The Costs of Stubble Burning
Crop residue is an important component of soil health and the burning of straw ultimately costs the producer money. There are several benefits from leaving standing stubble in the field, including trapping snow, minimizing water and wind erosion, and returning valuable nutrients to the soil. Trapping snow during the winter months has several advantages in terms of enhancing the supply of moisture in the spring for the crop and in improving the survival of winter wheat crops.
Crop residue can be a very effective tool in preventing soil erosion. During heavy rain events, exposed soil is much more likely to be eroded away than soil that is protected by crop residue. The straw absorbs the impact of the rain and allows the water to infiltrate the soil rather than simply running off, carrying valuable topsoil with it.
Wind erosion is also greatly reduced by leaving crop residue on the field. Standing straw helps to slow wind speeds at ground level, protecting the topsoil from being blown away and trapping blowing soil.
Leaving straw in the field also returns nutrients valuable to crop growth back to the soil. These nutrients include carbon, nitrogen, phosphorus, potassium, sulfur, calcium and magnesium. When straw is burned, about 90% of these nutrients are lost (Heard et. al., 2001). As a result, the soil requires supplemental amounts of fertilizer to be productive, which costs the producer money.
Finally, by incorporating straw into the soil you are returning organic matter back into the soil. Organic matter from straw, stubble and chaff binds soil particles, improving soil structure. Well-structured soils drain faster and make better seedbeds. Most importantly, good soil structure improves the ability of the soil to deliver water and nutrients to crops.
The burning of crop residues has many short-term results, both for the public and the producer. However, we also need to be aware of the potential for long-term degradation of a valuable resource. With the many constraints and issues that producers face today it is easy to lose sight of the long-term impact of burning crop residue on soil health. We must always consider the long-term benefits of incorporating straw with respect to erosion protection and the maintenance of a viable, high quality resource.
Costs to the Soil from Stubble Burning
- Loss of organic matter.
- Increased potential for soil compaction.
- Greater potential for erosion (wind and water).
- Loss of valuable nutrients (carbon, nitrogen, phosphorous, potassium, sulphur, calcium and magnesium).
- Damage to soil structure (poor drainage and less efficient transfer of water and nutrients to the crop)
- Lower microbial activity.
See the Soil Management Guide for additional information.
