Renewable Farming

A nearly forgotten, biologically based way of building long-term productive soils

When I introduced the first “Renewable Farming” seminars in the early 1980s, keynote speaker Dave Larson emphasized: “Calcium is the king of nutrients.”

Jan. 18, 2017  By Jerry Carlson — Another champion of Renewable Farming, Dan Skow, also focused on the second most critical building block for crops: CarbonThe importance of calcium and carbon faded over the following three decades as commercial fertilizer firms pushed NPK as about all you need.

Now, a new generation of crop advisors — informed with new types of soil tests — are confirming why available calcium and carbon are vital for high-yielding crops. 

Crop consultant Jerry Scheppele of Garnavillo, IA told farmers at a mid-January meeting: 

— For high yields, your soils need 300 to 500 parts per million of soluble carbon, as shown on the Haney soil test. Midwest Labs will do this test.

— You need 200 parts per million of soluble calcium showing on your water-soluble calcium test. Midwest also does water-soluble analysis for about $10 extra beyond your standard strong extraction soil test.

Jerry Scheppele

Soils showing those carbon and calcium numbers have the foundation for prolific, balanced soil microbiology. And it’s the beneficial bacteria and fungi which make all other nutrients soluble so your crops can take them up. With this balance in place, soils can produce 210-bu. corn with only 80 units of added nitrogen. 

“It’s not about fertilizer, guys. It’s about carbon,” Scheppele told farmers. “Growers with carbon readings of 300 parts per million on the Haney soil test are getting 400-bu. corn. But they are not applying more total fertilizer. Farmers who work with these principles see their soil fertility tests improving. Their soil organic matter tests are climbing as they raise big yields. And they don’t need more fertilizer to gain those yields.”

AgriEnergy Resources General Manager Dean Craine is also emphasizing that point in winter seminars like the one which the firm led in Georgia Jan. 5. Dean’s presentation was titled, “Carbon: The Essence of Soil Fertility.” Dean showed farmers proof that by wise carbon management you can reduce your purchased NPK rates, boost your soil organic matter and CEC, and increase the value of your farmland.

Even though a big corn crop generates large amounts of raw carbon, most of it is metabolized by microbes or oxidized by weathering. Either way, it escapes as carbon dioxide. Scheppele adds, “Every pound of excess nitrogen applied as artificial fertilizer destroys 100 pounds of humus.” The nitrogen stimulates carbon-consuming bacteria. This is explained in the book, Carbon Connection by Leonard Ridzon and Charles Walters.

The yield-effective carbon you need is in biologically active form, often referred to under the generic term “humates.” This carbon structure:

— Transports micronutrients

— Increases microbial populations by greatly expanding habitat for them

— Improves moisture retention

Scheppele pursued several humate sources and currently works with the Black Earth firm from Canada. The humic material exported by Black Earth for ag use is 80% soluble, with a higher oxygen content than most humate materials, which are essentially oxidized coal. It’s most effective when spread in the fall with your dry fertilizer. 

Active carbon is an excellent chelator to sequester iron in the soil. This helps prevent iron from tying up calcium and phosphorus. Soluble carbon can also stabilize and buffer foliar nutrients, such as calcium nitrate.

Scheppele tested how the Black Earth humate material could help a field testing only 33 parts per million carbon on the Haney analysis. He applied 500 lbs. per acre, which is a heavy rate compared to the usual 100 lbs. or so. The carbon test rose to 160 parts per million (ppm.)

That big of a move takes more time with a modest annual application of Black Earth humate.  However, when soil tests move into the 200 to 300 parts per million range of soluble carbon, biological life will probably become so active that you won’t need to add further humates.  Cover crops will accelerate this process. Anhydrous ammonia raises soil pH and “ties up a lot of carbon.” says Scheppele.

A healthy balance of soil microbes is about half bacterial, half fungal. You need both, says Scheppele. Today’s chemicals tend to decimate the bacterial balance. Mycorrhizal fungi break down the stalk cellulose and lignin, while bacteria digest the softer pith parts of crop residue. An active form of humus, called Glomalin, is made only by mycorrhizal fungi. 

Scheppele observes, “When abundant mycorhiza are in the soil, it helps hold calcium up.” 

A humate-building program should start in the fall, with a residue breakdown “inoculation” of digesting microbes. If you’ve never tested the effect, do a test plot, and do the Haney soil test year after year.

Black Earth humate is about 30 cents a pound to 35 cents; this should go on with the residue digestion program, and calcium nitrate with the humate. Schepple concludes, “It’s exciting to see our farmers growing huge crops and lifting their soil quality at the same time. It’s not based on the old “replacement” theory of fertilization. Soil biology does the work.”