This proposal starts with the use of agricultural lime to neutralize the sulphuric acid, and then the seeding of native plants to stabilize the soils and thereby keep further acid from being exposed. This process has been used successfully in other areas for this purpose, and it would possibly work the Lakes. However, what has not been appreciated is the vast scale of such works, since the acidic soils are widespread over the exposed Lake beds, and these are increasing in area daily as we move on into late summer without rain in the catchment, and soaring temperatures exacerbating the evaporation. River Murray levels at MurrayBridge on February 13, 2008 were 1.3m below sea level.
The amount of lime that would be needed even now, let alone in the future when the exposed areas are likely to be much greater, would be enormous, and probably only treat the top few cm of soil, leaving the sulphides in the metres of sediment below untreated and waiting to be oxidized should there be an event that kills the plants (eg, extreme heat or lack of rain). The actual process of spreading the lime would be a huge job and very expensive. Also to be considered is the process of production of lime, which is formed by heating limestone, releasing carbon dioxide to leave the calcium oxide. It is therefore an energy intensive process, and greenhouse unfriendly.
Seeding the soils depends on the availability of correct species of seed in huge quantities. Where will this come from, how soon can it be obtained, and how much will it cost? Collecting seed for revegetation is a very labour intensive and time consuming process, and there is much doubt whether it can all be done in the quantities needed. Then the seed would need a certain amount of rain in the winter to germinate, and through the year to keep alive. It is true that plants have naturally colonized the newly exposed Lake bed over the last two years, and perhaps this would continue to occur without any artificial seeding. However, it is likely that as the water recedes further, those newly exposed soils will be more and more saline, and therefore more and more difficult for plants to survive.
Elizabeth Gordon-Mills, Phd