The relative strengths of phosphate fertiliser application and white clover cultivar introduction for hill pasture improvement

Combinations of four phosphorus (P) fertiliser rates (0, 8.5, 22.5 or 26.5 kg/ha per year of citrate-soluble P) and three pasture type types with different white clover germplasm, ‘resident’ cv. ‘Huia’ and cv. ‘Tahora’ were compared in self-contained, replicated farmlets grazed by sheep over four years. Fertiliser increased white clover herbage accumulation (HA) 3- to 4-fold compared with the control treatment, and increased total sward HA by 50%. Introduction of Tahora white clover significantly increased white clover and total sward HA and nitrogen fixation compared with the resident and Huia-sown swards. Sheep liveweight gain was significantly greater in all systems fertilised with P (438 versus 243 kg/ha for the unfertilised control) and in systems sown with Tahora (425 versus 372 kg/ha for resident and Huia).