Abstract
Abstract Deep placement of K fertilizer may alleviate late‐season K deficiency of cotton ( Gossypium hirsutum L.) on soils adequate in surface soil K but low in subsoil K. This 2‐yr study in Alabama evaluated effects of deep tillage (in‐row subsoiling) and K fertilizer placement on yield, leaf K deficiency, soil water depletion, and stomatal conductance of cotton grown on a soil with a root‐restricting hardpan. The Norfolk sandy loam (fine‐loamy, siliceous, thermic Typic Kandiudults) soil tested medium for K in the top 15 cm and low at greater depths. Treatments were: (i) no K, no subsoiling; (ii) no K, subsoiled; (iii) surface application (84 kg K ha −1 ), no subsoiling; (iv) surface application, subsoiled; and (v) deep placement in the subsoiled channel. Surface application without subsoiling resulted in the greatest soil water content (0‐ to 80‐cm depth); deep placement, the lowest. Stomatal conductance was highest with no‐K, no subsoiling and lowest with K (surface or deep), subsoiled. There was no evidence of K or drought stress‐induced stomatal closure, and stomatal closure was not related to severity of leaf K deficiency. All three K treatments increased leaf K concentration at early bloom. Subsoiling without K fertilizer increased plant size and severity of leaf K deficiency; with surface K, subsoiling more than doubled total leaf area but did not affect leaf K deficiency. Within subsoiled treatments, leaf K deficiency was more severe with deep placement of K than with surface application. Subsoiling, especially with K fertilizer, maximized seed cotton yield in both years (avg. 3261 kg ha −1 ) but reduced stomatal conductance. Stomatal closure and premature leaf senescence are not the likely mechanism for late‐season leaf K‐deficiency in cotton. Although subsoiling was necessary to maximize cotton yields on this Coastal Plain soil with a root‐restricting hardpan, deep placement of K fertilizer was not superior to surface application.
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Claims 16
Claim · model-written summary
Surface K without subsoiling had greatest soil water content; deep K placement had lowest.
- Treatment
- Surface application without subsoilinge0
- Outcome
- soil water contente0
- Direction
- greateste0
- Comparator
- deep placemente0
Not reportedTaxon
Verbatim
e0“Surface application without subsoiling resulted in the greatest soil water content (0‐ to 80‐cm depth); deep placement, the lowest.”
Claim · model-written summary
Stomatal conductance was highest without K or subsoiling.
- Treatment
- no‐K, no subsoilinge0
- Outcome
- Stomatal conductancee0
- Direction
- higheste0
- Comparator
- K (surface or deep), subsoilede0
Not reportedTaxon
Verbatim
e0“Stomatal conductance was highest with no‐K, no subsoiling and lowest with K (surface or deep), subsoiled.”
Claim · model-written summary
Stomatal conductance was lowest with K and subsoiling.
- Treatment
- K (surface or deep), subsoilede0
- Outcome
- Stomatal conductancee0
- Direction
- loweste0
- Comparator
- no‐K, no subsoilinge0
Not reportedTaxon
Verbatim
e0“Stomatal conductance was highest with no‐K, no subsoiling and lowest with K (surface or deep), subsoiled.”
Claim · model-written summary
There was no evidence of potassium or drought induced stomatal closure.
Not reportedTaxon
Verbatim
e0“There was no evidence of K or drought stress‐induced stomatal closure”
Claim · model-written summary
Stomatal closure was unrelated to leaf K deficiency severity.
- Organ / stage
- leafe0
- Outcome
- stomatal closuree0
- Direction
- not relatede0
- Qualifier
- severity of leaf K deficiencye0
Not reportedTaxon
Verbatim
e0“stomatal closure was not related to severity of leaf K deficiency.”
Claim · model-written summary
All three potassium treatments increased leaf K at early bloom.
- Organ / stage
- early bloome0
- Treatment
- three K treatmentse0
- Outcome
- leaf K concentratione0
- Direction
- increasede0
Not reportedTaxonComparator
Verbatim
e0“All three K treatments increased leaf K concentration at early bloom.”
Claim · model-written summary
Subsoiling without K increased cotton plant size.
Not reportedTaxonComparator
Verbatim
e0“Subsoiling without K fertilizer increased plant size and severity of leaf K deficiency”
Claim · model-written summary
Subsoiling without K increased leaf K deficiency severity.
- Treatment
- Subsoiling without K fertilizere0
- Outcome
- severity of leaf K deficiencye0
- Direction
- increasede0
Not reportedTaxonComparator
Verbatim
e0“Subsoiling without K fertilizer increased plant size and severity of leaf K deficiency”
Claim · model-written summary
With surface K, subsoiling more than doubled total leaf area.
Not reportedTaxonComparator
Verbatim
e0“with surface K, subsoiling more than doubled total leaf area but did not affect leaf K deficiency.”
Claim · model-written summary
With surface K, subsoiling did not affect leaf K deficiency.
Not reportedTaxonComparator
Verbatim
e0“with surface K, subsoiling more than doubled total leaf area but did not affect leaf K deficiency.”
Claim · model-written summary
Among subsoiled treatments, deep K placement caused more severe leaf deficiency than surface K.
- Treatment
- deep placement of Ke0
- Outcome
- leaf K deficiencye0
- Direction
- more severee0
- Comparator
- surface applicatione0
Not reportedTaxon
Verbatim
e0“Within subsoiled treatments, leaf K deficiency was more severe with deep placement of K than with surface application.”
Claim · model-written summary
Subsoiling, especially with K, maximized seed cotton yield in both years.
- Taxon
- cotton
Gossypium hirsutume0 - Treatment
- Subsoiling, especially with K fertilizere0
- Outcome
- seed cotton yielde0
- Direction
- maximizede0
- Value
- 3261 kg ha −1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Subsoiling, especially with K fertilizer, maximized seed cotton yield in both years (avg. 3261 kg ha −1 )”
Claim · model-written summary
Subsoiling with K reduced stomatal conductance.
Not reportedTaxonTreatmentComparator
Verbatim
e0“but reduced stomatal conductance.”
Claim · model-written summary
The authors reject stomatal closure and premature senescence as likely mechanisms of late-season K deficiency.
- Taxon
- cottonGossypium hirsutume0
- Outcome
- late‐season leaf K‐deficiencye0
- Qualifier
- Stomatal closure and premature leaf senescencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal closure and premature leaf senescence are not the likely mechanism for late‐season leaf K‐deficiency in cotton.”
Claim · model-written summary
Subsoiling was necessary for maximum cotton yield on this hardpan soil.
- Taxon
- cottonGossypium hirsutume0
- Outcome
- subsoiling was necessary to maximize cotton yieldse0
- Setting
- Coastal Plain soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“subsoiling was necessary to maximize cotton yields on this Coastal Plain soil with a root‐restricting hardpan”
Claim · model-written summary
Deep K placement was not superior to surface K application.
- Treatment
- deep placement of K fertilizere0
- Outcome
- not superiore0
- Direction
- not superiore0
- Comparator
- surface applicatione0
Not reportedTaxon
Verbatim
e0“deep placement of K fertilizer was not superior to surface application.”
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