There are limitations to the production and persistence of white clover in drought prone regions. We report on the population dynamics of white clover during the summer/autumn drought of 2000. Seventeen paddocks were selected from Marlborough, Mid Canterbury, South Canterbury and North Otago on the east coast of the South Island, and Wairarapa in the North Island. The pastures were sown in 1998/99 and are comprised of ryegrass, tall fescue, cocksfoot or combinations of these as the grass base, with white clover included in the mix. White clover populations were monitored pre- and post-drought using tiller cores. The percentage of each region's long-term mean rainfall received during the 6-month "drought period" had the largest influence on the presence of white clover in these pastures. Marlborough, with only 73 mm of rainfall during November 2000-April 2001 (23% of its expected rainfall) suffered a 95% reduction in white clover. Mid Canterbury, South Canterbury and North Otago, at 53-61% of expected rainfall had a 40-78% loss. In contrast, Wairarapa, with 303 mm of rainfall, lost only 8%. The rate of recovery was closely related to the magnitude of white clover loss during drought. In regions where large losses occurred, further sampling after 18 months showed little increase in white clover presence. Key words: drought, persistence, populations, seedling, Trifolium repens, white clover

How do we know which pastures to renew and do we increase profitability when we renew them? An inventory of pasture production of the Telford dairy farm was developed using paddock grazing records to estimate potential pasture production and variability from different soil types. Using the difference between low and high producing pastures as the potential for improvement, the change in pasture production with renewal was calculated and valued using several methods, from the simple conversion of extra dry matter into milk solids production through to whole farm systems optimisation using Farmax Dairy Pro. The cost of pasture renewal was highest when valued by the Pasture Renewal Charitable Trust model when the cost of lost grazing was estimated. The return for pasture renewal was lowest from Farmax Dairy Pro modelling when whole farm-integration was considered. At the average value of milk for the last 5 years, the payback period was between 2.5 and 3.1 years, depending on the model used. Keywords: analysis, modelling, pasture production records, pasture renewal, soil types.

Recent developments in cereal breeding for forage production have given the potential to greatly increase annual forage dry matter (DM) production. This paper reports on the findings from two cereal forage production trials on irrigated Canterbury land. Trial 1 studied the potential of a range of single and multi-grazed cereal forages over a 9 month period to produce high yields and quality from both grazing and whole-crop silage forage. Trial 2 studied the suitability of different cereal/ legume combinations for green-chop silage grown over a three month summer period. These two cereal forage systems, when combined in a 12 month period, produced in excess of 25 tonnes of high quality forage per hectare, almost double the DM production achieved using current perennial pasture based systems. Trial 1 showed no significant difference in the total DM produced by either single or multi-graze treatments. In Trial 2 pea/cereal combinations produced over 6 t DM/ha. Due to an earlier final harvest the multi-graze system is more easily combined with the summer crop and more likely to produce a lower cost and more sustainable forage system. Animal performance on forage produced in Trial 1 showed that dairy calves can grow well on cereal forages during winter. Keywords: cereal, feed supplements, forage, forage yield, legume, silage

Potassium (K) build up in soils is a side effect of prolonged farm dairy effluent irrigation, and can result in animal health issues. A kale crop was planted to investigate its potential to take up K applied in farm dairy effluent.

This paper describes the development of a forage selection decision tool. The project was carried out in conjunction with Meat and Wool New Zealand and farmer mentor groups in Manawatu, Canterbury and Southland. The model uses a multi-criteria technique called Electre III which helps rank the characteristics of forages relative to environmental conditions and farmers objectives. The approach allows farmers to rank and compare suitable species and cultivars. The decision tool provides advice on appropriate seed mixes and specific information on establishment and management. In addition the model was structured to allow farmers to discover limitations to their environment or management systems through a process called 'back-chaining'. An example of this is where a farmer queries the model to discover what conditions prevented a forage from being selected. Demonstrations of the Forage Master to a range of farmer groups nationwide has provided excellent feedback on the value of the decision tool, firstly for aiding on-farm decision making and secondly, benefits associated with the information provided in the help links. Keywords: computer model, cultivars, forage, forage selection, multiple criteria, pasture species