Responses of subterranean clover and Italian ryegrass to application of lime

A glasshouse experiment evaluated dried herbage yield responses of dense swards of subterranean clover (Trifolium subterraneum cv. Trikkala) or Italian ryegrass (Lolium multiflorum cv. Aristocrat) to applications of different amounts of lime (0, 2.5, 5.0, 7.5, 10 and 12.5 t lime/ha) to either a loam or a sand. Yields were measured at 4 harvests [29, 51, 86 and 108 days after sowing (DAS)] when ryegrass plants had 3 leaves per tiller. Increasing amounts of lime raised the pH (1:5, soil: 0.01 mol CaCl(2)/L) of the loam by 2.7 units and that of the sand by 2.0 units. Applications of lime significantly (P<0.05) increased dry herbage yields, by between 16 and 53%, for: (i) clover on the loam soil at 86 and 108 DAS, and for the sand at 108 DAS; (ii) ryegrass on the loam at 51, 86 and 108 DAS, and on the sand at 108 DAS. Increasing amounts of lime had no effect on the concentration of nutrient elements in dried herbage of either clover or ryegrass, except that the concentration of calcium increased, and the concentration of sodium, manganese and zinc (and boron for ryegrass only) all decreased. Additions of lime had no effect on dry matter digestibility, metabolisable energy, concentration of crude protein or water-soluble carbohydrates in dried herbage at any of the 4 harvests.