Abstract
Abstract Alfalfa ( Medicago sativa L.) uses large amounts of soil K. The usual K source for fertilizing alfalfa is KCl. The purpose of the current study was to determine whether Cl and SO 4 ions can injure alfalfa when high rates of KCl and K 2 SO 4 are applied. A field stand of ‘Vernal’ alfalfa growing on low fertility Miami silt loam soil (Typic Hapludalf fine‐loamy mixed, mesic) was topdressed for 2 years with 0, 448, 896, 1,344, and 1,792 kg K/ha/year as either KCl or K 2 SO 4 . Four harvests were taken in 1972 and in 1973, and one in spring of 1974. Highest 2‐year total herbage yield occurred in KCl‐fertilized plots where 448 kg K/ha/year were applied; yields decreased significantly at rates higher than 896 kg K/ha/year. High yields were obtained at all rates of K 2 SO 4 . Highest K concentrations for both KCl and K 2 SO 4 ‐fertilized herbage occurred where 1,792 kg K/ha/year were applied in 1972 (3.70 and 3.77%, respectively) and in 1973 (3.04 and 3.41%, respectively). Chlorine concentrations in herbage fertilized with KCl ranged from 1.50 to 2.21% in 1972 and 0.82 to 1.15% in 1973. Chlorine concentrations in K 2 SO 4 ‐fertilized herbage were lower than in KCl‐fertilized herbage; less than 0.77% in 1972 and 0.42% in 1973. Sulfur concentrations in herbage fertilized with K 2 SO 4 ranged from 0.31 to 0.36% in 1972 and from 0.30 to 0.33% in 1973. Where KCl was applied, S concentrations were lower than the control (0.23% in 1972 and 0.26% in 1973). All applications of K lowered N concentrations below the control. It is evident that fertilizer rates higher than 896 kg K/ha/year as KCl can cause significant yield reductions. Therefore, when KCl fertilizer is topdressed at these rates, applications may have to be split among harvests or K 2 SO 4 may have to be substituted for KCl as all or part of the K fertilizer.
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Claims 15
Claim · model-written summary
Highest 2-year total herbage yield of alfalfa occurred in KCl-fertilized plots receiving 448 kg K/ha/year.
- Taxon
- Medicago sativa
Medicago sativae0 - Treatment
- 448 kg K/ha/yeare1
- Outcome
- total herbage yielde1
- Direction
- Higheste1
- Qualifier
- KCl‐fertilized plotse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Highest 2‐year total herbage yield occurred in KCl‐fertilized plots where 448 kg K/ha/year were applied”
Claim · model-written summary
In KCl-fertilized plots, alfalfa yields decreased significantly at rates higher than 896 kg K/ha/year.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- rates higher than 896 kg K/ha/yeare1
- Outcome
- yieldse1
- Direction
- decreasede1
- Qualifier
- KCl‐fertilized plotse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“KCl‐fertilized plots where 448 kg K/ha/year were applied; yields decreased significantly at rates higher than 896 kg K/ha/year”
Claim · model-written summary
High alfalfa yields were obtained at all rates of K2SO4.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- K 2 SO 4e1
- Outcome
- yieldse1
- Direction
- Highe1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“High yields were obtained at all rates of K 2 SO 4”
Claim · model-written summary
Highest herbage K concentration with KCl was 3.70% where 1,792 kg K/ha/year were applied in 1972.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- KCle1
- Outcome
- K concentrationse1
- Direction
- Higheste1
- Value
- 3.70e1
- Qualifier
- 1,792 kg K/ha/year were applied in 1972e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Highest K concentrations for both KCl and K 2 SO 4 ‐fertilized herbage occurred where 1,792 kg K/ha/year were applied in 1972 (3.70 and 3.77%, respectively) and in 1973 (3.04 and 3.41%, respectively)”
Claim · model-written summary
Highest herbage K concentration with K2SO4 was 3.77% where 1,792 kg K/ha/year were applied in 1972.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- K 2 SO 4e1
- Outcome
- K concentrationse1
- Direction
- Higheste1
- Value
- 3.77%e1
- Qualifier
- 1,792 kg K/ha/year were applied in 1972e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Highest K concentrations for both KCl and K 2 SO 4 ‐fertilized herbage occurred where 1,792 kg K/ha/year were applied in 1972 (3.70 and 3.77%, respectively) and in 1973 (3.04 and 3.41%, respectively)”
Claim · model-written summary
Chlorine concentrations in KCl-fertilized herbage ranged from 1.50 to 2.21% in 1972.
