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Crop News and Updates

Contributed by: Christy Hicks, Regional Extension Agent

Upcoming Events
June 6th – Autauga County Crop Scouting School
July 27th – Central AL Crops Tour

 

Cotton Re-plant Decisions (info from Univ. FL and Texas A&M)

Rainfall in our area from Saturday range from 3”-8” with more on the way.  Some fields may need to be accessed for replant decisions.  Here are some things to consider.

Cotton has a tremendous capacity to recover from adversities.  For cotton, there is little difference between 20,000-70,000 plants per acre when the stand is uniform.  That translates into 1.5-4.0 plants per foot.  Acceptable yields can be obtained from stands as low as 1-2 plants per row foot if the plants are uniformly spaced.  Later maturing varieties grown in our area are better able to compensate for low plant density than early maturing varieties grown in the Texas High Plains for example.  6’ skips with plants on either side have resulted in 13% yield losses.  Skips of 3’ with 3’ skips in adjacent rows result in more loss than longer skips with good stands on either side.  It is best to delay the final stand evaluation until after the cotton is exposed to 2-3 days of good growing conditions.  If the decision to replant is difficult, there are probably enough plants to keep the stand.

Thrips in Central AL corn this year.

Corn and N Loss by Denitrification and Leaching.

Every inch of rain can move nitrate 6-8” deeper in the soil profile in lighter textured soils.  Denitrification losses take place much slower than nitrate leaching.  Average N loss is usually around 2% of the nitrate per day of saturation.  The longer the soil remains saturated and the higher the temperature the more N is lost via dentrification.   The table below is based on Nitrogen loss mechanisms and experience from researchers at Purdue University.

Estimated Nitrogen Applications to Replace Lost Nitrogen in Corn (info from Purdue University)

Field Scenario Fields where urea or UAN applied more than 2 weeks prior to excessive rain if:
Silt loam or poorly drained field saturated long enough to kill the crop.
Sandy fields received more than 8” rain
Fields where urea or UAN applied 1-2 weeks prior to rain if:
Silt loam fields or poorly drained areas were saturated more than 3 days and crop survived.
Sandy fields received 4”-8” rain
Fields where N applied 2-7 days before an excessive rain if:
Silt loam or poorly drained field saturated less than 3 days.
Sandy fields received less than 4” rain
Should I apply N Likely additional N required Additional N may be required Not likely required
What Rate of N should I apply? 60-120 lbs N/ac. 30-60 lbs N/ac. none

Source: Camberato, J., Joern, B., and Nielsen, R.L. 2008. Nitrogen loss in wet and wetter fields. Purdue University. http://www.agry.purdue.edu.

Christy Hicks
Regional Extension Agent
Agronomic Crops
EV Smith Research Center
334-704-3370