3 Nutrients Make the Most Impact on Alfalfa
Plant nutrition, along with adequate heat and moisture, are key factors in maximizing alfalfa yield.
Because we can’t control heat and moisture, it’s important to impact crop yield where we can by
establishing a sound understanding of the soil nutrient levels.
Did you know plant nutrition can affect yield up to 60 percent? While all nutrients are important, alfalfa yield appears to be most responsive to these three macronutrients: potassium (K), phosphorus (P), and sulfur (S). Boron (B) is one of the 17 micronutrients essential for crop health.
Like anything, it’s hard to know where to go if you don’t know where you are. Soil and tissue tests are especially valuable in areas of suspected deficiency. Scout, sample, and plan throughout the summer months.
Let’s take a closer look at the role these nutrients play in plant development and health:
- Potassium While potassium has relatively little influence on improving stand establishment, yield and stand survival are highly dependent on an adequate potassium supply. When soil tests are in the medium range or below, potassium should be added to meet the needs of the seeding year crop including the companion crop. (Crop removal rates range 50-55 lbs/DM ton)
- Phosphorus Adequate soil phosphorus encourages root growth. Research confirms that at low to medium soil test levels, incorporated phosphorus is more than twice as efficient as top-dressed phosphorus. (Alfalfa Management Guide, www.agronomy.org/files/publications/alfalfa-managementguide.pdf). (Crop removal rate range 6 lbs/DM ton)
- Sulfur All forms of fertilizer are equally effective when surface-applied or incorporated, according to University of Wisconsin – Extension. Elemental sulfur, however, must be converted to sulfate-sulfur before plants can use it. This process is relatively slow, so sulfur should be worked into the soil well before the crop needs it.
- Boron Plants won’t grow without boron due to its role in forming and strengthening cell walls. Low boron levels lead to poor growth of fast growing tissues and plant development. Boron is vital during periods of rapid growth, so it’s important plants can access boron during reproductive stages. Because boron is not easily transported within the plants, it should be available continuously for uptake by the roots. (Crop removal rate range is .08 lbs/DM ton).
Consider applying a test strip of some micronutrients. The information gathered will be relevant to you, as it is done on your farm, your acres, your weather and climate. As always, feel free to contact me if I may be of assistance as you set up on-farm tests. I may be reached at email@example.com or (715) 821-6654.