A couple of useful technical pieces from the Australian Grains Research and Development Corporation.
What is soil organic carbon? “Although determining the total amount of organic carbon in soil is important, it does not tell us anything about the type of organic carbon present. For example, is the organic carbon dominated by pieces of plant residue or more recalcitrant charcoal?
“Understanding the partitioning of soil carbon within these different forms will help define the vulnerability of the carbon to subsequent change and the contribution that soil carbon may make to soil productivity. Therefore determining both the amount and the composition of soil organic carbon will be required to understand the implications of management practices on soil carbon stocks and vulnerability to change and on soil productivity.”
And an interesting piece on soil water use monitoring and crop management. “Practices available to farmers to improve transpiration and transpiration efficiency include selection of drought-tolerant species, manipulation of crop morphology, reduction of weeds, pests and diseases and the use of cultural practices such as sequences of different crops, time of sowing, intercropping, use of fertilisers, fallowing, reduced tillage, stubble retention and water harvesting.
“Tools available for farmers to monitor water supply and use include direct soil sampling techniques and indirect water monitoring sensors. Direct sampling is typically prohibitively expensive but various low-cost sensors suffer from a technology divide. Simulation modelling is now a well established technology to assist in crop management decision making, but this too suffers from a technology divide.”