Arkansas: Furrow-Irrigated Rice Nitrogen Recommendations

Young rice crop. ©Debra L Ferguson Stock Photography

Nitrogen (N) management in furrow-irrigated rice (FIR), or row rice, systems has been evaluated over the past several growing seasons.  Currently, multiple options appear favorable depending on soil texture and field management considerations.  Below is some general guidance on N management strategies that have proven to be the most effective in trials conducted over the past several years.

Keep in mind the recommendations below are derived from work on hybrid rice.  When you see “preflood rate” we mean the rate you would normally apply prior to flood if you were flooding the field.  In most instances, based on our recommendations, that would be 120 lb N/acre on silt loam soils and 150 lb N/acre on clay soils.

It’s also important to note this work is conducted based on rotation with soybean.  If rotation differs, consult the 2021 Rice Management Guide (page 15) for adjusting the preflood N rate these recommendations are based on.

For silt loam soils, several N management strategies have appeared viable.

  • Option 1: Starting at the 5-leaf stage, apply 3 applications of 46 lb N/acre (100 lb urea/acre) spaced 7-10 days apart.
    • For example:
      • Day 0 – 46 lb N/acre
      • Day 7 – 46 lb N/acre
      • Day 14 – 46 lb N/acre
  • Option 2: Apply half the recommended preflood N rate at the 5-leaf stage, followed by 2 additional applications of one quarter of the preflood N rate spaced 7-10 days apart.
    • For example:
      • Day 0 – 60 lb N/acre
      • Day 7 – 30 lb N/acre
      • Day 14 – 30 lb N/acre
  • Option 3: An excessive preflood N rate (150% of standard) has produced optimal yields, but greater risk involved than split methods.

For clay soils, a single N management strategy has stood out:

  • Apply half the recommended preflood N rate at the 5-leaf stage, followed by half 10-14 days later, followed by an additional 46 lb N/acre (100 lb urea/acre) 7 days after the 2nd
    • For example:
      • Day 0 – 75 lb N/acre
      • Day 10-14 – 75 lb N/acre
      • Day 21 – 46 lb N/acre

For pureline varieties, at this time it is recommended to follow the approach of 4 applications of 46 lb N/acre (100 lb urea/acre) spaced 7-10 days apart beginning at the 5-leaf stage.  We hope to conduct future work to better identify optimal N management strategies for pureline varieties in FIR systems.

These strategies focus on early-season N management.  For hybrids, we still recommend the 30 lb N/acre (65 lb urea/acre) application at late boot in addition the early season N strategies discussed above.  For pureline varieties, the 4th application of 46 lb N/acre will coincide with the midseason timing and no additional applications should be needed.




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