SPECIES, AND FERTILISER EFFICIENCY - A HIGH COUNTRY EXAMPLE

Abstract

Species dominance and sheep grazing days relative to fertiliser costs are given for the first 6 years of 2 trials at Lake Tekapo. Both were sown in a multiple species mixture. Trial I examined 27 different annual P and S levels; Trial II examined 30 combinations of 5 superphosphate levels, 3 sheep grazing intensities and 2 stocking methods. Pastures were mostly legume dominant, and species differences were related to P fertiliser and stocking method. Perennial (Russell) lupin (Lupinus poflyphyllus) dominated at all low to medium fertiliser rates, alsike clover (Trifolium hybridum) at intermediate rates, and cocksfoot (Dactylis glomerata) and white clover (T repens) at high ferttliser rates. The stocking rate achieved was related to both S and P rates. Greatest fertiliser efficiency (returns v. costs) was at low annual rates of 4-5 kg P plus 16-25 kg S/ha. Keywords: lupin, cost-benefit, cocksfoot, alsike clover, phosphate, sulphur, sheep grazing management, fertiltser efficiency.