Want to improve your soil quality quickly? Start practicing residue management and keep a close eye on your nutrients and micro-organisms. “Residue breakdown is the best way to start next year’s crop,” said Jerry Scheppele of Full Sircle Products, located in northeast Iowa.

Scheppele, a certified nutritionist, ag consultant and organic farmer, was among the presenters at the GrassWorks Conference held annually in Wisconsin.

An acre cornfield yielding 160 bushels per acre will leave behind enough crop residue (roots, base stalks, etc.) to put $100 worth of nitrogen (N), phosphorus (P) and potassium (K) into the soil – if it is managed correctly.

There are a number of variables which can affect the quality and quantity of the crop residue, from the height of the plant to the amount of foliage.

Scheppele explained that getting the N, P, K value back into the soil requires maximizing crop residue breakdown by stimulating micro-organisms, mycorrhiza and aerobic bacteria populations.

Giving the micro-organisms in your soil what they need will prevent the nutrient value of your residue from rusting away (being affected by fungi in a detrimental way) or oxidizing away (increasing oxygen and decreasing hydrogen).

“Crop residue breakdown is the best way to start getting ready for next year’s crop,” he said.

Reducing soil compaction as much as possible and having readily available soluble calcium will help the N, P and K to end up in the soil, Scheppele said, as well as having the right energy and carbohydrates for growth of microbes.

Scheppele said setting up a nutrient recycling program will lead to overall healthier plants. More water and nutrients will be available in the soil, and there will be better utilization of sunlight with fewer inputs, thus giving you more yield and profit.

He defines a nutrient recycling program as giving the micro-organisms in the soil what they need to convert crop residue into nutrients.

Scheppele recommended the following applications in the fall on conventional fields to pump up soil micro-organisms so they can best utilize the crop residue (rates per acre):

• 3 gallons 28 percent nitrogen
• 1 gallon calcium
• 1 gallon ammonium thiosulfate (12-0-0-26)
• 3 to 5 pounds sugar
• Recommended amount of a bio-stimulant
• 2 to 4 ounces fish fertilizer
• 1 pint to 1 quart humates
• 1 gallon soluble potash (0-0-45), if needed, based on soil testing

On 1 acre of organic cropland, Scheppele recommends the following for fall application:

• 3 to 4 gallons Chilean nitrate
• 6 ounces fish
• 3 to 5 pounds organic sugar
• Recommended amount of bio-stimulant
• 1 to 2 quarts humates
• 2 pounds calcium, preferably calcium oxide from organic coral
• 1 gallon soluble potash (0-0-45), if needed, based on soil testing

Scheppele said it does not matter greatly what type of crop residue is on the fields because increasing the micro-organism activity will help to retain any nutrients in the soil, no matter the source.

He further explained the purpose of the different components in the nutrient recycling program:

• Ammonium thiosulfate (12-0-0-26) is a huge food source for microbes. Sugar or molasses are a food source for bacteria to multiply very rapidly. Fish protein contains oil that feeds the fungus, as well as good nutrient broth and bacteria that feed the soil and promote microbes.
  
  It is made from deep-sea fresh cod and the waste when fish is processed. Scheppele recommended the dry form for longer shelf life and ease of use.
  
  
• Bio-stimulants increase productive bacteria and fungi. It takes bacteria to break down the pithy insides of the cornstalk and corn cob and fungi to break down the really tough rinds on the stalk and the outside of the corn cob.
  
  
• Humates are forms of carbon. They are naturally occurring materials that constitute very rich humus. Humus is the organic component of soil, and it is formed by the decomposition of leaves and other plant material by soil micro-organisms. Carbon is a huge microbe food source.
  
  
• Calcium stabilizes N and creates an environment for microbial life to flourish.

Scheppele recommended conducting Haney soil testing, which measures what he said are the four most important things going on with soil: carbon levels (reflects energy/food source that drives soil microbes), CO2 levels (measures the amount of CO2 naturally released from the soil due to activity of soil microbes), organic nitrogen and the organic carbon-to-nitrogen ratio. (Incorrect ratios will affect how much nitrogen is available to plants.)

The CO2 levels, organic carbon, organic N and the carbon-to-nitrogen ratio are used to determine the soil health calculation number. Keeping track of this number annually allows farmers to gauge the effects of their management practices over time.

Scheppele recommended testing in the summer but said to avoid taking samples during times of drought or right after a heavy rain.

Scheppele said he has seen organic producers struggle with carbon-to-nitrogen ratios because of the limitations of what they can apply to their soils and recommended they also conduct Haney testing.

“Using the Haney testing really allows us to better understand carbon in the soil,” he said. “In the past, tillage practices released carbon from the soil; we know now microbes help to put it back. We need the optimal carbon-to-nitrogen ratios so plants can best utilize the nitrogen present in soil.”

Scheppele pointed out that nature will give more back to the soil than it takes for plants to grow, but operators and farmers need to be good land stewards and make sure the soil has the right micro-organisms to do that.

“If your soil program doesn’t currently monitor carbon levels, you should change programs,” Scheppele said. “Everyone should ask themselves if they are leaving the soil better than they found it.”  PD

Kelli Boylen is a freelance writer based in Waterville, Iowa.