by Ethan Thies
Conservation of our farmland, much like our management of the crops we grow on it, is a journey of constant improvement. As we plan to manage our soybean acres to increase yields year after year, we should include in those plans ways to better protect our soil and water.
Stacking practices
Research has shown that stacking multiple conservation practices within a field can significantly reduce sediment and nutrient losses. Keeping sediment and nutrients in soybean fields, where they can be used for crops, is the key to sustainable soybean production into the future. It’s what makes us stewards of our lands and waters.
Stacking conservation practices on fields incorporates both in-field and edge-of-field conservation practices into your conservation planning.
In-field conservation practices are management practices implemented yearly on cropland acres. Reducing tillage and planting cover crops are the two most common in-field conservation practices incorporated into soybean production. Reducing tillage in crop rotations keeps crop residue on the surface to protect the soil and maintains soil structure. Fields that infiltrate more water and have better soil structure have a reduced risk of erosion during heavy rainfall.
When planning for soybean production, consider reducing tillage both before planting and after harvest. Soybean residue has a lower carbon-to-nitrogen ratio than cornstalks and therefore will break down more quickly. Even light tillage will speed up the breakdown of soybean residue, reducing the amount of time it provides surface protection to the soil.
When harvesting corn before soybeans, leaving stalks standing rather than chopping or tilling can help reduce wind and water erosion. It also helps keep snowfall in the field over the winter. No-till or strip till are the best ways to keep soil surface residue and maintain soil structure.
Cover crops are a do-it-all conservation practice that protects the soil from wind and water erosion, as well as holding nitrogen that might be lost to subsurface water flow. Seeding a winter hardy cover crop, such as cereal rye, the fall before you plant soybeans is an easy way to start using cover crops.
Those new to implementing cover crops should plan to terminate cereal rye in the spring when it is 6 to 10 inches tall, or 10 days before planting. Following soybeans and ahead of corn, beginning cover croppers may want to consider using oats to reduce concerns of nitrogen tie-up and disease in the spring.
Cover crops pair well with no-till practices and together fulfill the soil health principles of:
- covering soils
- reducing disturbance
- keeping living roots in the soil
- increasing biodiversity
Long-term users of cover crops and no-till may see additional soil health benefits along with the conservation benefits of these practices.
Edge-of-field practices
Soybean growers should consider utilizing edge-of-field conservation practices to complement in-field management practices to further reduce soil and nutrient losses.
Edge-of-field practices such as terraces and waterways have been used for decades. However, there are some newer practices making their way onto farm landscape across the state to further address sediment and nitrate loss.
Prairie strips are a versatile practice to reduce soil erosion. They use native grasses and forbs to create strips of habitat that reduce erosion.
For tiled fields, bioreactors and saturated buffers utilize biological processes to reduce nitrate loss from tile lines. Saturated buffers can be installed into new or existing buffers along streams and divert the tile flow into the soil underneath a vegetated buffer, where it outlets into the stream. Bioreactors are more versatile in their placement, routing tile water through woodchips to treat tile water.
As equipment size changes on our farms, changes to some edge-of-field practices installed in the past may be required. Precision technology can make designing or relocating edge-of-field practices work well with field operations.
When considering removing older edge-of-field practices that no longer fit your operation, it is important to investigate incorporating other practices to continue to provide the same or greater conservation benefits.
Where to start
Conservation professionals across Iowa can help soybean growers implement conservation practices on their fields. Local USDA offices are a valuable starting point to talk with the Natural Resources Conservation Service and partner staff, who can help plan conservation practices and connect you with cost-share programs.
Many co-ops have conservation agronomists on staff who can help you incorporate practices into your crop management system. Iowa State University’s field agronomists and natural resources Extension teams are also available to answer questions.
I can be reached by phone at 319-350-7871 or email at ethies@iastate.edu to help connect you with resources for the conservation practices you’re interested in.
Thies is an Iowa State University Extension conservation fields specialist.