The log normal distribution is shown to be useful for characterizing cluster distributions produced by coalescence growth mechanisms. The Smoluchowski equation and variations thereof produce cluster size distributions very similar to those produced using nozzle beam expansions and laser chemistry of organometallics. The model provides a statistically unbiased basis for interpreting cluster size distributions produced using a wide variety of synthetic methods. It also provides a unified chemical and physical basis for discussing and rationalizing the results of a wide range of gas phase cluster experiments. Under certain conditions, size distributions can be produced in which there is an alteration in the number of odd and even clusters produced. In addition to some inferences regarding fullerene chemistry, data gleaned from the literature are rationalized on the basis of the kinematics of cluster formation, the fractal dimension of clusters composed of different atoms, the Periodic Table, and the degree to which the translational motion of the coalescing species is diffusional or ballistic.

We show that gas-phase organometallics can be photolyzed using pulsed UV-visible lasers to initiate synthesis of metal clusters. We use the log-normal distribution function to compare this new method of cluster formation to other methods. Cluster size distributions produced using this new method bear a remarkable similarity to those produced using nozzle beam expansion methods. Although there is deviation from this distribution, these growth methods would seem to involve coalescence growth mechanisms as opposed to Ostwald ripening. Possible reasons for the deviation from a log-natural distribution are suggested. Laser chemistry allows synthesis of gas-phase metal clusters because of the very high pressures of metal atoms attainable using multiphoton dissociation of organometallics.

Current winter feeding practice using a daily grazing duration to ration feed is based on the sheep industry of the 1960s to the 1980s when per head performance was much lower than today. This study investigated the impact of changing from a 1-day grazing duration to a 4-day grazing duration during winter on subsequent productivity. Ewe condition score and liveweight, tailing percentages, and tailing and weaning weights of lambs, as well as the incidence of vaginal prolapse in ewes at lambing were recorded over several years on a total of seven farms. Spring pasture growth and botanical composition was measured on one farm. Results suggest 4-day shifting had little impact on vaginal prolapse but did result in more settled sheep, easier winter shifting regime, and less pasture damage, leading to improved pasture production in early spring (P

The Lucerne for Lambs Sustainable Farming Fund project used on-farm data and whole-farm modelling to help farmers understand the impact of increasing the amount of grazing dryland lucerne on Central Otago farms. On-farm results from 2 years showed that spring stocking rate on lucerne-based pasture averaged 10 ewes and their lambs per hectare compared with 3 ewes and their lambs on dryland grass-based pasture. Lamb growth rate was approximately 50 g/day higher on lucerne-based pastures, resulting in a total lamb production of 358 kg liveweight/ha at weaning compared with 108 kg liveweight/ha on grass-based pastures. Whole-farm modelling showed that increased profitability could be achieved by the addition of significant areas of grazing lucerne. Profitability increased by $119/ha on a 5000 ha traditional merino property. Profitability of a 522 ha partially irrigated valley floor property running crossbred ewes was increased by $249/ha. Using lucerne for spring grazing also reduced the impacts of both winter and summer droughts in the variable conditions of Central Otago. Keywords: dryland, lamb growth, lucerne, modelling, profitability, stocking rate, whole farm systems.

Evaluations of Kahu timothy (Phleum prutense L.) included agronomy under mowing (1976-1979) and grazing (1980-1983), and animal performance from grazed pasture (1988-1993) and silage feeding (1989-1991). Agronomic testing showed that Kahu timothy was slow to establish, producing only 28% of the Grasslands Ruanui ryegrass (L.&urn perenne L.) swards in the 6 months after sowing. Frequent, close defoliation severely reduced the yields of timothy and caused losses of plants, reducing longevity. A less frequent defoliation regime with a residual sward height of 30-50 mm gave the greatest sustainable yields. Under mowing Kahu produced significantly less than S51 timothy in summer and winter but under grazing Kahu was superior in spring and summer, resulting in significantly greater annual production. Animal performance testing showed hoggets grazing timothy in spring grew at 218 g/day, significantly greater than the 164 g/day achieved on Grasslands Nui ryegrass. The spring stocking rate on timothy was also significantly greater than on ryegrass, though utilisation of the forage was similar. When fed timothy/red clover silage lambs fed in winter grew at 98 g/day while lambs on standard ryegrass/ cocksfoot/white clover silage averaged a growth rate of only 44 g/day. From the assessment of the physiological state of individual tillers it was observed that timothy had a significantly higher proportion of its tillers with growing points present above ground through late spring and summer than ryegrass. This is suggested as a major reason for the depletion of timothy populations -under close grazing. When grazed correctly in late spring and summer timothy can provide a perennial forage of high feeding value for livestock systems. Keywords: animal performance, Grasslands Kahu, pasture quality, Phleum pratense