Sorghum Tips

Hurricane Harvey – Considerations for Sorghum Fields Next Year

This tip was provided by:

Ronnie Schnell, Cropping Systems – Statewide, College Station,

Tony Provin, State Soil Chemist and Director – Soil Testing laboratory, College Station,

South and Central Texas

Hurricane Harvey – Considerations for Sorghum Fields Next Year

Many areas along the Texas Gulf coast were affected by devastating flooding and excessive rainfall during hurricane Harvey. Fields, especially near creeks and rivers, likely experienced significant flooding which may have resulted in soil erosion, soil deposition, residue accumulation and extended periods of saturation. On the brighter side, excellent grain sorghum yields were observed in many areas of south and central Texas. In AgriLife sorghum trials, 9 of 14 sites had hybrids yield greater than 7,000 lb/acre, many over 8,000 pounds. Good grain yield results in greater nutrient removal. These conditions will require some planning and management to ensure successful crops during 2018.

Soil Fertility

  • Surface runoff, leaching and gaseous loss of N were likely. The amount and distribution of residual soil N is uncertain.
  • A gradual decline in Texas soil sulfur levels have been observed over the past ten years.  The large recent leaching and runoff events likely removed most plant available sulfur potentially resulting in the need to apply modest amount of plant available sulfur for the next cropping season.
  • Erosion or deposition of soil can result in variation of soil phosphorus levels, as well as other nutrients.
  • Sorghum removes about 80 – 40 – 25 lb/acre (N-P2O5-K2O) for every 5,600 lbs of grain. That is equal to 50 lb/acre P2O5 and 31 lb/acre K2O for 7,000 lb/acre grain.
  • With all of the uncertainty surrounding current fertility conditions, as they say “don’t guess soil test”.

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Weed Control

  • Soil deposition and flood waters may have brought unwanted weed seeds to your field, including herbicide resistant weeds. A robust herbicide program should include pre- and post-emergence soil applied herbicides with scouting to apply other post emerge herbicides as needed.

Other Issues

  • Soil Compaction – harvesting on wet soils, flooding and saturation all could contribute to compaction issues. Strategic tillage of dry soils can be employed to alleviate compaction.  Take note of compaction issues as you soil sample.  A shovel or soil probe shouldn’t have to be hammered into the soil.
  • Residue Accumulation – normal residue levels will decompose as usual. Excessive accumulation of residue will require dispersal, reduction of particle size and incorporation to aid decomposition.  Pay particular attention to soil/mud entrained residue accumulations.  Due to limited aeration, muddy residues decompose at a very slow rate compared to normal.