231 Pasture growth and quality on West Coast dairy farms D. E. DALLEY 1 and G. GARDNER 2 1 DairyNZ, PO Box 160, Lincoln University, 7647 2 6 Deemac St. Reefton dawn.dalley@dairynz.co.nz Abstract Variation in rainfall, soil type and growing degree days across the West Coast creates wide variation in pasture growth rates. Farmers require pasture growth rate and quality information local to their environment to assist them with their on-farm decision making. Four farms in different geographical regions of the South Island’s West Coast were monitored for four years to measure pasture growth rate (weekly, plate meter), nutrient composition (fortnightly, pre-grazing) and soil temperature (weekly, 10 cm depth). Average monthly pasture growth rate varied between the farms, however the seasonal trends were similar in all regions. There was signifcant variation in average monthly growth rate between years for individual farms. Soil temperature explained some of the trends in pasture growth rate, particularly in winter and early spring. Pasture quality was lowest during the summer months when neutral detergent fbre concentrations were greater. Pasture crude protein concentration exceeded 25% in 63% of the samples collected. Information reported will allow dairy farmers and their advisors to develop feed budgets and assess the appropriateness of the stocking rate and calving date of the farm relative to the annual pasture growth patterns. Times of year when the greatest variability occurs have now been identifed for each sub-region. Keywords: West Coast, pasture growth, pasture quality, dairy Introduction The West Coast dairy industry, in the South Island of New Zealand, operates in a distinctive environment with its own set of unique challenges. The area has relatively high rainfall and soils which are often poorly drained or may have an impermeable iron pan. The development of “humping and hollowing” and “fipping” practices has improved drainage on some existing farms and expanded the area of land suitable for dairy farming. Despite the West Coast being an important region for milk production, there is a scarcity of basic information on pasture growth and quality for dairy farms in the Buller, Grey and Westland districts (northern, central and southern regions of the West Coast, respectively). Previously reported growth rate information was measured at three sites during the 1970s and 1980s (Radcliffe 1975; Morton & Paterson 1982). Variation in rainfall, soil type and growing degree days across the West Coast has the potential to create a wide variation in soil temperature and pasture growth rates. Morton & Paterson (1982) reported average annual growth rates of 8.1 and 9.4 t DM/ha for Kowhitirangi (Westland) and Ahaura (Grey), respectively. In both regions pasture growth rates peaked during late November, declined in December, remained at a reasonably constant level until the end of March, and then further declined through April and May to a low level from June to September. Despite the West Coast being an important region for milk production, there has been no further monitoring of basic information on pasture growth and quality for dairy farms in the region since the project of Morton & Paterson (1982). Such information is critical for annual feed budgeting, farm system setup (e.g., calving date, stocking rate) and for weekly farm management decisions, especially as dairying expands into new regions. Farmers are looking for new information more local to their environment that will assist them with their decision making. In August 2008 a 4-year project commenced to gather data in a controlled and systematic way from four regions of the South Island’s West Coast. Reliable pasture growth rate information for the regions and data on pasture quality changes will give farmers more confdence in making feeding decisions and help them to evaluate the applicability of research from other regions for their situation. Materials and Methods Rainfall, topography and soil type information were used to identify geographically different regions within the Westland, Grey and Buller districts of New Zealand. The four regions selected were Westport (WEST), Ikamatua (IKAM), Kotuku (KOT) and Kowhitirangi (KOWH). Four monitor farms were selected according to size, location, stocking rate, farming system, record keeping, soil type and willingness of the farmer to be involved and use the information generated. Details of the farms are reported in Table 1. Pasture growth rates were determined by weekly assessment of the pasture height in every paddock on