A generation later, Charles Mitchell still recalls the discarded gum wrapper floating down the irrigation ditch in a carefully tended vegetable garden located at a on the campus of a Chinese agricultural college he was visiting in 1987.

In fact, for Mitchell, a soil scientist, the sight was a bit of an epiphany. The night before, he had casually flushed this discarded wrapper down the toilet of his living quarters, located only a stone's throw away from the garden.

The waterborne wrapper was a quaint reminder of the indispensable role waste — not only livestock but human waste — has played in fertilizing crops throughout four millennia of farming.

Now, after a long hiatus and in the midst of one of the most serious energy crunches in history, some farm observers believe that farmers in the United States and the rest of the West will soon view manure with the same respect as their counterparts in the East.

To and increasing degree, they already are, contends Gene Logsdon, author of "Holy Sh*t: Managing Manure to Save Mankind."

Indeed, as Logsdon sees it, the title of his book precisely expresses what Western farmers must learn to do over the next few decades: use and manage manure as a critical source of soil fertilizer.

The era of cheap manufactured and mined fertilizers is drawing to a close. Farmers, however reluctantly, will be dragged back to the future, back to a time when animal and even human manures comprised the primary sources of fertilizer, he maintains.

As a prime example, Logsdon cites ammonium polyphosphate, which climbed $1,000 a ton while he was writing the book. The rising costs of natural gas, the major source of nitrogen fertilizer, is also complicating matters as more people turn to it as a fuel substitute.

For these reasons, the day may be fast approaching when farmers will have to rely on animal and even human waste to maintain the necessary soil fertility levels, he says.

Logsdon and others even contend that a book, F.H. King's "Farmers of Forty Centuries," outlining Chinese and Korean practices for securing, managing and applying manure will be the manual of farming in the 21st century.

Other sweeping changes will follow, Logsdon contends.

For example, as costs of commercial processed fertilizers spike, he foresees that a growing number of row-crop farmers, desperate for manure, will augment their farms with concentrated livestock operations. Meat production will only be a secondary concern, Logsden contends.

For many Western row-crop farmers, this raises the inevitable question: Will things really get this bad?

For his part, Mitchell is a true believer in the value of animal manure. He's been preaching its merits to farmers for years, occasionally expressing frustration over farmers' reluctance — up to now, at least — to make greater use of it.

But while a true believer in the value of animal manure, he isn't willing to go as far as Logsden.