Is starter phosphorus necessary for silage corn in manured soils of the Fraser Valley?
Introduction
This research studied how different rates of mineral starter P fertilizer (0, 5, 10, 15, 20 kg P/ha) affect silage corn dry matter (DM) yield, plant P uptake, root growth, and available soil P during the growing season. These five application rates were chosen based on previous research that found starter P application rates typically used by farmers in this region (30-40 kg P/ha) could be reduced without negatively affecting yield.
In some regions of BC, the amount of P in agricultural soils has reached levels that are concerning for the environment.Surveys have found that many of British Columbia’s (BC)agricultural soils are considered to have “high” to “excess”levels of P – meaning that there is more than the amount needed for crop growth. When crops don’t use all this extraP during the growing season, it can wash away through surface runoff into nearby water bodies, causing harmful algal blooms that affect both human and aquatic life.
In BC’s Fraser Valley, silage corn is typically managed byapplying dairy manure at a rate that provides 50 kg P/ha at the beginning of the growing season (at plowing) plus 40 kgP/ha of mineral starter P fertilizer at the time of corn seeding. The mineral P fertilizer applied at seeding is called starter fertilizer and is intended to increase the amount of P available for early plant growth.
Because agricultural soils in this area are already high in P and manure is added every year (supplying more P) we wanted to see if mineral starter P fertilizer application rates could be reduced without negatively affecting yield or early plant growth.
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About this Brief
This brief was prepared by the BC Food Web team, and is based on the following scientific journal article:
Nyamaizi, S., Messiga, A. J., Cornelis, J.-T., Smukler, S. M., & Cade-Menun, B. J. (2024). Mineral phosphorusfertilization for silage corn in manured soils in the Fraser Valley, Canada. Agronomy Journal, 116, 362–379. https://doi.org/10.1002/agj2.21517
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Key Findings
- Applying starter phosphorus (P) fertilizer at rates between 5 to 20 kg P/ha* did not increase yield or early growth of silage corn compared to not using any starter P.
- This research was conducted on fields with soils that already have high P levels and where dairy manure is added every spring.