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Home > Protecting Our Lands & Waters > Best Management Practices > Nitrogen Fertilizer Best Management Practices

Nitrogen Fertilizer Best Management Practices


Supporting Documentation: Please note there is significant amount of documentation, references and corresponding research results that support the BMPs. This information is provided through a series of University of Minnesota Extension publications found on their Nitrogen Nutrient Management website.

  • Best Management Practices for Nitrogen Use in Minnesota
  • Best Management Practices for Nitrogen Use in Northwestern Minnesota
  • Best Management Practices for Nitrogen Use in South-Central Minnesota
  • Best Management Practices for Nitrogen Use in Southeastern Minnesota
  • Best Management Practices for Nitrogen Use in Southwestern and West-Central Minnesota
  • Best Management Practices for Nitrogen Use on Coarse Textured Soils
  • Best Management Practices for Nitrogen Use: Irrigated Potatoes

Southwestern and West-Central Minnesota

Recommended BMPs For Corn:

  • Select the appropriate N fertilizer rate using U of M guidelines ("Fertilizing Corn in Minnesota” FO-3790-C, 2006 (PDF) or newer) which are based on current fertilizer and corn prices, soil productivity, and economic risk.
  • Total N rate should include any N applied in a starter fertilizer, weed and feed program, and contributions from phosphorus fertilizers such as MAP and DAP.
  • Use a soil nitrate test when appropriate, by collecting soil samples to a depth of 24 inches in 0 to 6 and 6 to 24 inch increments. Collect fall soil samples after soil temperature at 6 inches stabilizes below 50°F.
  • For urea (46-0-0) or anhydrous ammonia (82-0-0) applied in the fall, delay application until after soil temperature at 6 inches stabilizes below 50°F.
  • Incorporate fall applied urea (46-0-0) as well as spring applied urea (46-0-0) and UAN (28-0-0) within 3 days to a minimum depth of 3 inches.
  • Take appropriate credit for previous legume crops and manure used in the rotation.
  • Under rain fed (non-irrigated) conditions, apply sidedress N before corn is 12 inches tall (V7 stage).
  • When soils have a high leaching potential (sandy texture) split application is preferred. Use a nitrification inhibitor with early sidedressed N applied to these soils.

Acceptable BMPs For Corn, But With Greater Risk:

  • Late fall or spring preplant application of ESN.
  • Use of products, Agrotain and N-Serve, with fall applied N.

Recommended BMPs For Sugarbeet Production:

  • Use a soil nitrate test by collecting soil samples to a depth of 4 feet after soil temperature at 6 inches stabilizes below 50°F.
  • Apply ammonium based fertilizer N in the fall according to U of M guidelines (110 to 130 lb. N per acre). The N rate is a total of NO3-N measured to a 4 foot depth plus fertilizer N.
  • Apply fertilizer N in the fall after soil temperatures at the 6 inch depth stabilize below 50°F.
  • Take first and second year credits for forage legumes that were part of the rotation.

Practices Not Recommended For Corn and Sugarbeet Production:

  • Fall application of UAN (28-0-0) or any fertilizer containing nitrate-nitrogen.
  • Shallow or no incorporation of urea (46-0-0) applied in the fall.
  • Fall application of any N fertilizer to coarse textured (sandy) soils.
  • Winter application of nitrogen fertilizers including MAP and DAP on frozen soils.

Northwestern Minnesota

Nitrogen management practices for small grain production are provided below. For corn and sugarbeets, refer to practices for Southwestern and West Central Minnesota. For management practices on sandy soils, refer to the section titled “Coarse-Textured Soils”.

Recommended BMPs For Small Grains:

  • Base rate of nitrogen applied on expected yield, with some general consideration of soil organic matter content and previous crop.
  • Total N rate should include all fertilizer sources including contributions from phosphate fertilizer such as DAP and MAP either broadcast or banded at planting.
  • For ammonium based products (AA or urea) apply when soil temperatures at 6 inches stabilize below 50°F.
  • Take credit for nitrogen supplied by previous legume crops in the rotation.
  • Take credit for available nitrogen supplied in manure or the nitrogen contained in sugarbeet tops based on leaf color prior to beet harvest.
  • Adjust the nitrogen rate for measured residual nitrate-nitrogen in the surface 2 feet of soil profile when wheat follows a non-legume crop in the rotation.
  • Collect soil samples in increments of 0 to 6 and 6 to 24 inch increments after soil temperature at 6 inches stabilizes below 50°F.
  • Any broadcast urea should be incorporated to a depth of 3 inches.

