The Impact of Drought on Crop Nutrition

fallow brown agricultural field at great drought, crops

Many farmers across Western Canada experienced devastating drought conditions this year.  Besides causing crop moisture stress, dry soil limits root and soil biological activity, reducing soil nutrient availability and decreasing uptake. In this episode of Inputs by Top Crop Manager, Nutrien Senior Agronomist, Dr. Alan Blaylock, shared tips and advice on adjusting fertilizer-management strategies following drought. Listen to the recording or read through some of the highlights below.

 

  • Drought affects plant nutrition. Dry soil limits root activity and nutrient uptake, especially in roots close to the surface. Plant moisture stress can be compounded by nutrient stress. Soil organisms typically release nutrients for the plant to utilize, but during droughts they become less active, reducing nutrient availability for crops.
  • In circumstances where crops that were going to be used for grain must be harvested for livestock forage, harvesting the whole plant, not just seeds, increases nutrient removal. Most plant potassium occurs in leaves and stems. Removing the whole plant decreases the return of potassium (and other nutrients) to the soil in crop residues and can decrease potassium available to subsequent crops.
  • When yields are low and nutrient removal is unexpectedly low, unused nutrients can remain in the soil potentially reducing the fertilizer needs for the following season.
  • Residual nitrate-nitrogen in soil can contribute to the next seasons ‘nitrogen budget’ to potentially reduce fertilizers and costs. Identifying residual nitrate by soil testing is useful in Western Canada where winter nitrate-loss potential is minimal. In the higher rainfall of Eastern Canada over-winter nitrate loss is more likely and soil-nitrate tests have limited utility.
  • Following drought conditions, it is advisable to follow a planned program for your land and make small adjustments to nutrient needs based on soil testing, crop removal, yield potential, and other diagnostic tools.

How does drought affect ESN?

  • Moisture and temperature (not necessarily water) are the essential factors for the ESN release process. Moisture doesn’t become limiting to ESN release until soil water approaches the permanent wilting point.  Until that point there should be enough moisture for ESN to release.
  • ESN can help control early season nitrogen levels and vegetative growth thereby using less water during vegetative growth and conserving more for the reproductive period. Control of vegetative growth can result in yield increases despite dry conditions as has been observed in several studies in Canada and the U.S.
  • Those who experienced drought but are interested in fall application need to determine if the soil is suitable for fall application. If soil is excessively dry, nitrogen and ammonia applications could result in losses, and it may be best to wait until spring. However, one should balance that factor against potentially very wet conditions in the spring that can also result in losses. Determine what makes the most sense for your location and look at area history to see if you will be able to manage a good fall application.

To discuss how ESN works or if a fall application is right for your geography, get in touch with your local retailer or Nutrien representative.

 

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