Multi-disciplinary approaches suggest profitable and sustainable farming systems for valley floors at risk of salinity

Abstract

Australia’s traditional approach to salinity abatement has been to focus primarily on the control of recharge in land not at risk of salinity by incorporating deep-rooted perennial plants (e.g. lucerne, oil mallees and farm trees) into farming systems throughout the landscape. However, in the broad valley floors and sedimentary plains of Australia’s cropping regions (the areas most at risk of salinity), recharge is mainly a 1-dimensional process. Thus, offsite recharge management may have little or no impact on salinity outcomes for the areas at risk. The future of the broad valley floors will be most influenced by the management decisions of landholders in the valley floors. To be sustainable and profitable, farming systems on valley floors need to (i) target perennial plants to the valley floors and improve soil management to dry the root-zone, decrease recharge and minimise capillary rise, (ii) increase the discharge of groundwater from valley floors using deep drains and stands of perennial plants, (iii) improve surface water management to ameliorate waterlogging, inundation and flooding, and (iv) incorporate better plants and better agronomic methods in the growth of profitable salt tolerant crops and fodder plants. This paper will illustrate the convergence of new research and development that offers real prospects of low risk, high return farming systems for Australia’s threatened valley floors. We argue that there needs to be a major refocus by farmers, researchers and their funders in the development of profitable sustainable farming systems for valley floors.

Who's planting what, where and why – and who's paying?

“…Current thinking (e.g. George et al, 1999George et al, , 2004Barrett-Lennard et al, 2005) suggests that in lower rainfall, low gradient landscapes such as this one perennial vegetation is unlikely to be as effective in lowering water tables and mitigating the onset of dryland salinity in valley floors as was perhaps hoped when these plantings were undertaken in the 1980s and 1990s. The farmer's perceptions expressed during interviews, and those of other farmers in Western Australia (Kington and Pannell, 2003), largely concur with this opinion and this is no doubt one of the drivers behind the rapid decline in salinity as a motivating factor for revegetation over the period 2000-2004 (Fig.…”

Surface water as a cause of land degradation from dryland salinity

“…The less predictable nature of rainfall and runoff, high levels of socio-economic disadvantage and population growth and hydrological data paucity mean that drylands are under-developed in terms of hydrological infrastructure and conceptual understanding and are sites of water vulnerability (Koohafkan and Stewart, 2008). Their predominantly mid-latitude location is notable as a region recognised as vulnerable to a future climate projected to have declining surface and groundwater resources (Barron et al, 2012;Smettem and Callow, 2014;Smettem et al, 2013;McFarlane et al, 2012). Attempts to identify a clear classification and understanding of dryland hydrology have been discussed, with landscape properties and runoff regimes highlighted as potential key determinants of hydrology (Wagener et al, 2007;McDonnell and Woods, 2004).…”

Effect of supplementation with grain, hay or straw on the performance of weaner Merino sheep grazing old man (Atriplex nummularia) or river (Atriplex amnicola) saltbush

“…, 2001). Being both perennial and in active growth through the summer and autumn period, saltbushes have the potential to reduce leakage of rainwater to water tables thus potentially reducing the effects of dryland salinity (Barrett‐Lennard et al. , 2005).…”