Abstract
Research on relationships between K fertilization, crop yield, and tissue K concentration is needed for modern corn (Zea mays L.) hybrids and soybean (Glycine max L. Merr.) varieties. Twenty 2-yr trials with these crops in Iowa evaluated K effects on plant dry weight (DW), K concentration, and accumulation at the V5-V6 stage; leaf K concentration (R1 stage in corn and R2 in soybean); and grain yield, K concentration, and K removal. Five K rates (0–168 kg K ha-1) were broadcast the first year (10 sites for each crop). Potassium increased corn or soybean yield at 16 site-years, which had soil K ≤ 173 mg K kg-1 (15-cm depth, CH3COONH4 test). On average across first-year responsive crops, 91 and 103 kg K ha-1 maximized corn and soybean yield, respectively, and across second-year crops the response was linear. Potassium fertilization increased grain K concentration and K removal to a greater extent and more frequently in soybean than in corn (10 vs. 5 site-years, respectively, for concentration and 11 vs. 3 site-years, respectively, for removal). The magnitude and frequency of responses for both crops were greatest for vegetative tissue K concentration and smaller (in decreasing order) for grain yield and K removal, grain K concentration, and early DW. There was large luxury K accumulation in vegetative tissues. Critical tissue K concentration ranges defined by two models were 20.2 to 25.1, 10.2 to 11.0, and 17.6 to 20.0 g K kg-1 for corn plants, corn leaves, and soybean leaves, respectively, and could not be determined for soybean plants.
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Claims 14
Claim · model-written summary
Potassium fertilization increased corn or soybean yield at 16 site-years with soil K at or below 173 mg K kg-1.
- Taxon
- corn or soybean
Glycine max
Zea mays subsp. mayse1 - Treatment
- Potassiume1
- Outcome
- yielde1
- Direction
- increasede1
- Qualifier
- soil K ≤ 173 mg K kg-1e1
- Setting
- Iowae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Twenty 2-yr trials with these crops in Iowa”
e1“Potassium increased corn or soybean yield at 16 site-years, which had soil K ≤ 173 mg K kg-1”
Claim · model-written summary
On average across first-year responsive crops, 91 kg K ha-1 maximized corn yield.
- Taxon
- cornZea mays subsp. mayse2
- Treatment
- kg K ha-1e2
- Outcome
- yielde2
- Direction
- maximizede2
- Value
- 91e2
- Qualifier
- first-year responsive cropse2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“On average across first-year responsive crops, 91 and 103 kg K ha-1 maximized corn and soybean yield, respectively, and across second-year crops the response was linear”
Claim · model-written summary
On average across first-year responsive crops, 103 kg K ha-1 maximized soybean yield.
- Taxon
- soybeanGlycine maxe2
- Treatment
- kg K ha-1e2
- Outcome
- yielde2
- Direction
- maximizede2
- Value
- 103e2
- Qualifier
- first-year responsive cropse2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“On average across first-year responsive crops, 91 and 103 kg K ha-1 maximized corn and soybean yield, respectively, and across second-year crops the response was linear”
Claim · model-written summary
Across second-year crops the response of corn and soybean to K was linear.
- Taxon
- Corn and SoybeanGlycine maxZea mays subsp. mayst0
- Treatment
- kg K ha-1e2
- Outcome
- responsee2
- Qualifier
- across second-year cropse2
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Corn and Soybean Tissue Potassium Content”
e2“On average across first-year responsive crops, 91 and 103 kg K ha-1 maximized corn and soybean yield, respectively, and across second-year crops the response was linear”
Claim · model-written summary
Potassium fertilization increased grain K concentration in soybean more than in corn, in 10 versus 5 site-years.
- Taxon
- soybeanGlycine maxe3
- Treatment
- Potassium fertilizatione3
- Outcome
- grain K concentratione3
- Direction
- increasede3
- Value
- 10 vs. 5 site-yearse3
- Qualifier
- to a greater extent and more frequentlye3
- Comparator
- corne3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Potassium fertilization increased grain K concentration and K removal to a greater extent and more frequently in soybean than in corn (10 vs. 5 site-years, respectively, for concentration and 11 vs. 3 site-years, respectively, for removal)”
Claim · model-written summary
Potassium fertilization increased K removal in soybean more than in corn, in 11 versus 3 site-years.
- Taxon
- soybeanGlycine maxe3
- Treatment
- Potassium fertilizatione3
- Outcome
- K removale3
- Direction
- increasede3
- Value
- 11 vs. 3 site-yearse3
- Qualifier
- to a greater extent and more frequentlye3
- Comparator
- corne3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Potassium fertilization increased grain K concentration and K removal to a greater extent and more frequently in soybean than in corn (10 vs. 5 site-years, respectively, for concentration and 11 vs. 3 site-years, respectively, for removal)”
Claim · model-written summary
Responses to K were greatest for vegetative tissue K concentration in both crops.
