Saturday, June 22, 2013

How much closer to soil carbon trading can CSIRO take us?

What do you do when you feed into a computer soil carbon data from more than 20,000 samples from more than 4,500 locations and a range of land uses and management regimes and what comes out is... gibberish? No meaningful pattern? This happened with SCaRP. It failed to detect statistical difference in soil carbon rates between land management practices. (See 'No difference was detected...' below)

What would you conclude? Taken literally - as some experts did - means you would be accepting the absurd proposition that farmers can treat soil anyway they want, it won't change soil carbon levels. If so, where did 70% of the nation's Soil Organic Matter go since 1770? Aboriginal Agriculture? Or over-grazing, over-ploughing by farmers who learned to farm in Europe?

Would it be safer to ask the question: "Did we ask the wrong question?" Instead of asking which land  management regime builds soil C faster and further, they could ask: "Which farmer has built soil C faster and further, and how did they do it?" 
This is now our focus.

‘No difference was detected …’

  between high and low  P fertiliser inputs to pastures. Central tablelands NSW
  between set stocking and rotational grazing (Central tablelands NSW
between pasture cropping and permanent pasture. Central slopes  NSW
between native pasture (tropical pasture , tillage minimum tillage.  Northern slope and plains NSW
between native grass , lucerne , Rhoades grass and Premier digit .  Northern slope and plains NSW
between cropping with organic fertilisers and chemical fertilisers.  Northern tablelands NSW
between rotational grazing  and set stocking pastures. Northern tablelands NSW
between tillage, stubble and fertiliser treatments. Hermitage research trial Qld
between conventional tillage and no-tillage systems. Goodger research trial  Qld
between conventional tillage and no-tillage systems. Biloela research trial  Qld
between stubble retention and stubble burning at MacKay and Bundaberg trials. Sugarcane Qld
between grazing pressure treatments on SOC stock, Wambiana grazing trial Qld Rangelands
between cell, rotational or continuous grazing management practices , Qld
between phosphorus application or stocking rates. Hamilton Vic
between continuous grazing, optimised deferred grazing, and timed grazing. Ararat Vic
between applied stubble management and tillage treatments Horsham Vic
between annual pasture  and perennial pasture . Esperance WA
between stubble retained  and stubble burnt . Merridin WA

Analysis of results of the $24m Soil Carbon Research Program has led some to the conclusion that management cannot affect carbon levels in soils.

The Case For Soil Carbon

There is no rule book for different land management practices. What one farmer calls ‘rotational grazing’ another calls ‘cell grazing’ and another ‘time-controlled grazing’ or ‘grazing management’. Or ‘high intensity/short duration grazing’.  And every farmer adapts techniques according to their skills, knowledge, and experience. None of these variables were considered in the study. But  Dr Jeff Baldock, in his report on SCaRP, seems to conclude that the manager rather than the management system that makes the difference: “Consider the situation where the water use efficiency of continuous cropping systems ranges from 60% to 90% across a region due to landowner abilities and preferences. Under these conditions, differences in the input of carbon to a soil will result and soil carbon values will vary even under similar soil, climate and topographic conditions.”

It's the farmer, not the farm management system. It's the knowledge, expertise and experience of the manager. This is where the next wave of research should be focussed.

Finally, when a farmer practices Carbon Farming, they don’t do it one activity at a time. They might have six or more soil-carbon-boosting practices active on the same paddock over a reporting period of 5 years. Yet studies will single out one of them and try to measure the results. This problem arises because of the choice made between two approaches to measuring sequestration: Activity-based (isolating each practice for separate analysis) and Outcome-based (simply measuring the change in soil carbon levels for a defined piece of land). Insurmountable complexity and cost attend the one the IPCC chose where Common Sense would recommend the other.

No comments: