Poor persistence of sown pastures, trends of low pasture resowing rates and a substantial decline in carrying capacity of non-crop areas bring into question the basis of the philosophy of pasture improvement by sowing pasture species. If graziers are to adopt grazing strategies or stocking rates that are more ecologically sustainable, then clearly they must also be cost-effective in either increasing income or reducing costs so that they are economically sustainable. This paper describes the use of an interactive spreadsheet model developed to assist graziers and their advisers with assessing the long-term profitability of pasture management and/or improvement (and therefore pasture persistence). The model provides a comparative cash flow for different levels of inputs (fertiliser, herbicides and feed supplements) over a 15-year period. Results clearly show that at the same stocking rate, different animal enterprises have markedly different profitabilities over a 15-year period. Further, for native, improved and sown pastures, the most profitable pastures are those that can sustain increased stocking rates for long periods of time, without the need for resowing.
The experiences of participants in the Sustainable Grazing Systems (SGS) Program were examined to understand why more productive and sustainable practices were adopted by producers involved in SGS. This paper explores from a range of perspectives (producers, researchers, extension agents and facilitators) the delivery mechanism that led to these practices being adopted and concludes with a model describing the adoption process observed in SGS. The model describes a continuous 3-stage process of motivation, trialing–exploration and farm practice change. Support for decision making during the transition between each stage of the process was recognised as an essential ingredient for success.
Hyparrhenia hirta (L.) Stapf (Coolatai or Tambookie grass) has invaded roadside areas, travelling stock routes and grazing lands in northern New South Wales and southern Queensland. In these situations it is regarded as an undesirable species. There are no herbicides registered for use on this grass and little information is available on the long-term effectiveness of chemical control. Plots consisted of: 3 treatments imposed before herbicide application (untreated, mown and burnt); 5 herbicides [glyphosate, flupropanate (formerly tetrapion), 2,2-DPA, mixtures of glyphosatel flupropanate, and an untreated control]; 3 application rates for each herbicide; and 2 times of herbicide application (spring 1990 and autumn 1991). Herbicide effectiveness on Coolatai grass was measured by comparing reductions in dry matter and phytotoxicity up to 20 months after application. Six months after the spring application, yields were depressed (P<0.05) by herbicides (flupropanate applied at 4.4 kg a.i./ha and 2,2-DPA at 14.8 kg a.i./ha) and preapplication treatments (burnt plots sprayed with flupropanate at 1.1 and 2.2 kg a.i./ha), but their overall interaction was not significant. Ten months after autumn application, Coolatai grass yields were reduced (P<0.05) by herbicide, pre-application treatment and their interaction. Mowing and burning reduced (P<0.05) yields to 40 % of those in undefoliated plots. Yields were lowest (P<0,05) in mown (flupropanate 4.4 kg a.i./ha) and burnt (glyphosate, 2.16 and 4.32 kg a.i./ha, and flupropanate, 4.4 kg a.i./ha) treatments, where mean yields were <30% of the control. Seventeen and 20 months after application, none of the herbicide treatments gave 100% control of Coolatai grass. Glyphosate applied at 2.16 and 4.32 kg a.i./ha in autumn and flupropanate applied at 4.4 kg a.i./ha in autumn or spring were the most effective in the long term, reducing Coolatai grass dry matter yields by 70-80%.
Hyparrhenia hirta (L.) Stapf (Coolatai grass) has invaded large areas of grazed native grasslands on the North-West Slopes of New South Wales (NSW) and is widespread along roadsides and travelling stock routes. It is commonly regarded as an invasive, weedy species with low forage value when it is tall and rank, but may be more palatable when kept short, green and leafy. A study (1990–2001) of a naturalised stand of Coolatai grass in the Manilla district of northern NSW examined its herbage mass (kg DM/ha), persistence (basal cover %), and grazing value under 2 contrasting grazing treatments: pastures that had either large amounts of dry, unpalatable herbage [light grazing at 5 dry sheep equivalents (DSE)/ha] or were short, green and leafy (strategic heavy grazing at a stocking rate of 37 DSE/ha). Effects of pre-grazing treatments (slashing, burning, and no defoliation) were also examined and data (litter mass, plant basal area, ground cover, and soil and litter microbial carbon and nitrogen) collected to assess the long term sustainability of these grazing systems. Sheep grazed the light grazing treatment for about 34% of the experimental period, with the strategic heavy grazing treatment being grazed for about 7% of the time. Over the experimental period this equated to 6752 DSE grazing days/ha for the light grazing treatment compared with 10 120 DSE for the heavy grazing treatment. Herbage mass in the heavy grazing treatment declined to <1000 kg DM/ha within 6 months of the start of grazing and remained below this level until December 1998 when stocking rates were switched (i.e. plots previously grazed at low stocking rate were subjected to the heavier rate and vice versa). In contrast, mean herbage mass in the light grazing treatment was generally >3000 kg DM/ha from November 1990–98, but a high proportion of this was dead standing material that carried over from season to season. Mean Coolatai grass basal cover was 9.5% in November 1990, increasing over time to about 25% in both grazing treatments by December 2000. Coolatai grass herbage accumulation was highly seasonal, ranging from as high as 70 kg DM/ha.day in summer to 0 in winter. In both grazing treatments, forage quality was low for both green and dead material, with mean crude protein being 6.0 (green) and 3.4% (dead). Digestible dry matter values ranged from 41 to 62% (green) and 32 to 51% (dead) and mean metabolisable energy values were 7 (green) and 5.3 MJ/kg DM (dead). After 8 years, the heavy grazing treatment had lower (P<0.05) litter mass, ground cover, plant basal area and soil microbial C and N levels than the light grazing treatment, but switching of the stocking rates restored most indicators, except the soil microbial values.
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