Phosphorus Strategies

01:20AM Oct 23, 2013
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Your phosphorus management plan depends on where and how you farm, varying from field to field and soil type to soil type. Farm Journal Field Agronomist Ken Ferrie shares management tips for several examples:

Farming in the southern U.S.; planting into warm soil; high soil phosphorus levels; no fixation or tie-up issues: Broadcasting phosphorus at crop removal rates will probably work fine. A planting-time phosphate fertilizer application won’t likely show a yield response. 

Farming in the northern U.S.; high soil phosphorus levels; no fixation issues; 50°F soil: Apply phosphorus fertilizer to carry the crop until the soil temperature reaches about 65°F. A small amount of phosphorus applied with the planter will provide a significant yield response, even though your soil test says you don’t need any.

Corn/soybean rotation in central Illinois; low soil test P level; no fixation issues: Broadcast phosphate fertilizer aggressively to raise the soil P level. Apply phosphorus in starter fertilizer to carry the crop until the soil test level is optimum.

Calcaric soil with phosphorus fixation occurring: Apply phosphorus in the spring with the planter. Banding it will keep P available early in the season. In this situation, 30 lb. of phosphorus per acre applied with the planter will outperform 120 lb. broadcast because of availability.

Continuous corn; lots of residue. To pay the carbon penalty, increase the rate of phosphate fertilizer at planting. If you have low soil phosphorus levels, keep the starter rate high and broadcast the rest of your application. If your soil is already above optimum
levels, apply phosphorus with your planter, but make no broadcast application.

Corn/soybean rotation in central Illinois; warm soil: This farmer might need to do nothing more than broadcast phosphate fertilizer every two years. His job is much easier than others.

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The Nutrient Navigator series focuses on efficient, environmentally sound management of nutrients. The goal is to provide practical knowledge that helps drive yields and profits higher.