The effect of internal parasites on the performance of lambs grazing different forage species was examined in two experiments.

The sustainability of using irrigation to produce food depends not only on the availability of sufficient water, but also on the soil's 'response' to irrigation. Stocks of carbon (C) and nitrogen (N) are key components of soil organic matter (SOM), which is important for sustainable agricultural production. While there is some information about the effects of irrigation on soil C stocks in cropping systems, there is a paucity of such studies in pastoral food production systems. For this study, we sampled soils from 34 paired, irrigated and unirrigated pasture sites across New Zealand (NZ) and analysed these for total C and N. On average, irrigated pastures had significantly (P < 0.05) less soil carbon (C) and nitrogen (N) than adjacent unirrigated pastures, with differences of 6.99 t C ha and 0.58 t N ha in the uppermost 0.3 m. Differences in C and N tended to occur throughout the soil profile, so the cumulative differences increased with depth, and the proportion of the soil C lost from deeper horizons was large. There were no relationships between differences in soil C and N stocks and the length of time under irrigation. This study suggests SOM will decrease when pastures under a temperate climate are irrigated. On this basis, increasing the area of temperate pasture land under irrigation would result in more CO in the atmosphere and may directly and indirectly increase N leaching to groundwater. Given the large and increasing area of land being irrigated both in NZ and on a global scale, there is an urgent need to determine whether the results found in this study are also applicable in other regions and under different land management systems (e.g. arable).

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To determine the best method of pasture establishment on non-cultivable hill country (>20o slope), four treatments were compared in one year on north and south aspects at four sites with contrasting climates and soil types. Sites were located in Waikato (1), Hawke's Bay (2) and Canterbury (1). The treatments included seed mix (grasses, legumes and herbs (GLH); legumes only (LEG)) and sowing time (spring; autumn). Six weeks after sowing, seedling establishment, as a percentage of viable seeds sown, was: i) greater on south than north aspects for perennial ryegrass (31% vs 18%) and birdsfoot trefoil (5% vs 4%); ii) greater for total sown species (14% vs 8%), subterranean clover (7% vs 4%) and red clover (25% vs 14%) in the GLH than LEG mix, but greater for white clover in the LEG than GLH mix (17% vs 8%); iii) greater in autumn than spring for perennial ryegrass (36% vs 13%) and total sown grasses (22% vs 9%) but greater in spring than autumn for lotus (6% vs 3%). Plantain established well in spring in summer-wet environments, while in summer-dry environments establishment was greater in autumn. Broadcasting seed on south aspects during autumn is likely to result in the highest establishment of sown grasses and legumes, but not necessarily of herbs. The trials were conducted in an unusually wet season. Repeating a subset of the treatments at these sites will provide a greater understanding of responses to climatic variation. Keywords: pasture renewal; pasture establishment; pasture mixtures; oversowing.