My intermittent blog over a number of years has questioned some of the new orthodoxy on soil management, carbon sequestration and soil fertility. This is based on studies of a number of long-term comparative trials, my Churchill Fellowship travels, monitoring of client farms’ soils and a challenging disposition. For example I have shown that “no till” does not necessarily result in greater total soil organic matter levels, many, if not most of the claims for substantial carbon sequestration in a matter of 5 or 6 years are nonsense (in any case most do not have the necessary robust monitoring systems in place), there is insufficient evidence to support the use of comprehensive, cation exchange capacity based soil analysis and some of the high mineral fertiliser-input “organic” systems that they support are inappropriate, the management of soil fertility through manipulation of soil life (fungi and bacteria) is not proven. Organic farming, though of course much better from the point of view of long-term fertility, prohibition of agro-chemicals and healthy food production, does not necessarily result in ongoing soil carbon sequestration – sequestration is dependent on the initial soil organic matter (SOM) level, soil type and climate as well as the management. SOM accumulation is a slow process and does not continue indefinitely, it reaches a plateau.
This recent blog https://realorganicproject.org/tim-bowles-climate-smart-includes-tillage-episode-one-hundred-fifty-seven/?mc_cid=8d69405b72&mc_eid=bbc50f020b from Tim Bowles, soil ecologist at UC Berkeley with the admirable Real Organic Project in the US backs up some of my comments. Of particular note is that tillage is not necessarily bad and that “tillage …. promotes nutrient cycling” and “healthy soil advocates should be more concerned with cover crop practices than tillage”. Soil organisms, notably mycorrhizae, are very resilient to some tillage.
