4 ms·
Not to be rude but I don't think you are comprehending the scale of the problem. Where would the compost come from? A rough calculation (10 million ha, assume
by nas 16y ago
Not to be rude but I don't think you are comprehending the scale of the problem. Where would the compost come from? A rough calculation (10 million ha, assume a thin 80 mm layer of topsoil is lost, 1 mm of soil over 1 ha is 13 tons) estimates that 10 billion tonnes of compost would be needed per year to replace the lost organic matter.
It's a feedback system since good land produces lots of organic matter. Once eroded away, it's extremely difficult to restore. I have a hard time figuring out how we could avoid serious troubles in this area in the not too distant future. Some years ago there was a big push in North American to improve farm practices (stop burning straw, reduction or elimination of tillage, etc). That helped a lot but developing countries have not or cannot adopt such practices.
- eru 16y agoThanks for the numbers and details. By the way, what's so bad about burning straw? Or is it just that composting straw gives more soil?
- nas 16y agoI'm not sure we should turn this thread into a farming lesson but I'm happy to explain. ;-) Burning straw causes a lot of nutrients to end up in the atmosphere (see http://www.topcropmanager.com/index.php?option=com_content&task=view&id=1114&Itemid=182 http://www.topcropmanager.com/index.php?option=com_content&#...). It really is horrible practice but old habits die hard. It also reduces soil organic matter and the surface "trash" (broken up straw and chaff), making the top soil much more likely to be eroded by wind and rain. In the 1930's drought (the dirty thirties, the Dust Bowl) soil drifted in the wind like snow. North America had a worse drought in the late 1980's (http://en.wikipedia.org/wiki/US_Drought_of_1988 http://en.wikipedia.org/wiki/US_Drought_of_1988) but erosion was not really a problem due to much improved farming practices. Crop yield during the late 1980's drought were also much higher than in the 1930's because the new farming practice was much better at preserving soil moisture. That said, it was still not a fun time to be a farmer.
- eru 16y agoThanks. Farming is quite an interesting but underrated subject. E.g. the improvements in farming that eventually lead to the industrial revolution in England are rarely looked at.