As regulations related to fertilizer application increase across the Midwest, many producers are evaluating the feasibility of applying fertilizers below the soil surface. Often, it is unclear which types of implements are best suited to meet the nutrient management goals set for your farm. Equipment capable of sub-surface placement can vary in horsepower requirements, placement options, and the level of tillage. To help identify which implement(s) is best suited for your farm, the Ohio State Precision Ag Team compiled a list of sub-surface placement benefits and categorized available equipment options. Here are several benefits of sub-surface placement of fertilizers:
• It makes fertilizers readily available for crop uptake.
• It can potentially reduce pre-plant field passes to a single operation, conserving fuel and reducing compaction.
• Strip-till, sub-surface placement equipment allows for optimal seedbed preparation, improving planter performance.
• It can reduce off-site transport of fertilizer in overland runoff.
For a decision aiding tool, we categorized currently available sub-surface placement implements into one of the four categories:
1. “Deep rip and placement” implements apply a fertilizer band (generally three to eight inches) of liquid, dry, or anhydrous, prior to the growing season and usually involve some type of tillage or seedbed modification. They are generally able to operate three- to six-miles per hour in a minimal till to strip-till environment.
2. “Zone mixing” type implements mix fertilizer and soil in a tilled zone generally around eight inches wide wide and six inches deep. Typically uses a multiple coulter setup to induce a thorough mixing action on the soil while blending liquid, or dry fertilizer or manure. Generally able to operate in the seven- to 12-miles per hour range in a strip-till or similar environment.
3.“Injection” type implements apply a shallow, narrow band of fertilizer (generally three to five inches), of liquid, dry, or anhydrous fertilizer. Typically, these implements use a single coulter or similar opener to inject the fertilizer product into a thin opening of the soil. These implements normally operate in the seven- to 12- miles per hour range in a no-till or minimal till environment.
4. Broadcast then Incorporate application is typically conducted by a dual spinner-disc spreader followed by incorporation through disc, field cultivator, or similar tillage tool. Incorporation can be done any time after the broadcast application, but preferably within three to five days.