In December I attended a small workshop organised by Grains Research and Development Corporation (GRDC) to build linkages between farmers and soil biology researchers and decide priorities for the next round of soil biology research.

Researchers from around Australia attended, along with GRDC panel farmers and some innovative farmers whose farming systems are surviving in drought thanks to the health of their soils.

Boorowa grazier, David Marsh, has divided his farm into about 90 small paddocks, each of which is grazed by his entire flock every few months, for a total of six to 10 days a year. This gives the pasture and soil time to recover between grazing, so that even in this severe drought his soils are producing feed for his sheep.

Colin Seis is a pasture-cropper from Gulgong who grazes his sheep on summer native grasses and in autumn direct drills cereal rye and oats into the dormant summer grasses after they have been trampled and dunged by the sheep. In 2006, he made a profit of $360 per hectare on the crop, and had grass for his sheep.

His crop inputs are very low, around $90/ha and dropping, and no pasture resowing is needed. Interestingly, he is taking more phosphorus off in his crop than he is applying, suggesting that soil organisms may be accessing phosphorus not usually available to plants. Research into his soils has found improved water and nitrogen use efficiency, and an increase in total plant biomass.

The scientists at the workshop reported on their research areas which include soil organic carbon, carbonnitrogen interactions, croppasture rotations, soil biology functions in cropping soils, plant roots, endophyte organisms, free living nitrogen fixation, and the role of soil organisms in accessing residual phosphorus.

For me, one of the key messages to come out of the workshop is that measuring total organic carbon does not tell farmers the full story about their soil health.

South Australian CSIRO researcher, Jeff Baldock, and Western Australia researcher, Fran Hoyle, who works with the Department of Agriculture and Food WA, both stated the importance of measuring the different carbon fractions because they have different functions in the soil.

The labile or active fraction depends on plant residues, decomposes rapidly into mineral form for plant use and responds fastest to management.

The humus fraction takes decades to turn over; while inert organic matter such as charcoal takes thousands of years to decompose.

It is important to know the differences, because, while two soil samples may show similar total carbon levels, one may have all the carbon locked up as humus while the other may have much more labile carbon readily available for decomposition.