Agriculture Reference
In-Depth Information
which also turns arable over to ley farming, ought to make some soil carbon savings over
the Chemical Livestock scenario in Table B without resorting to ghost carbon; but this is
achieved by reducing permanent pasture, reducing beef and lamb consumption rather than
dairy, and bolstering pork production with food waste (which Azeez advocates should be
composted).
It is also possible that an organic ley farming system, boosted with a judicious amount
of chemical nitrogen fertilizer, would achieve higher yields and economize sufficiently on
land for the soil carbon so accrued to outweigh the carbon emissions generated by the man-
ufacture of the fertilizer. That largely depends upon whether or not artificial nitrogen has an
of course, is not open to purist advocates of organic farming, who need most of all to find
ways of increasing yields.
The above difficulties are all connected with changes in land use. There remain other im-
provements that can be made without taking up more land, for example using cover crops,
employing compost or farmyard manure in preference to slurry, or possibly the adoption of
minimum tillage techniques. However, with the possible exception of cover crops, it isn't
uncertain whether any of these, even if carried out on a grand scale, would have the poten-
tial to alter the balance of soil carbon very noticeably without a simultaneous expansion of
legume based leys.
I therefore incline towards the opinion of scientists at Rothampsted who conclude one of
their reports with the words: 'We believe that there is too much emphasis on soil C sequest-
ration and too little attention to major climate change threats such as land clearance for ag-
riculture (food or biofuels) other forms of deforestation and wetland drainage'. A far more
effective and immediate way to reduce global carbon emissions from agriculture would be
to stop importing soya, rainforest beef and palm oil.
If soil carbon sequestration is to have any serious and rapid effect upon climate change
then it has to function at an order of magnitude higher than the modest levels advanced by
mainstream scientists, and achieve results like the 14.4 tonnes recorded in improved grass-
land in Colombia, or the 23 tonnes that Christine Jones seems to think can be gained from
bi-cropping grain with perennials, or the rich black humus that Yeomans claims to be able
to create out of Australian dust. That is why, despite my scepticism, I have spent some time
describing their efforts. These people attract adherents because they claim to have found
what we all hope exists - the 'win-win' solution that combines increased yield with eco-
logical benefits. It's not impossible, that is what the discovery of the properties of clover
and lucerne gave us, with huge benefits and no ill effects (except more nitrous oxide emis-
sions). The impact of the Haber Bosch process has been just as radical but not as benign.
Biodynamic farmers consistently outperform both organic and chemical farmers in the tri-
als reported by Azeez, and while this can be attributed to their use of compost, maybe it
