When switching to continuous no-till soil undergoes a profound change. It changes from being constantly disturbed to a stable state. The biology in soil (microbes, worms, fungi, etc.), not to mention the physical structure of soil, take time to adapt to this change. As with most transitions in life, this doesn’t happen overnight, but over time the change produces substantial positive benefits, that producers agree are worth the wait.
The important concept to remember is that the lands on which producers use to grow our food is part of a natural system that has been thrown into an unnatural situation. By incorporating cover crops into a continuous no-till system a producer can begin to mimic the natural system that has thrived for millennia here on Earth.
Initially in the transition, producers may lose some yield from their fields, between 5 and 10 percent. This yield loss can come in part from a loss of oxygen to the soil (which stimulates bacteria and microbes to break down organic matter and release nutrients to plants). However, over time soil health begins to improve as the biologic life in soil stabilizes and nutrients are restored to the soil. At this time, competition for nitrogen also occurs due to the increase in soil productivity, and more nitrogen is stored in soil in the form of organic matter and humus.
By adding cover crops to the system we can see an increase in nitrogen cycling, reduced erosion, improved phosphorus retention, stabilized soil temperatures, reduced compaction, and improved water infiltration, among other things.
Leguminous cover crops fix nitrogen to reduce the need for nitrogen fertilizer. In fact these cover crops can add up to a credit of 150 pounds/acre of nitrogen to the field in good growing years. Non-legumes can recycle the nitrogen that may have been leftover from the previous crops and bring it into the zone where plants can utilize it in the next season. Furthermore, the nitrogen utilized by the cover crop is not leached further into our waters, this helps to minimize problems like eutrophication and hypoxia throughout the Great Lakes Region.
In systems that don’t utilize cover crops erosion tends to be greater and therefore the possibility of losing phosphorus also increases. Phosphorus attaches to clay particles and with any rainfall event where soil is exposed, soil particles along with phosphorus are lost to waterways. Contrastingly, by utilizing cover crops the soil is covered in rain events and significantly less clay particles are removed from the field into a given water source. In turn, the producer saves money (less fertilizer needs to be purchased because more is left in the field).
Many producers like to open their fields up in the spring by running a cultivator or other tillage implement over their fields to allow the soil temperature to rise and dry out to allow for earlier planting. This practice does make sense but producers who have done long-term no-till with cover crops have found it is unnecessary because their soils are warm early too because of cover crops.
Cover crops act as a thermostat for the soil. They help to regulate soil temperature by keeping the soil warmer in colder weather and cooler in extreme heat. When transitioning to no-till, soils are often wet and cold. It is difficult for wet soil to warm up because minimal pathways exist for air to filter through the soil allowing it to dry out and warm up. However, cover crops’ roots create channels that allow water and air to move through soils which ultimately allows cold water to filter out of soils and air to move through soil, drying out soils and increasing soil temperatures. Additionally, cover crops help to heat the soil by increasing the organic matter content. Over time, this addition of organic matter changes soils that were light brown to brown to dark brown and black. The dark brown/black residue absorbs sunlight and ultimately helps to warm the soil. Furthermore, this newly formed organic matter is full of life, and the living organisms produce heat, also contributing to the warming of the soil.
Compaction issues are a common problem in tillage systems. However, there are numerous ways to overcome this potential concern. By switching to no-till with continuous cover crops soil organisms (plants and fungi) have the chance to begin forming glomalin, created from the production of plant root sugars and proteins from fungi, that help to form micro and macro- aggregates. These aggregates leads to stable, productive soil structure that allow roots to move through soils and have access to water and air channels that are crucial for maximum plant growth and breaking up hardpans in soil. This crucial relationship between plants and fungi are a large part of the long term solution to compaction issues that plague producers. Utilizing GPS programs to minimize trips across the field with heavy machinery also prove successful in mitigating and reducing compaction.
Cover crops in a no-till system or any system will also improve water holding capacity and increase infiltration. One pound of soil organic matter can hold 18 to 20 pounds of water. Tilled bare soils can hold 1.5 to 1.7 inches of water but soils with continuous vegetation can hold 4.2 to 4.5 inches of water. In the recent drought year of 2012, producers that had cover crops had crop yields that far exceeded their competitors who had bare tilled soil. In an NRCS survey of producers in the hardest hit drought regions of the Corn Belt, those who used cover crops the previous season and/or seasons before had yields 11 percent higher on average than their counterparts who did not use cover crops and a 14.3 percent higher yield on average for soybeans. As one survey respondent said, “Soil health is key. Cover crops are better than steel.”
Converting to no-till has it challenges, but it is obvious that by utilizing cover crops in the process the transition can be eased, hopefully with minimal losses of yield or none at all. By combining cover crops with no-till, the maximum benefits of higher yields over time, reduced nutrient loss, less erosion, greater water infiltration and holding capacity, higher organic matter content, moderated soil temperatures, and reduced pest pressure from weeds, diseases, and insects by means of greater biological diversity can be realized.
If you have questions about converting to no-till or cover crops and potential cost-share funding to help offset the conversion cost please contact the Gratiot Conservation District and NRCS at the Ithaca Service Center or call (989) 875-3900 x 3.
Information taken from the USDA-NRCS Michigan Technical Note: Using Cover Crops to Convert to No-Till: June 2010 and the 2012-2013 Cover Crop Survey in cooperation with the North Central SARE and the Conservation Technology Information Center
Words of advice for starting to use cover crops in any system:
- Start small. Start on a small amount of acres to help reduce risk.
- Choose wisely. Select cover crops that are easy to grow and kill, productive, and priced moderately.
- Plan ahead. Consider your rotation and how you will manage your cover crop.
- Don’t skimp. Follow your plan, plant on time and at the correct rates. Consider another option in case problems arise.
- Stay sharp. Make sure your implements are ready to handle the system (like your planter).
- Be creative. Keep an open mind and don’t be afraid to experiment and/or ask for help.