Our Deep Banding project concludes this season.
When we started this project, yield trends were improving with the adoption of better genetics and agronomic practices. The downside was that soils were turning up deficient of nutrients in critical periods. Our hypothesis was that immobile nutrients were accumulating near the surface of the soil. We attributed this to the increased adoption of zero tillage and shallow banding.
We compared the results of periodic deep banding of immobile nutrients to annual shallow banding. By investigating the economical & agronomical viability of these practices, we can identify solutions to achieve potential yields and an increased return on investments.
We found that long-term, direct seeding and no-tillage practices can lead to nutrients settling in layers or bands near the soil's surface. These nutrients are relatively immobile nutrients such as phosphorus and nitrogen.
As farmers move to no-till practices, crop residue is left in the soil surface rather than being incorporated into soils. This non-uniform distribution of nutrients reduces the ability of crops to access soil nutrients.
The lack of tilling leaves crop stubble and weeds to die. The resulting plant decomposition further increases the nutrient accumulation at the surface.
Digging into deep banding
"Some immobile nutrients such as phosphorus may not become available to the crops in their root zones," says Farming Smarter Soil Research Scientist Gurbir Dhillon, Ph.D.
"Deep placement of fertilizers in the moist part of the root zone can help with nutrient availability under dry conditions."
In deep banding, using a shank opener to access the roots, fertilizer is placed 5-6 inches into the soil. We did not see any evidence of seedling mortality or lower crop emergence with the seed rows placed directly over deep banded fertilizers during our project.
Deep banding may cause higher mechanical disturbance of soil, which may lead to soil erosion of a loss of soil moisture. However, periodic deep banding (ideally once in three years) can lower labour costs and the potential for soil erosion while helping with nutrient distribution.
In our study, we compared a one-time deep banding at 5≥6-inch depth with annual shallow banding at a 2-inch depth. The deep banding was three times the recommended rate of phosphorus, nitrogen, and copper in the first year of the trial. The shallow banding was the recommended rate of fertilizers at seeding every year.
We did not find a consistent difference between the deep and shallow banded treatments for their effect on soils or crop yield. The results of this study indicate that the choice between these methods may come to the logistics.
Deep banding can help counter nutrient stratification by distributing them closer to the crop's root zone. Periodic deep banding, once every three years, also has an added convenience factor that can save farmers time and input costs.
Learn more about the project
To read more about this project, visit the Deep Banding Immobile Nutrients project page.
Catch a project Plot Shot:
Deep Banding Nutrients Plot Shot - May 27, 2020
Deep Banding Plot Shot - Sept. 20, 2020
or one of Ken Coles' presentations on the project:
Deep Banding Immoble Nutrients: Ken Coles and Dr. Tom Jensen - June 7, 2018
Deep Banding Immobile Nutrients