‘Up in Smoke’¾Lost Opportunities When Stubble Is Burned

No-Till on the Plains, Inc. encourages producers to “learn not to burn” following this year’s wheat harvest.  Standing stubble is vital to a successful continuous no-till system.  By burning this valuable resource, producers put their soil and future profitability in peril.  Before putting a match to their stubble, producers should carefully consider the repercussions¾regardless of their tillage habits.

In monoculture wheat, burning has traditionally been thought useful to economically reduce levels of weed seeds and disease inoculum present in the straw.  However, viable crop rotations and no-till methods have proven their meddle across the region, and are much more effective at reducing weed and disease pressure in wheat.

During a fire, nearly all of the carbon, nitrogen (N), and sulfur (S) contained in the stubble will be lost to the atmosphere.  Ashes containing phosphorus (P) and potassium (K) can be blown from the field as well.  These are direct losses of nutrients from the land that must either be replaced or will result in reduced yields of future crops.  However, stubble kept on the soil surface will gradually decompose and release the nutrients to subsequent crops and to the microbes that sustain soil vitality.

By keeping the stubble on a field, soil moisture is increased dramatically, as shown repeatedly in experiments and by casual observation.  Moisture is a scarce resource on the High Plains, and preserving more moisture with stubble retention can substantially enhance crop yields.   

Stubble plays an important role by protecting the soil from raindrop impact, allowing the precipitation to infiltrate the natural soil pores. Studies show that infiltration is tightly correlated to the percentage of the soil surface covered by crop residues.  In continuous no-till soils, channels formed by roots and earthworms allow greater movement of water deeper into the soil. Earthworm populations increase tremendously under no-till conditions, and soil-dwelling fungi secrete substances to bind soil particles into a crumb structure that improves porosity.

Burning the stubble away produces a bare surface where raindrop impact breaks loose soil particles which then clog the soil pores, sealing the surface and causing the water to run off¾often with a producer’s topsoil along for the ride.  Loss of topsoil during a rain event may account for a measurable loss in crop yield in subsequent years.  

In a well-managed continuous no-till system, precipitation tends to stay where it falls. Reduced water movement means that every part of a field¾including slopes¾enjoys the benefits.  Once the water has soaked into the soil, the mulch at the surface reduces water loss from evaporation.  This is key during the hot summer months as the sun bakes the ground.  An adequate mulch of stubble can inhibit weed germination and will virtually eliminate wind erosion. 

With high fuel and fertilizer prices, many farmers are rethinking their production strategies.  Don’t let your resources go up in smoke.  Turn more moisture into grain with continuous no-till, and reap the financial rewards.  And for land’s sake, don’t let the soil go naked even if it is summer!

For more information on No-Till on the Plains, visit www.notill.org or call (888) 330-5142.  Additional information on this article’s topic is available in the free brochure Understanding the Process of Water Infiltration by world-renowned scientist/consultant Rolf Derpsch, published by No-Till on the Plains, Inc.