"The main reason that manure is suddenly seen as a science is that chemical fertilizer prices are on the rise. The price of a specialty fertilizer like ammonium polyphosphate is nearly $1,000 a ton as I write. Deposits of potash in Canada, which we have long relied on for potassium fertilizer, are dwindling, and there is no other known supply as readily available. It has taken us about 100 years to reduce soil organic matter to dangerously low levels—from about 5 percent, on average, to below 2 percent—and experts say it might take at least that long to build them back up again using organic methods on a large scale. Getting all the manure and other organic wastes needed to maintain yields high enough to support rising populations without a full complement of commercial fertilizers would be an enormous challenge requiring new agricultural and cultural attitudes.... The laugh of the day now is that maybe manure will become more pricey than food—that the confinement operations will become, in fact and not in jest, manure factories that just happen to produce meat, milk, or eggs as by-products. "