparing soils for their K-supplying power under standard experimental conditions, field trials are more relevant to crop production.…”

“…Surapaneni et al (1991), however, showed that the nitric acid method was superior to the NaTPB method for yellow-grey earth soils. Alternative methods of measuring the exchangeable and non-exchangeable K-releasing power separately are mainly based on exchange processes in soils e.g., exchange isotherms (Goulding 1983(Goulding , 1986Elkhatib & Hern 1988), quantity and intensity (Q/I) relationships (Beckett 1964;Lee 1973;During & Duganzich 1979;Sparks & Huang 1985;Haby et al 1990;Cervantes & Hanson 1991;Herlihy 1992), electro-ultrafiltration (Nemeth 1982;Sparks 1987;Haby et al 1990;Liu et al 1992;Herlihy 1992), and cation exchange resins (Lee & Gibson 1974;Talibudeen et al 1978;Martin & Sparks 1985). These methods are not used in New Zealand and, according to Sparks (1987), are of little practical value for predicting K-releasing power.…”

Advances in Soil Science

“…Thus, During and Duganzich (1979) obtained highly significant correlations (r 2 = 0.9) for the K uptake of white clover grown on eight soils widely differing in cation exchange capacity when K+ concentration and K+ buffer power of soils were taken into consideration.…”

“…It is supposed to be an important indicator of K+ availability. Results obtained until now, however, do not support this concept (Wild et a1., 1969;During and Duganzich, 1979). Nair and Grimme (1979), growing oats (Avena sativa) on four different soils, found only a weak correlation between the ARo data and the K+ uptake of oats while the correlation with the EUF data was satisfactory (r2 = 0.77).…”

“…Both the saturation extract method and the EUF technique provide data that are more closely related to the K+ concentration of the soil solution which, as outlined above, is an important factor of K availability. It may be for this reason that frequently the K+ concentration of the soil solution corresponds better with the K+ uptake of crops than the exchangeable K+ (von Braunschweig and Mengel, 1972;During and Duganzich, 1979). In addition, the EUFextractable K+ was a better indicator of K+ availability than the exchangeable K + in field studies with flooded rice (Wanasuria et a1., 1981).…”