- Taxon
- Corn and SoybeanGlycine maxZea mays subsp. mayst0
- Organ / stage
- vegetative tissuee4
- Outcome
- magnitude and frequency of responsese4
- Direction
- greateste4
- Comparator
- vegetative tissue K concentratione4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Corn and Soybean Tissue Potassium Content”
e4“The magnitude and frequency of responses for both crops were greatest for vegetative tissue K concentration and smaller (in decreasing order) for grain yield and K removal, grain K concentration, and early DW”
Claim · model-written summary
Responses for grain yield and K removal were smaller than for vegetative tissue K concentration.
- Taxon
- Corn and SoybeanGlycine maxZea mays subsp. mayst0
- Outcome
- grain yield and K removale4
- Direction
- smallere4
- Comparator
- vegetative tissue K concentratione4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Corn and Soybean Tissue Potassium Content”
e4“The magnitude and frequency of responses for both crops were greatest for vegetative tissue K concentration and smaller (in decreasing order) for grain yield and K removal, grain K concentration, and early DW”
Claim · model-written summary
Responses for grain K concentration and early dry weight were smaller than for vegetative tissue K concentration.
- Taxon
- Corn and SoybeanGlycine maxZea mays subsp. mayst0
- Outcome
- grain K concentration, and early DWe4
- Direction
- smallere4
- Comparator
- vegetative tissue K concentratione4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Corn and Soybean Tissue Potassium Content”
e4“The magnitude and frequency of responses for both crops were greatest for vegetative tissue K concentration and smaller (in decreasing order) for grain yield and K removal, grain K concentration, and early DW”
Claim · model-written summary
Large luxury K accumulation occurred in vegetative tissues.
- Taxon
- Corn and SoybeanGlycine maxZea mays subsp. mayst0
- Organ / stage
- vegetative tissuese5
- Outcome
- luxury K accumulatione5
- Qualifier
- largee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Corn and Soybean Tissue Potassium Content”
e5“There was large luxury K accumulation in vegetative tissues”
Claim · model-written summary
The critical tissue K concentration range for corn plants was 20.2 to 25.1 g K kg-1.
- Taxon
- cornZea mays subsp. mayse6
- Organ / stage
- corn plantse6
- Outcome
- Critical tissue K concentratione6
- Value
- 20.2 to 25.1e6
- Qualifier
- g K kg-1e6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Critical tissue K concentration ranges defined by two models were 20.2 to 25.1, 10.2 to 11.0, and 17.6 to 20.0 g K kg-1 for corn plants, corn leaves, and soybean leaves, respectively, and could not be determined for soybean plants”
Claim · model-written summary
The critical tissue K concentration range for corn leaves was 10.2 to 11.0 g K kg-1.
- Taxon
- cornZea mays subsp. mayse6
- Organ / stage
- corn leavese6
- Outcome
- Critical tissue K concentratione6
- Value
- 10.2 to 11.0e6
- Qualifier
- g K kg-1e6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Critical tissue K concentration ranges defined by two models were 20.2 to 25.1, 10.2 to 11.0, and 17.6 to 20.0 g K kg-1 for corn plants, corn leaves, and soybean leaves, respectively, and could not be determined for soybean plants”
Claim · model-written summary
The critical tissue K concentration range for soybean leaves was 17.6 to 20.0 g K kg-1.
- Taxon
- soybeanGlycine maxe6
- Organ / stage
- soybean leavese6
- Outcome
- Critical tissue K concentratione6
- Value
- 17.6 to 20.0e6
- Qualifier
- g K kg-1e6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Critical tissue K concentration ranges defined by two models were 20.2 to 25.1, 10.2 to 11.0, and 17.6 to 20.0 g K kg-1 for corn plants, corn leaves, and soybean leaves, respectively, and could not be determined for soybean plants”
Claim · model-written summary
A critical tissue K concentration range could not be determined for soybean plants.
- Taxon
- soybeanGlycine maxe6
- Organ / stage
- soybean plantse6
- Outcome
- Critical tissue K concentratione6
- Qualifier
- could not be determinede6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“Critical tissue K concentration ranges defined by two models were 20.2 to 25.1, 10.2 to 11.0, and 17.6 to 20.0 g K kg-1 for corn plants, corn leaves, and soybean leaves, respectively, and could not be determined for soybean plants”
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