Effects of fertiliser potassium : sodium ratio on yield and concentration of sodium, potassium, and magnesium in lucerne and white clover

Abstract

The effects of various K:Na fertiliser ratios on the uptake of Na, K, and Mg by lucerne (Medicago sativa L. cv. ‘Wairau’) and white clover (Trifolium repens L., cv. ‘New Zealand Certified’) were evaluated using two soils, in a glasshouse experiment. Herbage Na concentrations tended to increase with increasing proportion of Na in the fertiliser mixture, but the magnitude of the effect was greater for white clover than for lucerne. The effects of K fertiliser addition on Na uptake appeared to be more complicated than a simple ion antagonism, as indicated by the varying results for the two plant species on the two soil types. K fertilisers depressed Mg uptake more than did Na fertilisers. The practical implications of the findings are discussed.