Crop Residue for Water Conservation

Mitiku Mamo is a Water and Integrated Cropping Systems Extension Educator serving Cedar, Dixon, Knox, and Wayne Counties. 

Crop residues are stalks, straw, leaves and other plant material that are left on the land after the crops have been harvested. Although it is impossible to put a dollar amount on the value of crop residues, unless residues are baled and sold, their benefits for the success of crop production are numerous. With harvest in progress, it is timely for producers to make decisions about how to effectively utilize crop residues.

The most important function of crop residues is protecting soil from wind and water erosion. Soil erosion by water occurs when rain drop impact breaks soil aggregates causing soil detachment and displacement from the soil surface. Once dislodged, soil particles will be readily available to be transported away from the site of the impact by runoff water or wind. Wind and rainstorms remove topsoil that is high in organic matter and nutrients. This will result in surface soil depleted of plant-available nutrients with low infiltration and low water holding capacity. Once left the field, the sediment and nutrient laden runoff water flows into nearby ponds, streams, and lakes where it becomes a water quality problem.

Availability of water is one of the limiting factors for dryland crop production. In Nebraska, we receive some percentage of our yearly precipitation in the form of snow. Storing as much of the snow precipitation as possible, in the soil, so that it can be available for the summer crops is very important. Keeping crop residues upright play a critical role in trapping and keeping more of the snow in the field. In addition to trapping snow, residues create a more uniform snow distribution resulting in a more uniform water distribution, slower surface water movement, and increased water recharge. On soybean or corn fields that have crop residues removed, snow just blows off the field and accumulates as large drifts on slopes and bottomlands where it stays longer during spring causing delays in field activities.

Crop residue also contains significant amount of nutrients. When residue decomposes, nutrients are released to be available for the next crop resulting in reduced use of synthetic fertilizer. Considering current fertilizer prices, it is an opportunity for farmers to reevaluate the practice of removing crop residue.

It may be tempting for producers to bale wheat straw and corn stalks, especially in years when livestock feed or bedding is in short supply. However, producers should weigh all the benefits of leaving crop residue in its place against baling. This is especially important for producers that farm dryland grounds.