Abstract
Abstract The purpose of this study was to determine the effect of fertilizer application on corn yields and the composition of certain leaves, and the relationships between leaf composition and yields. Three experiments differing in details were conducted under irrigation with hybrid Iowa 939 corn in central Washington. Leaves were selected at several growth stages, but the second leaf below the ear collected at silking was studied most intensively. Analyses were made for total N, P, Ca, Mg, K, and Mn and for P soluble in 2% acetic acid. Only N increased yields significantly; K and P applications did not. Calcium nitrate was least effective of the five N sources used. Total N content of leaves selected prior to silking gave lower correlations with yield than those selected at silking. Yields were highly positively correlated with both N and total P contents of leaves selected at silking, and total P and N contents of leaves were also highly correlated. Partial regression analysis showed that leaf N was probably the dominant determinant of yield, but that the leaf P content was sometimes important. For the three experiments the regression coefficients of yield on leaf N content were not significantly different, but the intercepts were markedly different. In one experiment, yields declined 15 bushels per acre for each leaf per plant showing N deficiency symptoms at silking. The minimum leaf N percentage associated with no evidence of the characteristic tip firing of N deficiency appears to be far below the reported critical N concentrations for maximum yield. Ammonium sulfate produced the highest leaf P and K contents and the lowest Ca and Mg contents in comparison with Ca(NO 3 ) 2 and NH 4 NO 3 as N sources. The sum of the determined cations Ca, Mg and K in leaves selected at silking tends to be a constant at about 100 m.c. per 100 gm. Phosphorus soluble in 2% acetic acid was a linear function of and equal to about two‐thirds of the total P over a wide range of total P in the leaves.
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Claims 18
Claim · model-written summary
Nitrogen alone significantly increased corn yield.
- Taxon
- Corn
Zea mays subsp. mayst0 - Treatment
- Ne0
- Outcome
- yieldse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only N increased yields significantly; K and P applications did not”
t0“Corn”
Claim · model-written summary
Potassium application did not significantly increase corn yield.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- Ke0
- Outcome
- yieldse0
- Direction
- did note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only N increased yields significantly; K and P applications did not”
t0“Corn”
Claim · model-written summary
Phosphorus application did not significantly increase corn yield.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- P applicationse0
- Outcome
- yieldse0
- Direction
- did note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only N increased yields significantly; K and P applications did not”
t0“Corn”
Claim · model-written summary
Calcium nitrate was the least effective of five nitrogen sources.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- Calcium nitratee0
- Outcome
- least effectivee0
- Direction
- least effectivee0
- Comparator
- five N sourcese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Calcium nitrate was least effective of the five N sources used”
t0“Corn”
Claim · model-written summary
Leaf nitrogen before silking had lower yield correlation than leaf nitrogen at silking.
- Taxon
- CornZea mays subsp. mayst0
- Organ / stage
- leaves selected prior to silkinge0
- Outcome
- correlations with yielde0
- Direction
- lowere0
- Comparator
- those selected at silkinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total N content of leaves selected prior to silking gave lower correlations with yield than those selected at silking”
t0“Corn”
Claim · model-written summary
Yield correlated strongly and positively with leaf nitrogen at silking.
- Taxon
- CornZea mays subsp. mayst0
- Organ / stage
- leaves selected at silkinge0
- Compound
- Ne0
- Outcome
- Yieldse0
- Direction
- highly positively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Yields were highly positively correlated with both N and total P contents of leaves selected at silking”
t0“Corn”
Claim · model-written summary
Yield correlated strongly and positively with total leaf phosphorus at silking.
- Taxon
- CornZea mays subsp. mayst0
- Organ / stage
- leaves selected at silkinge0
- Compound
- total Pe0
- Outcome
- Yieldse0
- Direction
- highly positively correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Yields were highly positively correlated with both N and total P contents of leaves selected at silking”
t0“Corn”
Claim · model-written summary
Leaf phosphorus and nitrogen contents were highly correlated.
- Taxon
- CornZea mays subsp. mayst0
- Compound
- Ne0
- Outcome
- total Pe0
- Direction
- highly correlatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total P and N contents of leaves were also highly correlated”
t0“Corn”
Claim · model-written summary
Leaf nitrogen was probably the dominant yield determinant in partial regression.
