Studies on Establishment of Italian Ryegrass-Rhodes Grass Pasture by Sod-sowing Method : 1. An Evaluation of Sod-sowing of Italian Ryegrass to Rhodes Grass, Orchardgrass, Ladino Clover and Alfalfa Pastures

1. In order to save labor in annual forage crop cultivation and to establish high producing grassland which will make year-round utilization possible by introducing annual forage crop, field tests were conducted to introduce Italian ryegrass by sod-sowing method to pastures of Rhodes grass, orchardgrass, Ladino clover and alfalfa on volcanic ash soil of the Central Experiment Station from 1963 through 1965. 2. Total dry matter yield of thus sod-sown Italian ryegrass was 90-120kg/a and the amount had not much difference to that of customary method (by plowing under former crop and single sowing of the ryegrass), whenever regrowth of the former existing crop had been poor. But when the regrowth had been rich, dry matter yield of the ryegrass was 70-90kg/a, showing 20-30% decrease to that of the customary method. 3. Sum total of yearly dry matter yields of existing Rhodes grass and introduced Italian ryegrass sod-sown was 140-190kg/a, and the amount was much higher than that of the existing perennial crop only. 4. Sod-sowing of Italian ryegrass took less labor than the customary method and this fact together with the higher yield than that of the perennial crop only made the sod-sowing method more promising. 5. It is necessary, however, in making successive cultivation possible by sod-sowing of Italian ryegrass to Rhodes grass pasture to examine following points : i) to improve germination and secure stable grass stand of Italian ryegrass sod-sown to Rhodes grass pasture, ii) to control competition between existing Rhodes grass and sod-sown Italian ryegrass in early growth stage of the latter and iii) to establish the best method of fertilizer application in sod-sowing.