7. Accounting for Erosion: More complexity

7. Accounting for Erosion: More complexity

Problem: The Department is planning to force soil carbon methodology proponents to measure the impact of erosion and deposition on the calculation of on-farm abatement.  “How could erosion/deposition be included in the abatement calculation?” Erosion (and hence deposition) is caused by soil being exposed to the elements. Soil carbon cannot be accumulated when earth is bare.  Thus it can be assumed that there will be an inverse correlation between soil erosion (reductions) and soil carbon (increases). The good carbon farmer receives topsoil from paddocks of poor farmers. It would add unnecessary complexity to try to calculate the soil trading account. (See APPENDIX D) Practical solution: Abandon the requirement to track erosion and deposition and account for it in carbon accounting on farm. It would be conservative to do so.

APPENDIX E: Urgent need for action on wind erosion

A good example of the way a lack of proportion can create unnecessary complexity and thus delay can be seen in the case of dust. In a recent Soil Carbon Stakeholders Reference Group Meeting, Draft Sampling Design Method and Guidelines, Annotated Agenda, 8 November, 2013: “Note that a full methodology will contain information on how to calculate project-level abatement including the treatment of uncertainty and erosion…” The Department has discovered yet another area of uncertainty that will delay soil carbon offsets trading while scientists find a way to incorporate this new reason to discount a farmer’s return on soil carbon increases into the calculation of on-farm abatement.

Although CSIRO research scientist Dr Adrian Chappell says: “soil organic carbon lost through dust is not a major contributor to Australia’s total emissions”, he goes on to list a series of facts that make it sound like it is and the only solution is more scientific study. These facts include the following:

• Dust contains carbon and clay which hold the bulk of soil nutrients. 

• Dust emission depletes soil nutrients at the source… and enriches soils where dust is deposited. 

• Carbon stored in our soils helps sustain plant growth. 

• Millions of tonnes of dust and carbon are blowing away.

• It is uncertain where all that ends up.

• With the frequency and intensity of dust storms likely to increase in Australia, the impact of wind erosion would also increase.

The inevitable conclusion then follows: “This redistribution of carbon needs to be better understood so we can improve our land management practices to better protect our soils.” Naturally we cannot trade soil carbon offsets while these newly-discovered levels of uncertainty remain unstudied and unresolved. 

But Dr Chappell’s paper could just as well be a call to action to use our existing knowledge to make an immediate impact on the levels of soil carbon loss. We already know how to protect our soils from erosion: increased ground cover. And we know where we need to see this increase: on agricultural lands.  And we know how to achieve it: get farmers to change their land management practices to reduce over-grazing and unnecessary baring of earth by cultivation and ploughing.  This change in behaviour will increase soil carbon levels – and farmers can earn soil carbon credits. In fact, we are on the point of achieving a methodology so farmers can start to earn soil carbon credits by changing their land management practices, increasing ground cover and reducing wind erosion.

We welcome Dr Chappell’s action in highlighting the role of the agricultural land manager in the source of wind erosion and soil losses: His work underlines the need for an effective incentive to change the behaviour of many land managers. “Wind erosion is a natural process, exacerbated by land management practices. Dust is lost from agricultural lands when management decisions that affect the percentage of ground cover retained and the soil aggregation level have not taken into account climatic conditions,” he says. “Circumstances which encourage sustainable land management have improved greatly, but not all land holders have adopted these management practices, and it is for this reason that accelerated wind erosion still occurs. 

“Wind erosion levels increase dramatically when ground cover levels (the percentage of soil covered by vegetation) drop below 50 per cent (Leys 1999). Land management practices that lead to overgrazing and excessive cultivation of ground cover can result in cover levels below 50 per cent, and during drier periods this increases the likelihood of wind erosion. In February 2012 the largest dust event in NSW since early 2010 was associated with burning and cultivation of cropland, which resulted in low ground cover levels in north west Victoria and far south west New South Wales (Office of Environment and Heritage 2012, http://www.environment.nsw.gov.au/resources/dustwatch/DWNL120430.pdf).

Dr Chappell’s research paper “Soil organic carbon dust emission: an omitted global source of atmospheric CO2” was published in the journal Global Change Biology.