Healthy soil, according to a federal agency, "should look like chocolate cake with airholes permeating throughout."
Those choice words are part of a campaign to urge farmers to care for the dirt where they plant their crops.
The Natural Resources Conservation Service aims to prevent compaction, erosion and other problems that can do long-term damage to productivity.
It matters to nonfarmers, too, not just because we eat, but because we drink and breathe. Soil that blows off fields or runs into streams can pollute the air and water.
"We take it for granted," said Dennis Chessman, state agronomist for the NRCS, from his Davis office this week. "It's pretty easy to do that because we don't pay attention to what's going on underground."
What's going on, under natural conditions, is amazing. Plants take root in a mix of minerals, tiny rocks, decaying vegetation, manure and organisms ranging from bacteria to earthworms. Some of the creatures eat other creatures. Some eat the plant and animal debris, breaking down the nutrients and enriching the soil.
"There are as many living organisms in a teaspoonful of healthy soil as there are people on Earth," the NRCS says in a 2013 calendar that is part of the campaign.
The calendar also features the quote about good soil being like cake. And it mentions geosmin, a microbial byproduct that gives soil "a sweet, earthy aroma like nothing else."
(Why can't the federal government write with such grace in, say, the instructions for Form 1040 from the IRS?)
Chessman said farmers can do damage by plowing excessively or leaving the fields bare after harvest. Synthetic fertilizers used since the 1940s have maintained some of the nutrients, he said, but they are not a long-term answer if the soil structure is not sound.
The agency urges farmers to leave residue from the previous crop on the ground, such as corn harvested in fall to make way for winter oats.
They also can plant cover crops between rows of trees or vines, especially clover and other legumes, which make airborne nitrogen available to roots.
Some farmers in the Northern San Joaquin Valley have adopted these practices, but Chessman said he is surprised that they are not more widespread.
The practices can maintain crop yields while reducing costs, he said. Farmers who minimize plowing save money on fuel, labor and tractor wear and tear. Healthy soil also can retain water in times of drought and drain it steadily in times of deluge.
These ideas might seem to raise doubt in the synthetic fertilizer industry, which has made plenty of money from nutrients derived from natural gas and other sources. Chessman said that's not the case.
"They're selling fertilizer, but they're also recognizing that the proper use of it is important," he said.
The Western Plant Health Association, which represents the fertilizer industry, supports the NRCS effort, communications director Richard Cornett said by e-mail.
The Sacramento-based group is not involved in the campaign, but it did co-sponsor a Modesto conference in October at which similar ideas were discussed. The main thrust was that fertilizer should be applied at the right time and at the right rate to prevent water pollution and other problems.
The NRCS started as the Soil Conservation Service amid the Dust Bowl of the 1930s. It dealt with the effects of windstorms that stripped soil from many Great Plains farms and sent refugees to the San Joaquin Valley and other places.
The agency has refined the science of soil in the decades since science that can be complex. It also knows that simple images can get the message across, such as this one about soil that is properly porous:
"And of course you should see earthworms our wonderful soil engineers!"
On the Net: More information about the initiative, Unlock the Secrets in the Soil, is at www.nrcs.usda.gov
Have an idea for the Farm Beat? Contact John Holland at firstname.lastname@example.org or (209) 578-2385.