Soil — Stop Treating it Like Dirt
There is an article in the latest online issue of National Geographic — in fact it is dated next month (September ‘08) — titled Our Good Earth. The last third of the article is about Terra Preta and Biochar, but the earlier parts are also interesting observations on the practical considerations farmers have to evaluate when treating their soil. Like the compaction caused by large farm equipment. And elsewhere human-induced erosion and desertification. By 2030 there will be over eight billion people on this earth, and we will need 30% more grain than we currently grow, which will be difficult if we continue to lose soil at the current rates.
But the article isn’t all doom and gloom. The author looks at China, where terracing has created tremendous erosion problems — but he finds a place where they are creating solutions, returning the steepest slopes to natural grasses and trees, using moderate slopes for orchards rather than field crops, and growing their fields of millet and sorghum and corn on the lower, nearly level soils less prone to erosion.
Next the author turns to Africa, where he describes the success stories of the Sahel region, where here and there a drop of hope springs forth in an otherwise barren land. He describes huge and expensive projects sponsored by foreign governments, and simple local projects where farmers use traditional methods to restore soil fertility. Like cordons pierreux. In that process, long lines of fist-sized rocks are lined up on the hard crusted soil. As rains wash over the gentle slopes, the rocks hold it long enough to let some percolate into the ground, and to allow silt to settle out of the roiling waters. Plants grow in the silt, which in turn slow the water more, so that in time trees and shrubs grow.
Another traditional method involves digging holes in the field, and filling them with manure. Termites eat the manure and convert it into compost (termicompost?) while burrowing channels in the soil, loosening the texture. Trees planted in these holes then grow strongly, and their roots help break up more compacted soil, and their leaves add nutrients when they fall.
Finally, the article turns to Terra Preta and the promise of biochar. My title for this post is stolen directly from the last line in the article, a quote from geologist David Montgomery, from the University of Washington. We really do need to pay better attention to our soils, and give them the care they deserve. Who else is going to feed us?