N AND P FERTILITY FOR FLAX PRODUCTION

The current NDSU recommendation for the nitrogen (N) requirement of flax is three pounds N/bushel of seed yield. However, N levels, along with plant populations, need to be conservative because of potential for plant lodging and subsequent yield loss. Use of recommended N rates may increase lodging potential, especially in areas of fields with higher salt content. If a grower knows the salt-affected locations in a field, avoid these areas during N application and keep levels of N modest in the rest of the field. Also, don’t exceed planting rates to establish about 75 plants/square foot. This strategy will help maximize yield potential while minimizing risk of lodging.

Phosphorus (P) fertilizer use is important if soil test levels are low or very low. Broadcast application is best if the seeder is not equipped to separate seed and fertilizer by at least an inch.

Generally, no fertilizer is recommended with the seed. If the purpose of the fertilizer application is to make a profitable application, then broadcast or band apply . If a grower accepts the risk of stand reduction, then apply a maximum of 10 lb N/acre if applying N and seed in a one-inch spread.

Refer to the NDSU Extension Service circular SF-717 “Fertilizing Flax” for details.

ZINC FERTILITY NEEDS OF FLAX

Flax is susceptible to soils deficient in zinc. Situations conducive to zinc deficiency include soils with very low or low zinc test levels, low organic matter content, high ph, and coarse textures. Zinc deficiency is more pronounced when soil temperatures remain cool (less than 60 degrees) and soil zinc levels are low. Banded phosphorus application also may contribute to the condition.

Zinc deficiency symptoms in flax usually appear in patches in the field. The symptoms include young leaf chlorosis (older leaves not affected), plant stunting, and growing point suppression or death. If the growing point is affected, axillary buds develop to form many branches. This in turn will delay crop maturity. Zinc deficiency will reduce yield potential.

If the soil analysis indicates a zinc deficiency, apply 10 pounds/ acre of actual zinc as a broadcast treatment or 3 pounds/acre in a band or as a foliar treatment. If a soil analysis is not available, apply zinc. Zinc sulfate, which contains 36 percent zinc, is a common fertilizer for soil application. Cost of zinc sulfate is about $0.40/ pound.

STARTER FERTILIZER FOR CORN

Starter fertilizer can be applied with the planter in a band at least one inch to the side and below the seed. A two-inch by two-inch placement is recommended. Under cool, wet conditions, starter fertilizer offers some advantage. Band or broadcast fertilizer application is recommended versus a "pop-up" application (placement of fertilizer directly with corn seed). If plans exist to apply "pop-up" fertilizer, do not exceed 5 to 10 pounds/acre of nitrogen and 10 pounds/acre of phosphorus.