Moisture and temperature with conservation tillage
Reducing tillage is one approach used to build the benefits of a healthier soil — like reducing erosion and better water management. But, leaving some extra residue on the surface can be daunting in the Red River Valley, where soils are high in clay, can hold a lot of water and be slow to warm up in the spring.
Moisture and temperature conditions at planting are probably the primary concern of farmers exploring the idea of reducing tillage. We put a few conservation tillage practices to the test at the Soil Health and Agriculture Research Extension Farm in Mooreton, N.D.
In 2015, we set up field-scale plots at the SHARE Farm. We evaluated (1) shallow vertical tillage, (2) fall strip till with shanks, (3) spring strip till with coulters and (4) fall chisel plow with spring field cultivation in replicated strips on approximately 60 acres across the field. We also had 100 acres of no-till management across the field. Soil moisture and temperatures were measured in each tillage treatment using sensors placed in the soil for each replicated tillage treatment to take hundreds-of-thousands of measurements throughout the year. Stand counts, residue cover and yields also were measured for each of the tillage treatments.
What did we find? In each spring and early summer, the chisel plow and strip-till berms were the driest and warmest of the treatments. The residue covered areas between the strip-till berms, vertical till and no-till areas were the wettest and coolest soil conditions in the spring. That being said, observed differences in drying and warming conditions were minimal in the high clay soils of the SHARE Farm. Also, as the surface soils dry, moisture is readily replaced through the capillary rise of water deeper in the soil profile (meaning ground water is brought toward the surface by the tension in the tight pore spaces of a clay soil). Trends in soil moisture and temperature did not cause any differences in soybean and corn plant populations, growth or yields.
There are a few things that we need to keep in mind when reducing tillage in general.
The first is that residue needs to be managed out the back of the combine in a reduced till system. This is probably the most important part of the process to "get right" according to a majority of farmers using no-till successfully.
They will also tell you that replacing disk openers on equipment to keep them sharp for cutting through residue is also extremely important. Adjustments should be made not only to equipment but overall management approaches for diseases, weeds and pests — this is a system after all and reduced till is just one tool used in that system.
Lastly, remember that no yield loss with less inputs equals more profits. We don't need to have an increase in yield with reduced tillage to be making more money.
Research credits: Aaron Daigh, NDSU Soil Science, and Jodi DeJong-Hughes, University of Minnesota Extension.