Sustainability of New Zealand high‐country pastures under contrasting development inputs. 3. Sheep carrying capacity

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

“…The maximum m the response was most marked for the mean 15-year grazing data, which included the early development stages of the pastures. As reported earlier (Scott 2000b), the carrying capacities increased over time in relation to S fertiliser rates, so that the maximum in the Sresponse function was less marked in the function derived from estimation of asymptotic carrying capacities under different fertiliser combinations (Fig. 1).…”

“…The empirical data on the relationship between sheep carrying capacity over 15 years and 31 different annual S and P fertiliser rates were reported in Scott (2000b) for the combined treatments of two grazing trials. In summary, both trials were adjacent at the AgResearch Mt John trial site, Lake Tekapo, and were run simultaneously with treatments in common.…”

“…The first used the mean carrying capacity of each treatment over the period of the trials and, thus, includes the initial development phase. From the data it was also possible to estimate the asymptotic carrying capacity of each treatment from regression between the inverse of years from start of development and carrying capacity in each year, under the assumption of continuation of the same fertiliser regimes (Scott 2000b). These asymptotic estimates were used to derive a second response function.…”

“…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.…”