- Taxon
- CornZea mays subsp. mayst0
- Compound
- leaf Ne0
- Outcome
- yielde0
- Qualifier
- probablye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Partial regression analysis showed that leaf N was probably the dominant determinant of yield”
t0“Corn”
Claim · model-written summary
Leaf phosphorus was sometimes important for yield.
- Taxon
- CornZea mays subsp. mayst0
- Compound
- leaf Pe0
- Outcome
- yielde1
- Qualifier
- sometimese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“leaf P content was sometimes important”
e1“dominant determinant of yield”
t0“Corn”
Claim · model-written summary
The yield-on-leaf-nitrogen regression coefficients did not differ significantly across three experiments.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- regression coefficients of yield on leaf N contente0
- Direction
- not significantly differente0
- Setting
- three experimentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For the three experiments the regression coefficients of yield on leaf N content were not significantly different”
t0“Corn”
Claim · model-written summary
The yield-on-leaf-nitrogen regression intercepts differed markedly across experiments.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- interceptse0
- Direction
- markedly differente0
- Setting
- three experimentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but the intercepts were markedly different”
e1“For the three experiments the regression coefficients of yield on leaf N content were not significantly different”
t0“Corn”
Claim · model-written summary
Yield declined 15 bushels per acre for each leaf with nitrogen deficiency symptoms at silking.
- Taxon
- CornZea mays subsp. mayst0
- Organ / stage
- leafe0
- Outcome
- yieldse0
- Direction
- declinede0
- Value
- 15 bushels per acree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“yields declined 15 bushels per acre for each leaf per plant showing N deficiency symptoms at silking”
t0“Corn”
Claim · model-written summary
The minimum symptom-free leaf nitrogen percentage appeared far below the reported critical percentage for maximum yield.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- minimum leaf N percentagee0
- Direction
- far belowe0
- Comparator
- reported critical N concentrations for maximum yielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The minimum leaf N percentage associated with no evidence of the characteristic tip firing of N deficiency appears to be far below the reported critical N concentrations for maximum yield”
t0“Corn”
Claim · model-written summary
Ammonium sulfate produced the highest leaf phosphorus and potassium contents versus calcium nitrate and ammonium nitrate.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- Ammonium sulfatee0
- Outcome
- leaf P and K contentse0
- Direction
- higheste0
- Comparator
- Ca(NO 3 ) 2 and NH 4 NO 3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ammonium sulfate produced the highest leaf P and K contents and the lowest Ca and Mg contents in comparison with Ca(NO 3 ) 2 and NH 4 NO 3 as N sources”
t0“Corn”
Claim · model-written summary
Ammonium sulfate produced the lowest leaf calcium and magnesium contents versus calcium nitrate and ammonium nitrate.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- Ammonium sulfatee0
- Outcome
- Ca and Mg contentse0
- Direction
- loweste0
- Comparator
- Ca(NO 3 ) 2 and NH 4 NO 3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ammonium sulfate produced the highest leaf P and K contents and the lowest Ca and Mg contents in comparison with Ca(NO 3 ) 2 and NH 4 NO 3 as N sources”
t0“Corn”
Claim · model-written summary
The sum of three leaf cations at silking tended to stay near 100 m.c. per 100 gm.
- Taxon
- CornZea mays subsp. mayst0
- Organ / stage
- leaves selected at silkinge0
- Outcome
- sum of the determined cations Ca, Mg and Ke0
- Direction
- constante0
- Value
- about 100 m.c. per 100 gme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The sum of the determined cations Ca, Mg and K in leaves selected at silking tends to be a constant at about 100 m.c. per 100 gm”
t0“Corn”
Claim · model-written summary
Acetic-acid-soluble phosphorus was linear with and about two-thirds of total leaf phosphorus.
- Taxon
- CornZea mays subsp. mayst0
- Compound
- total Pe0
- Outcome
- Phosphorus soluble in 2% acetic acide0
- Direction
- lineare0
- Value
- about two‐thirdse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phosphorus soluble in 2% acetic acid was a linear function of and equal to about two‐thirds of the total P over a wide range of total P in the leaves”
t0“Corn”
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1,905 papers in the same direction as this paper · 234 in the opposite direction · 45 reporting no difference from an alternative
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See all 2,185 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.