BARLEY SEEDLING GROWTH IN SOILS AMENDED WITH FLY ASH OR AGRICULTURAL LIME FOLLOWED BY ACIDIFICATION.

Calcium-rich coal combustion fly ash can be used as an amendment to neutralize soil acidity because of its oxides and carbonate content, but its aluminum content could inhibit plant growth if soil pH values fall below optimal agronomic levels. This study measured root and shoot growth of an acid-sensitive barley (Hordeum vulgare L. ʹKearneyʹ) grown in the greenhouse on three naturally acid soils. The soils were either untreated or amended with various liming materials (dry fly ash, wet fly ash, and agricultural lime) at application rates of 0,.5, 1, and 1.5 times the recommended lime requirement, then treated with dilute acid solutions to simulate management-induced acidification. Plant growth indexes were measured at 30 days after planting. Root mass per plant and root length per plant were greater for the limed treatments than in the acidified check (0.0 x rate). Root growth in the limed treatments did not differ from root growth in the original nonacidified soils. Top mass per plant in all limed soils was either larger than or not different from that in the original nonacidified soils. Based on top mass per plant, no liming material or application rate was clearly superior. Both fly ash and agricultural lime reduced the impact of subsequent acidification on young barley plants. Detrimental effects of aluminum release on plant growth were not observed. Calcium-rich fly ash at agronomic rates is an acceptable acid-neutralizing material with no apparent negative effects.