Australia's Grain Research & Development Corporation (GRDC) has noted that dryland cropping is dependent upon the amount of available carbon, which is used by soil microbes as a source of energy. Australian soils tend to be deficient in biologically available carbon but additional carbon inputs may come from crop residues or from the root exudates of growing plants.
Although there is a natural ability for most soils to suppress the spread of soil-borne root diseases to some extent through the activities of soil microbes, this can be assisted through the retention of crop stubble. It was found that the development of disease suppression occurred at a faster rate under no-till . Compared to low input wheat/pasture rotation, high input canola/wheat rotation showed a significant increase in soil microbial activity and increased nitrogen fixation.
The GRDC article quoted ( http://www.grdc.com.au/director/events/onfarmtrials?item_id=4829E00ABA74196DBA6E6720DD31B660&pageNumber=3 ) contains additional data on the trials held which also indicated that no-till practices led to improved binding of soil aggregates by fungal hyphae (because the fungi are able to grow better without disruption from tillage).
Photo of Joel Williams, at Laverstoke Farm laboratory in the UK.
Supporting the idea that no-till practices provide a positive boost to soil biology, Joel Williams of Laverstoke Farm (the "University of Organics") notes that farmers' livelihoods depend upon the health of their soil.
"Its health is a balance between the chemistry, structure and biology of the soil, and they are interlinked. So you need to think what the impact will be of management decisions on all three."
Soil microbes carried out many important functions in a healthy soil, he said. Those included digesting and recycling organic matter, improving soil structure and increasing water and nutrient holding capacity.
They were susceptible to fungicides, fertiliser-rich soils and some herbicides, such as glyphosate, he said. However, avoiding soil disturbance was the biggest benefit to their survival. "Soil fungi, in particular, don't like being disturbed. Ploughing smashes up the fungal hyphae, so you have to start again."
Laverstoke Farm hosted a couple of workshops in November 2009, featuring Dr Elaine Ingham of Soil Foodweb, Inc.
Joel's comments can be read at Farmers Weekly Interactive - http://www.fwi.co.uk/Articles/2010/05/12/121199/No-till-methods-help-protect-soil-biology.htm and the Laverstoke Farm website is at http://www.laverstokepark.co.uk/home
In another project just starting, the GRDC is looking at what is required to obtain the best financial returns in the long-term with no-till practices. A project expected to last 12 years in Western Australia and using two different soil types (heavy soil, sandplain soil) will consider a range of no-till practices. University of Western Australia researcher, Ken Flower, indicated that researchers will be trying to identify how much residue is required to provide the optimal benefits in the long-term.
“The Australian grains industry still needs to know how much residue is sufficient to maximise the long-term benefits of no-tillage systems,” he said.
“The GRDC funded project is a farming systems trial pulling together all the different components of the no-tillage system to find out if the different systems are profitable in the long-term, store more soil carbon and use water more efficiently.”
Read the full press release at: http://www.grdc.com.au/director/events/mediareleases?item_id=AA3B1EE4CE2A862EF99D190CBA03C04F&pageNumber=1
For those with a high-speed internet connection, the following website has a 24 page booklet outlining many of the benefits obtainable from no-till. See http://panutrientmgmt.cas.psu.edu/pdf/rp_better_soils_with_noTill.pdf In the "picture worth a thousand words" category, check out the photograph on Page 6 showing run-off from side-by-side no-till and conventional tillage fields at Milan Experimental Station (University of Tennessee). Seventy percent of Tennessee farmers now use no-till. The largest no-till field day in the US is held in Milan in July - http://milan.tennessee.edu/MNTFD/
Website for the West Australian No-Tillage Farmers Association (WANTFA) is at http://www.wantfa.com.au/about.php