Sustainability of New Zealand high‐country pastures under contrasting development inputs. 1. Site, and shoot nutrients

Abstract

Two adjacent studies of sheep-grazed mixed-species pasture, on a Pukaki/Tekapo high country soil, have been on-going since 1982. One compared 30 combinations of 5 increasing growth regimes (0-500 kg ha -1 yr -1 superphosphate +irrigation) × 3 stocking rates × 2 stocking methods; the other compared 27 combinations of P and S fertiliser (0-100 kg ha -1 yr -1 ). Summer shoot concentrations of P, S, N, and other macro-and micro-nutrients in Lupinus polyphyllus, Trifolium ambiguum, T. hybridum, T. repens, T. pratense, Hieracium pilosella, Festuca rubra, and Dactylis glomerata are reported for the PxS study. Dactylis glomerata was notable for its large change in shoot P and S concentration with changes in P and S soil levels, whereas Lupinus polyphyllus and Festuca rubra showed low variation in S shoot concentration, and Hieracium pilosella low variation in shoot P concentration, under varying fertilisers rates and combinations. Species tended to have their highest shoot S concentration where they made their major contribution in mixed swards. Herbage Se, I, and Na levels were low to deficient for sheep nutrition.

Sustainability of New Zealand high‐country pastures under contrasting development inputs. 2. Soil inorganic components

“…The discussion of soil inorganic components needs to take cognisance of the response of a range of other factors investigated in the trials, some of which are given in Scott (1999), and others which will described elsewhere. Features include rapid changes in relative abundance of species according to the different treatments imposed, root distribution to 40 cm, the increase of productivity as measured by sheep grazing capacity with increasing fertiliser level, with this increase being largely determined by S fertiliser levels, the treatment effects being slightly greater on soil organic components than inorganic components, and the effect of different grazing managements being relatively slight.…”

“…Annual variations in the actual analysis of P and S contents of the superphosphate were taken into account. The actual mean annual fertiliser rate over the 10-year period as applied S and P are given in Scott (1999, fig. 4) for the PxS trial.…”

“…43 Full details of the site and management regimes were given by Scott (1999). The two trials were adjacent to each other at the AgResearch Mt John trial site near Lake Tekapo and were established by partial over-drilling of Hieracium-infested fescue tussock grasslands in 1982 with a mixture of 25 legume and grass species (Scott 1998).…”

Sustainability of New Zealand high‐country pastures under contrasting development inputs. 6. Fertiliser efficiency

“…Previous papers have described the trial designs and fertiliser levels used (Scott 1999), the changes in soil inorganic components after 10 years (Scott 2000a), sheep carrying capacities over 15 years (Scott 2000b), and organic components including pasture response (Scott 2000c). These could be considered as referring to a maintenance phase after an approximately five-year initial pasture development phase.…”

“…These interests have been particularly true for South Island high-country rangeland pastoral farming. The present series of papers attempts to quantify some of these production and sustainability aspects based on two long-running grazing pasture trials under contrasting management inputs of fertiliser and grazing management (Scott 1999(Scott , 2000a(Scott , 2000b(Scott , 2000c(Scott , 2000d.…”