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How Drought Affects Nutrients

 

How Drought Affects Nutrients

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When growers face suboptimal crop yields due to drought, a common question is how much fertilizer will be required for the next growing season.

Consider crop removal:

Soil nutrient removal by corn and soybeans.
 

Less grain and stover removal means less nutrient removal.

Nutrients removed at various corn yields:

Nutrients removed at various corn yields.
 

Nutrients removed at various soybean yields:

Soil Sampling in a Very Dry Fall

Soil sampling
 
  • Concern: Clay minerals shrink - hold potassium (K) ions
  • Result: Inaccurately low K soil test results
  • Action: Wait for adequate soil moisture before sampling

Nitrogen (N) Remaining in Corn Fields

  • Poor plant uptake of N due to dry weather
  • Nitrogen in nitrate form in the soil
  • Lack of moisture has prevented leaching or denitrification
  • Environmental loss of N has been minimal

Trap Crops

  • Wheat and cereal rye are best crops to prevent nitrogen loss
  • Nitrogen will not be available to the subsequent crop due to immobilization of N in the residue
  • When growing wheat for harvest, fall N can be eliminated while spring N may be reduced
  • Using trap crops improves organic matter and soil tilth, while improving water quality

Conclusions

  • Applying maintenance rates or no fertilizer may be acceptable depending on yield and previous soil test results
  • Avoid soil sampling until moisture levels return to normal
  • Wheat may be a good crop to take advantage of leftover nitrogen. Watch for head scab when planting wheat after corn.

 

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