- Taxon
- Medicago sativaMedicago sativae0
- Outcome
- Chlorine concentrationse1
- Value
- 1.50 to 2.21%e1
- Qualifier
- KCle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Chlorine concentrations in herbage fertilized with KCl ranged from 1.50 to 2.21% in 1972 and 0.82 to 1.15% in 1973”
Claim · model-written summary
Chlorine concentrations in KCl-fertilized herbage ranged from 0.82 to 1.15% in 1973.
- Taxon
- Medicago sativaMedicago sativae0
- Outcome
- Chlorine concentrationse1
- Value
- 0.82 to 1.15%e1
- Qualifier
- KCle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Chlorine concentrations in herbage fertilized with KCl ranged from 1.50 to 2.21% in 1972 and 0.82 to 1.15% in 1973”
Claim · model-written summary
Chlorine concentrations in K2SO4-fertilized herbage were lower than in KCl-fertilized herbage, less than 0.77% in 1972.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- K 2 SO 4e1
- Outcome
- Chlorine concentrationse1
- Direction
- lowere1
- Value
- 0.77%e1
- Qualifier
- 1972e1
- Comparator
- KCl‐fertilized herbagee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Chlorine concentrations in K 2 SO 4 ‐fertilized herbage were lower than in KCl‐fertilized herbage; less than 0.77% in 1972 and 0.42% in 1973”
Claim · model-written summary
Chlorine concentrations in K2SO4-fertilized herbage were lower than in KCl-fertilized herbage, less than 0.42% in 1973.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- K 2 SO 4e1
- Outcome
- Chlorine concentrationse1
- Direction
- lowere1
- Value
- 0.42%e1
- Qualifier
- 1973e1
- Comparator
- KCl‐fertilized herbagee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Chlorine concentrations in K 2 SO 4 ‐fertilized herbage were lower than in KCl‐fertilized herbage; less than 0.77% in 1972 and 0.42% in 1973”
Claim · model-written summary
Sulfur concentrations in K2SO4-fertilized alfalfa herbage ranged from 0.31 to 0.36% in 1972.
- Taxon
- Medicago sativaMedicago sativae0
- Outcome
- Sulfur concentrationse1
- Value
- 0.31 to 0.36%e1
- Qualifier
- K 2 SO 4e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Sulfur concentrations in herbage fertilized with K 2 SO 4 ranged from 0.31 to 0.36% in 1972 and from 0.30 to 0.33% in 1973”
Claim · model-written summary
Sulfur concentrations in K2SO4-fertilized alfalfa herbage ranged from 0.30 to 0.33% in 1973.
- Taxon
- Medicago sativaMedicago sativae0
- Outcome
- Sulfur concentrationse1
- Value
- 0.30 to 0.33%e1
- Qualifier
- K 2 SO 4e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Sulfur concentrations in herbage fertilized with K 2 SO 4 ranged from 0.31 to 0.36% in 1972 and from 0.30 to 0.33% in 1973”
Claim · model-written summary
Where KCl was applied, S concentrations were lower than the control (0.23% in 1972).
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- KCle1
- Outcome
- S concentrationse1
- Direction
- lowere1
- Value
- 0.23%e1
- Qualifier
- 1972e1
- Comparator
- controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Where KCl was applied, S concentrations were lower than the control (0.23% in 1972 and 0.26% in 1973)”
Claim · model-written summary
Where KCl was applied, S concentrations were lower than the control (0.26% in 1973).
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- KCle1
- Outcome
- S concentrationse1
- Direction
- lowere1
- Value
- 0.26%e1
- Qualifier
- 1973e1
- Comparator
- controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“Where KCl was applied, S concentrations were lower than the control (0.23% in 1972 and 0.26% in 1973)”
Claim · model-written summary
All applications of K lowered N concentrations in alfalfa below the control.
- Taxon
- Medicago sativaMedicago sativae0
- Treatment
- applications of Ke1
- Outcome
- N concentrationse1
- Direction
- lowerede1
- Comparator
- controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“All applications of K lowered N concentrations below the control”
Claim · model-written summary
The authors recommend that, when KCl is topdressed at rates above 896 kg K/ha/year, applications may have to be split among harvests or K2SO4 substituted for KCl as all or part of the K fertilizer.
- Taxon
- Medicago sativaMedicago sativae0
- Outcome
- applications may have to be split among harvests or K 2 SO 4 may have to be substituted for KCle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicago sativa”
e1“applications may have to be split among harvests or K 2 SO 4 may have to be substituted for KCl as all or part of the K fertilizer”
The same questions in other papers
potassium sulfate · yield · Medicago sativa (alfalfa)Results agree
5 papers in the same direction as this paper
- positive
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See all 6 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.