In the Starborough-Flaxbourne area the local farming community, alarmed at the increasing hill slope erosion, set up a soil conservation group. Accelerated erosion was a symptom of the past 12 years of below average rainfall. Removal of vegetative cover by livestock had enabled wind to erode areas of the thin topsoil exposing vulnerable sodic subsoil to rill and tunnel erosion. This highlighted the need for farms to adapt their livestock systems to a drier environment if they were to survive. Keywords: adaptation, conservation, decision making, drought, erosion, lucerne, Medicago sativa

Decision support models have been developed to assist management in dairy systems. This paper describes Farmax Dairy Pro (a pastoral grazing model of a dairy farm) and presents an evaluation of it using two independent farmlet studies carried out in Hamilton and Palmerston North, New Zealand with spring-calving dairy cows. Farmax Dairy Pro predicted, to a high degree of accuracy, mean annual yields (per cow and per hectare) for milk, fat, protein and milksolids (MS; fat'protein) and mean annual concentrations of MS. Monthly predictions were predicted with less accuracy than whole lactation values, but still with moderate degrees of accuracy compared with other comparable models. The general trajectory over time of yield and MS concentration was predicted well for all datasets, but in some instances the model over or under predicted the degree of variation between months. The trajectory of body condition score over time was reliably simulated in early lactation but with some discrepancies in late lactation. The model was then used to determine if it was possible to achieve 1750 kg MS/cow per ha using forages grown within the milking area for the Hamilton study. Managerial changes represented in the model, which included earlier calving dates, use of a chicory crop and additional intakes of pasture in summer, predicted increases in performance of 50Á190 kg MS/ha, still at least 81 kg MS/ha short of the target level of production. Farmax Dairy Pro can be used to predict animal, farm and financial performance for different management scenarios.

Farm systems in the dry sub-humid region of the Upper Waitaki predominantly graze merino ewes on extensive oversown and topdressed hill and high country. Smaller areas of flatter land are used to conserve winter forage crops, and grow supplementary feed and high quality pastures. The slow growth rate of merino lambs means they are traditionally retained on these improved pastures to finish in the following spring. In this system livestock demand peaks in the driest month of January and continues to be high through winter. Bog Roy is a farm that has changed this system and has established 200 ha of lucerne with the goal of fully feeding ewes during lactation. Pre-weaning lamb growth rate has increased from 205 to 235 g/head/day, opening the opportunity to sell heavier lambs in early January. Ewe lamb replacements are reaching heavier pre-winter live weights (38 kg versus 35 kg) and the flow-on effect is higher two-tooth scanning (129% versus 111%) and weaning (100% versus 84%). Lucerne has also improved the feeding of mixed age ewes from lambing to weaning, and lamb mortality has reduced from 30% to 21%, increasing weaning from 115% to 130%. The store production system also means livestock demand is kept low during the dry period and remains low through winter. Conserved feed is now only required for 50 days compared with 100 days in the traditional system. This has reduced supplementary feed costs from $10.33/stock unit (SU) to $4.82/SU. Shifting ewes to rotationally graze lucerne in large mobs early in the growing season has decreased the stocking rate on hill country. This has allowed cover to build during each spring with promising responses from legume species.

Soil nutrients in topsoils (O-7.5 cm) on grazed hilly and steep land on 2 high country sheep farms with contrasting climate in the upper Waitaki district, South Island, New Zealand, were compared before and after a 14-15 year period. In addition, effects on soils of 2 farm management systems were compared by sampling similar soils on adjacent farms.

Pasture renewal is an important strategy for farmers to improve the yield of home-grown forage. This paper quantifies long-term national and regional trends in regrassing within the dairy sector and links these patterns to suggested major drivers, using simple regression analysis. Dairy farm financial data relevant to regrassing expenditure were sourced from annual dairy sector economic reports and DairyBase, while regional potential evapotranspiration deficit data were sourced from climate records and cropping data from a recent MPI report. Real and relative expenditure on regrassing has increased over this period, and appears to be positively associated with both cropping activity and drought severity, particularly in some North Island regions. The emergent picture is one of a complex of interacting drivers (climate, production, prices, forage products, soils and time) which fuel a vicious cycle of poor persistence and resowing. This situation draws attention to the need for solutions to protect regrassing investments.