With the early harvest and potential product discounts, producers may be considering fall fertilization soon.  I can appreciate the reasons for it such as the product discounts, covering acres, and the fact that we don’t know what spring weather will bring in order to fertilize before planting.

At the same time applying nitrogen when a growing crop is not present allows for nutrient loss and we continue to see nitrates in groundwater increase in some areas.  Check out the following Webcasts regarding research from UNL Soil Fertility Specialists as you consider nutrient application and the addition of nitrogen inhibitors.

Guidelines for Fall Fertilizing

If you do apply fertilizer in the fall, the Natural Resources District (NRD’s) have provided guidelines so please check specifically with them.  Both UBBNRD and LBNRD have said no fall fertilization before November 1^st and recommend no fall fertilization when soil temperatures are above 50°F.  This is because the conversion of anhydrous ammonia is much slower once soil temperatures are consistently below 50°F.  Please see the CropWatch Soil Temperature page for a map of current soil temperatures.

LBNRD also recommends but doesn’t require a nitrogen inhibitor placed with the anhydrous in the fall.  No liquid or dry nitrogen fertilizer can be applied between November 1st and March 1st without receiving a fertilizer permit.  With the fertilizer permit, producers will be required to put a nitrogen inhibitor in with their dry or liquid fertilizer.

Two exemptions are provided in the spreading of manure, sewage, and other by-products conducted in compliance with state laws and regulations, and the applications of pre-plant starter nitrogen to fall seeded crops, such as wheat.

A few other considerations from UNL Soil Fertility Specialists:

• Take soil samples as soil nitrates may be higher than normal this fall-particularly in dryland fields.
• Dry soils are difficult to sample and may affect results. Soil organic matter and soil nitrate results should be fine, but some soil pH and potassium may be affected by the dry conditions.
• Knife applications, including sealing of anhydrous ammonia injection tracks, also may be more difficult in dry soil conditions.
• Monitor rain and snow infiltration between now and the next growing season and make fertilizer adjustments next spring if excessive rain may have caused leaching.

Additional Resources

• Guidelines for Soil Sampling
• Nutrient Management for Agronomic Crops in Nebraska
• Soil Testing Critical After a Drought Year