Effect of leaching on soil properties and lucerne growth following lime and gypsum amendments to a soil with an acid subsoil

摘要

Amelioration of subsoil acidity was studied in pots containing reconstructed profiles. Gypsum or lime was placed in the A or B horizon, either with or without leaching, before growing lucerne. Liming'the A horizon did not alter the pH, exchangeable Al3, Al3+:Ca2+ratio, or root yield in the B horizon. The high lime application rate gave a pH of 7.8 in the A horizon. Lime addition to the B horizon increased pH, decreased Al3+and Al3+: Ca2+; and increased root growth in that layer. Although gypsum increased exchangeable Ca2+the pH was decreased, and Al3+:Ca2+only decreased slightly in the B horizon. Gypsum did not increase B horizon root yields, with or without leaching. The practical implications of these results are discussed.