Acceptable BMPs For Small Grains, But With Greater Risk:

  • Limit rate to 40 lb. N per acre if a liquid source of nitrogen is applied to foliage at the boot stage or later.
  • Application of urea in a band either with the seed or near the seed when an air seeder is used for planting.

Practices Not Recommended:

  • Fall application of liquid nitrogen (28-0-0) or any fertilizer containing nitrate-nitrogen.
  • Fall or spring application of urea without incorporation.
  • Shallow (2 inches or less) application of 82-0-0 in either fall or spring.
  • Foliar application of high rates of 28-0-0 (more than 40 lb. N per acre) at boot stage or later.
  • Application of any N fertilizers including MAP or DAP on frozen soils.
  • Fall application of N, regardless of source, to sandy soils in the fall.

Southeastern Minnesota

Recommended BMPs For Corn:

  • Select an appropriate N fertilizer rate using U of M guidelines ("Fertilizing Corn in Minnesota” FO-3790-C, 2006 (PDF) or newer) which are based on current fertilizer and corn prices, soil productivity and economic risks.
  • Total N rate should include any N applied in a starter, weed and feed program, and contributions from phosphorus fertilizers such as MAP and DAP.
  • Spring preplant applications of ammonia and urea or split applications of ammonia, urea, and UAN are highly recommended.
  • Incorporate broadcast urea or preplant UAN within three days.
  • Under rain fall (non-irrigated) conditions, apply sidedress N before corn is 12 inches tall (V7 stage).
  • Inject or incorporate sidedress applications of urea or UAN into moist soil to a minimum depth of three inches.
  • Take appropriate credit for previous legume crops and any manure used in the rotation.
  • Minimize direct movement of surface water to sinkholes.
  • When soils have a high leaching potential (sandy texture), nitrogen application in a split-application or sidedress program is preferred. Use a nitrification inhibitor on labeled crops with early sidedressed N.

Acceptable BMPs For Corn, But With Greater Risk:

  • Spring preplant application of UAN (28-0-0).
  • Spring preplant application of ESN.

Practices Not Recommended:

  • Fall application of ammonia, urea, and UAN with or without a nitrification inhibitor (N-Serve).
  • Sidedressing all N when corn follows corn.
  • Fall application of N to coarse-textured (sandy) soils.
  • Application of any N fertilizer including MAP or DAP on frozen soils.

South-Central Minnesota

Recommended BMPs For Corn:

  • Select an appropriate N fertilizer rate using U of M guidelines ("Fertilizing Corn in Minnesota” FO-3790-C, 2006 (PDF) or newer) which are based on current fertilizer and corn prices, soil productivity and economic risks.
  • Total N rate should include any N applied in a starter, weed and feed program, and contributions from phosphorus fertilizers such as MAP and DAP.
  • Spring preplant applications of ammonia and urea or split applications of ammonia, urea, and UAN are highly recommended.
  • Incorporate broadcast urea or preplant UAN within three days to a minimum depth of 3 inches.
  • Inject or incorporate sidedress applications of urea or UAN into moist soil to a minimum depth of 3 inches.
  • Take appropriate credit for previous legume crops and any manure used in the rotation.
  • Under rain fed (non-irrigated) conditions, apply sidedress N before corn is 12 inches tall (V7 stage).
  • When soils have a high leaching potential (sandy texture), nitrogen application in a split-application or sidedress program is preferred. Use a nitrification inhibitor (N-Serve) on labeled crops with early sidedressed N.

Acceptable BMPs For Corn, But With Greater Risk:

  • Fall application of ammonia + N-Serve after soil temperature at the 6 inch depth is below 50°F.
  • Spring preplant application of UAN (28-0-0).
  • Late fall or spring preplant application of ESN.

Practices Not Recommended:

  • Fall application of urea and ammonia without N-Serve.
  • Sidedressing all N when corn follows corn.
  • Fall application of N to coarse-textured (sandy) soils.
  • Application of any N fertilizers, including MAP and DAP on frozen soils.
  • Fall application of UAN (28-0-0).

