Timing and depth for fall fertilizer

September 28, 2016 - Issue 27

Fall fertilizer is best applied as close to freeze up as possible to balance two objectives: (1) allow soil to seal over the band and (2) reduce losses due to high microbial activity in warm soils.

Banding in wet soil conditions will increase ruts, and wet soils can also increase losses if the soil does not close well over the band. Good soil closure around the band can also be a challenge in dry soils.

Depth: Band urea at least 2” deep. For NH3 banding depth, Manitoba Agriculture soil fertility specialist John Heard recommends increasing the depth of the band if you are seeing a lot of gas or if you can still smell the gas strongly after applying it.

Adding phosphorus: If fields are short of phosphorus, consider a phosphate and urea blend. Work from Don Flaten at the University of Manitoba shows that phosphate and urea in a dual band applied in the fall can make phosphorus more readily available in the spring. The same concept does not necessarily apply in the spring where a dual band of urea and phosphate can actually delay uptake of phosphate. With fall application of phosphate, remember to save some phosphate to apply with the seed in the spring.

Further reading:

How to reduce fall N fertilizer loss

Canola Watch