Technical annual report 2000-01
Dept. of Regional Development, Primary Industry, Fisheries and Resources technical annual report; Department of Regional Development, Primary Industry, Fisheries and Resources technical and annual report; Reports; PublicationNT; Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Agriculture -- Northern Territory -- Periodicals; Fisheries -- Northern Territory -- Periodicals
Dept. of Primary Industry and Fisheries
Technical bulletin (Northern Territory. Dept. of Primary Industry and Fisheries) ; no. 295
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Technical Annual Report 2000/01 253 PROJECT: Benefits and Costs of Water Ponding Banks Project Officer: C. Ballenger Location: Alice Springs region Objective: To record the potential benefits and associated costs of water ponding banks for increased pastoral production in central Australia. Background: Water ponding has been promoted as a means of land rehabilitation in central Australia. While there is anecdotal evidence of the benefits, there is little data on the value of these benefits compared to the cost of building the ponding banks. With the current financial squeeze that some central Australian stations find themselves in, it is important to have a clear idea of the costs and likely returns before committing time and money. Results: The Influence of Waterponding on the Pasture The pasture at the ponding bank site at Hamilton Downs was assessed in 1998 and then again in 2001 after the above average rainfall conditions. Figures 1 and 2 demonstrate that the response of pasture to ponding will vary with seasonal conditions. Total pasture biomass in 2001 was similar for ponded and unponded sites whereas in 1998 total pasture biomass was much greater at the ponded site compared with the unponded site. This suggests that during drier periods (e.g. 1998 survey) the response of the ponded pasture will be more noticeable than that of the unponded pasture. During wetter periods (e.g. 2001 survey) the greater amount of annual grasses present in the unponded pastures means that total pasture yields may be similar. Although the grazing value of the pasture in 2001 was greater in the unponded area than the ponded area, the greater amount of perennial grasses present at the ponded sites suggests that the ponding banks have created a more stable pasture condition. Ponded and unponded pasture was also assessed at Murray Downs (July 2000) and results were compared with prior pasture assessments undertaken in 1990, 1991 and 1994. After 11 years the ponding banks were producing higher pasture yields than non-ponded areas. At sites that were ponded, ripped, seeded with buffel grass (Cenchrus ciliaris) and grazed, total pasture biomass was over three times higher than sites without reclamation and at spelled sites with the same treatment, total pasture biomass was over 13 times higher than without reclamation. The results demonstrate that spelling greatly increased pasture biomass 0 500 1000 1500 2000 2500 ponded 1998 unponded 1998 ponded 2001 unponded 2001 D ry W ei g h t (k g /h a) forbs annual / short-lived perennial grasses perennial grasses Figure 1. Comparison of plant groups 1998 and 2001 0 500 1000 1500 2000 2500 ponded 1998 unponded 1998 ponded 2001 unponded 2001 D ry W ei g h t (k g /h a) unknown low desirability mod-high desirability Figure 2. Comparison of grazing value 1998 and 2001