Use of pulverised fuel ash from Victorian brown coal as a source of nutrients for a pasture species

Abstract

In a series of Mg solubility tests, pulverized fuel ash (PFA) was a good source of Mg under conditions of acid to neutral pH, and was comparable with established Mg fertilizers when subjected to successive leachings and different shaking times and rates of dilution. A pot experiment, carried out with PFA and three recognized Mg sources at rates equivalent to 0, 20, 60 and 180 kg Mg ha-1, used perennial ryegrass (Lolium perenne cv. Grasslands Ruanui N.Z.) as the indicator plant in a free-draining sand culture. PFA produced a yield response, thought to be due to S, and significantly increased Mg levels in the tissue to > 0.4% on the highest treatment. Sodium levels were elevated (> 1.0% on the highest treatment), and Ca levels were depressed (from 0.9 to 0.6%), on the PFA treatments. Another pot experiment was carried out with PFA at rates equivalent to 0, 500 and 2000 kg ha-1, in the presence and absence of additional solution applied S. At 2000 kg ha-1 PFA (7.3%S) ryegrass yielded 0.95 g/pot, compared with 1.30 g/pot in the presence of additional SO4-S at 24 ppm.