wheat field2

When wheat harvest finishes up, baling or burning the wheat stubble has been the go-to way for producers to care for their land.  Burning is typically chosen over baling to manage pests like plant diseases or weeds and to improve the seedbed for the following crop; however, baling provides additional income.  In an article from Farms.com, they list things to consider before baling or burning wheat residue.  There are four factors to consider.

Loss of nutrients:  The products of burned wheat stubble are gases and ash.  Nutrients like nitrogen (N) and sulfur (S) are combustion products; phosphorus (P) and potassium (K) are in the ash.  When the residue is burned, one-third to one-half of the nitrogen and sulfur will combust.  The nutrients in the ash can go on for use by the plants.  Instead of dragging these important plant nutrients back into the soil, they can become air pollutants when the residue is burned. 

Amounts of nutrients remaining in wheat stubble (assuming 50 bu/ac yield):


graph2

Protection from soil erosion:  Bare soil is subject to water and wind erosion.

Water erosion:  Without residue, the soil can receive the impact of rain plus increasing the amount of soil particles that become removed during rainfall.  Bare, tilled soils can lose up to 30 tons per acre topsoil annually.  In no-till systems where residue is left, annual soil losses are often less than 1 ton per acre.  Crusting of the soil surfaces is caused by the detachment of soil particles which can also add to more amounts of sediment-laden runoff and reduce water infiltration and drier soils.  Leaving residue on the field raises surface roughness, that lowers the risk of both wind and water erosion. 

Wind erosion:  Standing stubble is more competent at preventing wind erosion than flat stubble.  Sometimes accident residue burns can result in destructive wind erosion events that happen repeatedly until a new ground cover is set.  When wind erosion occurs on a field it is difficult to control it.  Not even emergency tillage will help stop the erosion especially in drought conditions. 

Moisture infiltration rates and conservation:  Wheat residue boosts soil moisture by raising rainfall infiltration into the soil and reducing evaporation.  Residues protect the soil surface and keep it responsive to water movement into and through the soil surface.  Without protection, water and soil will run off the surface quickly. 

Soil quality concerns:   Repetitive burning of a cropland could very well lead to corrupt soil organic matter levels.  If the residue is continually burnt, soil organic matter won’t be allowed to rebuild.  Soil organic matter is helpful for plant growth as it adds the water holding capacity. 

Whether producers choose to burn or harvest their wheat stubble, timing is everything.  The best time would be to burn it right before the next crop is planted to minimize the time that the field could be exposed to erosion. Producers should also make sure to check with the USDA Natural Resources Conservation Service and/or the Farm Service Agency to find out if this will affect their compliance in any conservation programs.  


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