ANPR350/450 – Sheep Management ____________________________________________ 4-1 ©2009 The Australian Wool Education Trust licensee for educational activities University of New England 4. Pasture and Grazing Management J. Scott, J. Pratley, J. Virgona Ed. D. Cottle Learning objectives On completion of this topic you should be able to: • outline the key principles behind pasture establishment and grazing management of pastures • demonstrate a thorough understanding of grazing management concepts and the science behind grazing management principles • evaluate the economics of weed control • discuss relevant literature relating to grazing management and sustainability • access and utilise recent research and extension efforts describing sustainable grazing systems and recognise the difference between anecdotal claims and objective evidence • Understand some of the important differences in the capacity of different pasture species to support sustainable wool production and the important influences of fertiliser, stocking rate and grazing management Key terms and concepts Pasture establishment; Grazing management terminology (especially continuous, rotational and tactical grazing); Spatial and temporal changes in grazing behaviour and pasture supply; Sustainability; 3-leaf and 4-leaf stage of plant growth; Grazing tolerance; Light interception and pasture growth; Selective grazing; Stocking rate and its interactions with fertiliser and pasture utilisation; Herbage intake; PROGRAZE, herbage mass and digestibility; Rest period; Remote sensing of herbage; Nutrient responses; Animal production per head and per hectare 4.1 Introduction A successful grazing enterprise provides high levels of animal performance but its ongoing success or sustainability depends also on the maintenance of high quality pasture. Emphasis therefore needs to be placed on ensuring good establishment of desired pasture species and ongoing management of the pasture to minimise deterioration of plant populations. The establishment process is very expensive and it is sound economics to maintain the pasture in a productive condition for as long as possible to spread the establishment costs over more years. It follows that pasture species and varieties need to be well adapted to their environment. Local knowledge and research outcomes are vital sources of information as to what is best suited to a particular environment, soil type and proposed enterprise. Pastures are by far the cheapest form of nutrition for grazing ruminants, as they can produce one tonne of feed for as little as $10 to $30 per tonne (dry matter) per year. When one contrasts this with prices for hay of $180 per tonne through to grain of up to $500 per tonne (and more during drought) it is easy to see the relative costs of pasture being much lower than purchasing grain for supplementary feeding for example. Even with irrigated pastures for dairy production, the cost per tonne of the grain may rise but rarely above $60 per tonne of dry matter produced. Of course, the nutritional value of 1 tonne of pasture is usually lower than that of grain but the difference may be only 30%, which is much less than the price differential. There are greater public expectations of graziers than has been the case in earlier times. The ongoing pressure of raising productivity to maintain profitability is ever present, whilst at the same time the community expects the natural resource base to be protected from degradation and biodiversity to be enhanced (Kemp and Michalk, 2007). There are the environmental challenges of