Coarse Textured Soils

Recommended BMPs For Corn and Edible Beans:

  • For corn, select an appropriate rate using U of M guidelines ("Fertilizing Corn in Minnesota” FO-3790-C, 2006 (PDF) or newer) which are based on current fertilizer and corn prices, soil productivity, and economic risk.
  • For edible beans, base N rate on expected yield and previous crop.
  • Total N rate used for corn and edible beans should include any N supplied in a starter, in a weed and feed program, and contributions from phosphate fertilizers such as MAP and DAP.
  • Use split applications of fertilizer N for both corn and edible beans.
  • Use a nitrogen stabilizer (N-Serve) on labeled crops when early sidedress N is used.
  • Take appropriate N credits for legumes and manure used in the crop rotation.
  • If possible, apply N fertilizers below the soil surface or incorporate with light tillage or irrigation.

Acceptable BMPs, But With Greater Risk:

  • Spring preplant application with a nitrification inhibitor (corn).
  • Single sidedress application of anhydrous ammonia or urea early in the growing season without a nitrification inhibitor.
  • Spring preplant application of ESN.

Practices Not Recommended:

  • Fall application of N regardless of source.
  • Disregard of N supplied by legumes in rotation or the application of manure.
  • Spring preplant N for corn without a nitrification inhibitor.
  • N fertilizer applied to corn (fertigation) after tasseling.
  • Application of ESN to edible beans after planting.

Irrigated Potatoes

General Recommended BMPs For Irrigated Potatoes:

  • Base N rate on variety, harvest date, and realistic yield goals.
  • Account for N from previous crops.
  • Test irrigation water for nitrate content and adjust N fertilizer accordingly.
  • Match N application with demand; plan the majority of soluble N inputs from 10 to 50 days after emergence; or apply ESN for mid to late season varieties no later than emergence.
  • Follow proven water management strategies to provide effective irrigation and minimize leaching.
  • Establish a cover crop following potatoes whenever possible.
  • Nitrogen applied through the hilling stage should be cultivated/incorporated into the hill.
  • Use petiole analysis to aid in making post-hilling N applications.

Practices Not Recommended:

  • Fall application on sandy soils (sands, loamy sands, and sandy loams).
  • Excessive rates of starter N (more than 40 lbs. N/A) for mid/late season varieties.
  • Excessive rates of starter N (more than 60 lbs. N/A) for early harvested varieties.
  • Use of starter fertilizers containing nitrate.
  • ESN for early harvested potatoes (vines killed or green dug before August 1).

Specific BMPs for Mid to Late Season Varieties (Vines killed or green dug August 1 or later)

Option 1 – when fertigation is available:

  • Apply up to 40 lb. N/A in the starter (this amount should be included in meeting the total recommended N rate).
  • Apply one-third to one-half of the recommended N at or around emergence and cultivate/incorporate the fertilizer into the hill; if ESN is used, apply no later than emergence and incorporate in the hill.
  • If hilling at emergence is the final hilling operation, begin fertigation 14-21 days later and apply the remainder of the recommended N in increments not exceeding 40 lb. N/A.
  • If a final hilling operation is done 10-14 days after emergence, apply one-third of the recommended N at that time and cultivate/incorporate the fertilizer into the hill. On heavier textured soils during rainy periods, it may not be possible to time this application properly due to row closure; in this situation, the N can be applied using fertigation.
  • Base timing of subsequent N applications on petiole analysis; apply up to 40 lb. N/A per application through the irrigation system.
  • Establish a cover crop after harvest whenever possible.

Option 2 – for mid/late season varieties when fertigation is not available:

  • Apply up to 40 lb. N/A in the starter (this amount should be included in meeting the total recommended N rate).
  • Apply one-third to one-half of the recommended N at or around emergence and cultivation/incorporate the fertilizer into the hill; if ESN is used, apply no later than emergence and incorporate in the hill.
  • Apply the remainder of the recommended N rate at final hilling and cultivate/incorporate the fertilizer into the hill.
  • Establish a cover crop harvest whenever possible.

Specific Practices for Early Season Varieties (Vines killed or green dug before August 1)

  • Apply up to 60 lb. N/A in the starter (this amount should be included in meeting the total recommended N rate)
  • Apply one-third to two-thirds of the recommended N at or around emergence and cultivate/incorporate the fertilizer into the hill
  • Apply the remainder of the recommended N rate at final hilling and cultivate/incorporate the fertilizer into the hill
  • If fertigation is available, base timing of subsequent N application on petiole analysis; if needed, apply up to 30 lb. N/A per application through the irrigation system; avoid late applications of N, because that will delay maturity.
  • Establish a cover crop after harvest.

MDA Contact

Bruce Montgomery, Unit Supervisor
Fertilizer Management Unit
Bruce.Montgomery@state.mn.us
651-201-6178
Pesticide & Fertilizer Management Division