Technique innovation in soil carbon measurement

Increased global industrialisation and deforestation have placed enormous burden on our atmosphere and environment. For no other reason than future proofing soils against major climate variability – a possible side effect of growing atmospheric CO2, diverting more of this carbon (C) from our air to where it can do considerably more good seems very worthwhile. This has made soil carbon storage and its measurement such an important and intense area of current research activity. To know and fully understand the impacts of various land management practices on soil carbon building processes requires before anything further is said or done the ability to measure carbon stocks reliably. The enormous challenges are to do this for huge land areas with a sensitivity to see the real changes occurring with an awareness of the spatial, seasonal or other variations that may be as significant. This research study had set out to advance our understanding of soil carbon and its measurement. It has investigated what has gone before and is currently being done but also considers ideas on the horizon. From this base, several novel approaches have been taken to develop innovative methods of dealing with these immediate questions with an aim to easing the soil carbon data crisis. One of the major problems is the natural variability of carbon in soils over relatively small distances leading to uncertainties in carbon analyses which easily amplify in terms of carbon stocks. To capture this variability using conventional methods available today make on-the-ground measurement prohibitively costly. Specifically to deal with this problem a system named the Soil Carbon Bench (SCB) was developed at the centre of this research to cope with large amounts of soil and in fact to enable carbon analysis of whole cores by trusted combustion. This newly developed apparatus formed the core of the work and in its test-bed form has been tested on carbonaceous calibration materials and was then demonstrated on soil cores recovered from a trial field under lucerne rotation. Its accuracy has been equivalent or better than standard analytical methods and when evaluated in terms of its cost efficiencies and determining carbon stocks on the work to date it has done so with a smaller margin of error and at much lower cost. The relative costs of determining soil C stocks were estimated to be about 1/5 of conventional methods along with improved precision. Soil C data obtained with the SCB had a lower variance and C stocks could be replicated so that total C values per 50cm core were typically within 0.2g or 0.0003 kg/kg of the site mean. The research has succeeded at addressing the benefits of analysing whole cores and paved a way to more efficient carbon surveys that easily respond to any changing protocol requirements as may be recommended by bodies such as the IPCC. There are iv numerous other possibilities to test in conjunction with sampling designs and the support of emerging proximal techniques under experimentation. Another but related area was to elucidate reliable ways to differentiate and determine soil carbon forms which are of great importance when considering carbon pools and storage. Thermal analytical studies were not only an ideal complement to the development of the SCB but provided many insights into the thermal behaviour of soil carbon components relevant to these pools. While it provided useful information related to loss on ignition methods (an important alternative method for large scale soil determination) it has opened up further possibilities for productive investigation that encompass characterising soil components and organic matter (OM) stabilisation. In particular it has shown real potential for the determination of black carbon and bushfire residues not easily detected by other instruments, but important for calibrating rapid soil spectral techniques

Valuing reductions in water extractions from groundwater basins with benefit transfer : the Great Artesian Basin in Australia

Rolfe, JC ORCiD: 0000-0001-7659-7040The management of groundwater to generate net community benefits is challenging because of the complexity of impacts that can be involved, the varying interests of different stakeholder groups, time lags between changes in extraction rates and aquifer levels, and the level of technical and scientific uncertainty. In an economic framework, decisions about conserving groundwater reserves by limiting extraction rates should be made by comparing the benefits of conservation activities with the associated costs. However limited information about benefits and costs makes it difficult to apply a benefit cost framework to issues of groundwater management. This can be addressed to some extent by sourcing non-market values from other studies in a benefit transfer process. In this paper, benefit transfer techniques are applied to an evaluation case study about limiting extractions from the Great Artesian Basin in Australia. The results demonstrate some of the issues with the benefit transfer approach, and confirm that the publicly-funded bore capping program in Australia has been delivering net benefits to the community