final reportp Northern Beef Program Project code: NBP.329 Prepared by: Dr David Phelps (Project Leader) Benjamin C Lynes Peter T Connelly Darrell J Horrocks Grant W Fraser Michael R Jeffery Department of Primary Industries & Fisheries Date published: April 2007 ISBN: 9781 741 912 241 PUBLISHED BY Meat & Livestock Australia Limited Locked Bag 991 NORTH SYDNEY NSW 2059 Sustainable Grazing in the Channel Country Floodplains (phase 2) A technical report on findings between March 2003 and June 2006 This publication is published by Meat & Livestock Australia Limited ABN 39 081 678 364 (MLA). Care is taken to ensure the accuracy of the information contained in this publication. However MLA cannot accept responsibility for the accuracy or completeness of the information or opinions contained in the publication. You should make your own enquiries before making decisions concerning your interests. Reproduction in whole or in part of this publication is prohibited without prior written consent of MLA. Sustainable Grazing in the Channel Country Floodplains (Phase 2) Abstract ‘Sustainable Grazing in the Channel Country Floodplains’ was initiated by industry to redress the lack of objective information for sustainable management in the floodplains of Cooper Creek and the Diamantina and Georgina Rivers. The project has maintained links with the grazing community and has extensively drawn upon expert local experience and knowledge. The project has provided tools for managers to better anticipate the size of beneficial flooding arising from rains in the upper catchment and to more objectively assess the value of the pasture resulting from flooding. The latest information from the project has enabled customisation of the EDGENetwork™ Grazing Land Management training package for the Channel Country. In combination, these tools will assist in making earlier cattle stocking decisions, including when cattle may need to be mustered out of floodplain paddocks, how many additional cattle will be required to take advantage of the flood–grown pasture, and the timing of cattle turnoff. These will reduce costs by providing a greater lead time to plan cattle movements and purchases, and may enhance the sustainability of the resource base by better matching cattle numbers with the feed on offer. Page 2 of 158 Sustainable Grazing in the Channel Country Floodplains (Phase 2) Executive Summary ‘Sustainable Grazing in the Channel Country Floodplains’ was initiated by industry to help improve sustainable grazing management of the floodplains of Cooper Creek and of the Diamantina and Georgina Rivers. The floodplains are the powerhouse of beef production in the Channel Country, with 0.5–1.0 million head of cattle grown–out in the area each year. Floodplain pasture production is dependent on floodwaters from the upper catchment to provide ‘natural irrigation’ of the fertile clay soils. The pastures are dominated by soft, annual grasses and broad– leaved plants, meaning that production from the floodplains is truly ‘boom and bust’. High levels of pasture growth follow floods. Nothing but bare ground remains during extended dry periods. These extremes of pasture abundance require flexible management to ensure the sustainability of the natural resources base and future cattle production. Research to measure and model rainfall, flooding, soil moisture and pasture growth was conducted over 7 years at 17 sites located across the major floodplain country types of the Cooper, Diamantina and Georgina. These on-property sites were located on 13 Channel Country properties, with direct and in-kind support from pastoral companies and private land holders. The data collected has been integrated into tables of likely pasture growth, based on flood type and country type. Representatives from Channel country properties were involved in defining the project, setting the goals, and selecting locations for study sites. A Steering Committee provided practical advice and over-saw project direction, and also made important contributions to interpretation of data and design of communication products. Channel Country managers recognise four main types of flood: • Good (where 80% or more of the floodplain is inundated, providing for 85–100% of peak cattle numbers to be carried); • Handy (where 50–60% of the floodplain is inundated, providing for 45–85% of peak cattle numbers to be carried); • Gutter (where shallow channels, called gutters, spread the floodwater inundating 5-15% of the floodplain, providing for 5–25% of peak cattle numbers to be carried); and • Channel (where floodwaters just break the banks of the channels, inundating less than 5% of the floodplain and providing for 5–15% of peak cattle numbers to be carried). Pasture growth modelling provided estimates of pasture growth for combinations of flood type and country type. The three main country types, frequently-flooded plains, swamps and depressions, and open plains, relate to the frequency of flooding and position in relation to major watercourses. Swamps and depressions grow up to 8000 kg DM/ha following a Good flood, but only 1200-2500 kg DM/ha following a Channel flood. Open plains are most distant from the main river channels, flood the least often and have the least well-developed alluvial soils. At least a Handy flood is needed to reach the open plains, with pasture growth limited to 100–250 kg DM/ha. Growth on open plains following a Good flood ranges from 1500–3500 kg DM/ha. Pasture growth, botanical composition and forage quality vary depending on the season of flooding (winter or summer) and the weather conditions following a flood. For instance, hot and windy conditions can retard pasture growth by scorching seedlings and rapidly drying out the soil surface. Flood type and post–flood pasture growth conditions are therefore critical in determining the numbers of cattle that can be stocked initially, and how many can be carried to achieve desired liveweight gains. Page 3 of 158 Sustainable Grazing in the Channel Country Floodplains (Phase 2) A ‘flooding rules of thumb’ guide has been produced for the Cooper and Diamantina to allow managers to better anticipate whether a Good, Handy, Gutter or Channel flood will result from upper catchment rains, and the likely pasture growth that will result. A guide to forage value has also been produced which will assist in matching cattle numbers with available feed, and help achieve production goals while minimising risk of any deterioration of the natural resource base. Changes in pasture yield, ground cover and botanical composition within and outside of the 17 site exclosures were documented between 2002 and 2006. Over this four-year period, the over-riding influence has been moisture availability, with flood–induced pasture growth and cover declining throughout dry periods even in the absence of grazing. The only suggestion of grazing impact on vegetation was in areas of unusually high grazing pressure, such as within holding paddocks. However, such effects could not be confirmed within the four years of monitoring. These new guides to flooding and pasture management will be distributed to all Channel Country managers during 2007. These guides and other information from the project have been incorporated into a Channel Country version of the EDGENetwork™ Grazing Land Management training package. Training has been delivered since early 2007, with participants able to more objectively match cattle carrying capacity with the productive capacity of the land. These products will promote practices which help consolidate sustainable management of the Channel Country. Small gains in productivity in the Channel Country, with an estimated annual turnoff of $65 million, can lead to substantial financial gains for the region. For instance, a 5% increase in either cattle numbers or liveweight gains, would lead to an additional $3.3 million per annum, on average. The potential gains may indeed be higher, with single large floods reported to turn-off $150 million worth of beef. Other regions and researchers can benefit from the results of this project. For instance, the data used to derive the pasture growth tables can be used as the basis for testing the GRASP pasture production model in other annual pasture systems, especially those growing on clay soils. Page 4 of 158 Sustainable Grazing in the Channel Country Floodplains (Phase 2) Contents Page Abstract........................................................................................ 2 Executive Summary .................................................................... 3 List of Tables ............................................................................... 8 List of Figures ............................................................................. 9 List of Plates.............................................................................. 11 1 Introduction ....................................................................... 12 2 Project Objectives............................................................. 14 3 Background to the Channel Country .............................. 14 3.1 Physical Attributes of the Channel Country..................................................................... 14 3.1.1 Geographic Information ...................................................................................... 14 3.2 Biophysical Description of the Channel Country ............................................................. 17 3.2.1 Geology and landforms .....................................................................................