The acreage of flax is on the rebound. Flax has its own unique challenges with regards to production and nutritional requirements. Much of the fertility work on flax has been conducted in North Dakota and Canada. Flax has a requirement for nitrogen. N needed From the result, subtract the soil test nitrate level.
Placement is important.
If the decision is made to band fertilizer with the seed, low rates are suggested, perhaps deferring the additional P recommended towards crops in the rotation that will respond better to it, such as small grains or corn. Banded phosphate is also associated with a greater frequency of zinc deficiency. No K fertilizer is recommended at K levels higher than 120 ppm. K levels lower than 120 ppm would usually only be found in coarser textured soils along the Red River Valley beach ridges, outwash plains or some of the older sediments west of the Missouri River Valley. Flax is sensitive to low soil zinc levels.