Manganese deficiency in subterranean clover (Trifolium subterraneum L.)

Abstract

Manganese deficiency of subterranean clover (Trifolium subterraneum L.) appeared in pots of a Kangaroo Island soil, the pH of which had been changed by the addition of small amounts of lime from 6.2 (the natural pH) to 6.3-6.5. As a result of this deficiency, yields were severely depressed. The symptoms of manganese deficiency in subterranean clover are described. Chemical analyses of healthy plants showed manganese contents, expressed on a dry matter basis, varying from 30 p.p.m. on a slightly acid soil to over 300 p.p.m. on a strongly acid soil. Plants in various stages of manganese deficiency showed only 4-25 p.p.m. It is suggested that, at the flowering stage, 25 parts of manganese per million parts of dry matter represents the minimum amount of manganese for healthy growth of subterranean clover. Applications of manganese sulphate to the soil at a rate of 56 lb/acre prevented the appearance of manganese deficiency symptoms, increased the manganese content of the clover to 35 p.p.m., and led to nearly a 20-fold increase in growth. Manganese deficiency in subterranean clover has also been seen in the field on Kangaroo Island and one sample examined showed only 9.4 p.p.m. of manganese on a dry matter basis.