Effects of liming on soil pH and manganese toxicity in a Goulburn valley pear orchard

Abstract

The effects of low soil pH and its correction by liming on the performance of Josephine de Malines and Packham's Triumph pear trees, under irrigation conditions, in the Goulburn Valley were studied for 14 years. Under low soil pH conditions, Mn, Fe, and Al became more available in the soil, but the only element to be found in toxic quantities in plant tissues was Mn. Under these acid conditions, Josephine de Malines pears grew and yielded poorly and exhibited Mn toxicity symptoms in the form of internal bark necrosis and coarse fruit skin russet. Packham's Triumph pear trees were not affected adversely by acid soil conditions. When low soil pH was corrected to the desired level by lime applications, the Mn became less available in soil, its concentration in the plant tissue was reduced, and Mn toxicity symptoms largely disappeared.