Agronomy Ag Fundamentals

Recommended Maximum Fertilizer Rates

• The best position for P, up to the maximum levels shown above, is in the seed row as early availability (first 3 to 4 weeks) of P is critical to maximize plant health and yield potential.
• Approximately 30% to 40% of P used by the plant comes from P placed with seed in the same crop growing year. The remaining 60% to 70% comes from existing levels usually applied in previous years.
• Mustard, flax and peas are sensitive to salt effect from P (phosphate) fertilizer which can delay emergence, reduce seedling populations and delay crop maturity. Consider using the phosphate application rate flexibility provided by cereal crops grown as a part your crop rotation for managing P rates for sensitive crops. Placing higher rates of P with cereals allows for lower rates to be placed with sensitive crops.
• It is not recommended to place the P in the nitrogen band since the toxic band created by the N will prevent the roots from accessing the P until the N has diffused sufficiently, which may be after the 3 to 4 week early season critical period for P uptake by the crop.

• N content of sulfur fertilizer is generally the most important factor when considering the amount of sulfur. Mid row placement is recommended to prevent emergence delays, a reduction in seedling populations and maturity delays.
• Sulfur is highly mobile in the soil so mid-row placement is recommended.

• K is most efficient with the seed, second best is mid row, and worst placement is broadcast.
• The negative salt effect on seed with rates greater than 15 #/ac. (17 kg/ha) of K can produce emergence delays, reduced seedling populations and maturity delays.
• If more than the safe maximums of K are called for, recommended practice is to mid row band additional K.

• Minimum separation of 2 to 3” (50 to 75mm) between the seed and N is required to prevent potential seed burn.
• A good understanding of the nitrification process is important for all one-pass seeding producers, as it is key to the decisions made in placing nitrogen fertilizer in a single pass.
• Because nitrogen is highly mobile in the nitrate form (after conversion from ammonia and ammonium), mid row banding is very effective and is recommended.