Abstract
Abstract The inefficiency of N use in soils has been studied widely, producing varied suggestions for increased effectiveness. The object of this research was to examine the use of Ca 2+ as a means to increase NH + 4 absorption, using onion ( Allium cepa L.) as a test crop. Ammonium absorption in the presence of variable Ca 2+ concentrations was measured in short‐term greenhouse studies as well as longterm greenhouse studies and field‐production trials. The greenhouse 15 NH + 4 absorption study was conducted in 4‐L pots containing 3.5 kg of calcareous Gila sandy loam (coarse‐loamy, mixed, calcareous, thermic Typic Torrifluvents). The long‐term growth study was conducted in calcareous quartz sand. Irrigation solutions consisted of half‐strength nutrient solutions (5 mol m −3 in NH + 4 ) with Ca 2+ :NH + 4 molar proportions of 0, 0.25, 0.50, 1.00, and 2.00. The 15 NH + 4 absorption study was conducted during a 30‐h period on 60‐d onion. The long‐term growth experiment received the same nutrient solutions until mature onion bulbs were produced (about 5 cm in diameter). A 2‐yr field production trial used single rows on 1‐m wide beds. The soil was a calcareous Saneli silty clay loam [clayey over sandy or sandy‐skeletal, montmorillonitic (calcareous), thermic Vertic Torrifluvent]. In 15 NH + 4 studies, NH + 4 absorption increased with added Ca by as much as 189% in onion bulbs and by 67% in onion tops relative to absorption with no Ca added. These maximum increases were in association with solution Ca 2+ :NH + 4 molar proportions (MP) of 0.5 in onion bulbs and 1.0 in onion tops. Total plant dry weights with Ca added increased as much as 100% in bulbs and 25% in tops in 30‐h 15 NH + 4 absorption tests over the 0 Ca 2+ controls. In greenhouse growth tests, vegetative matter increased as much as 40% with increasing Ca 2+ concentrations at constant NH + 4 levels compared to the 0 Ca 2+ control. This translated to increased total N absorption. In 2 yr of field testing with a MP of 0.25, mature bulbs from both years increased 64% over yields with urea alone. Thus the addition of Ca 2+ with urea produced significantly improved plant N‐use efficiencies (greater plant yield at the same level of N application). These results were suggested from both the short‐term greenhouse 15 NH + 4 absorption experiment and from the long‐term greenhouse growth trial.
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Claims 10
Claim · model-written summary
Added calcium increased onion-bulb ammonium absorption by up to 189% versus no calcium.
- Taxon
- onion
Allium cepae0 - Organ / stage
- bulbse0
- Treatment
- added Cae0
- Outcome
- NH + 4 absorptione0
- Direction
- increasede0
- Value
- 189%e0
- Comparator
- no Ca addede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NH + 4 absorption increased with added Ca by as much as 189% in onion bulbs”
e1“relative to absorption with no Ca added”
Claim · model-written summary
Added calcium increased onion-top ammonium absorption by 67% versus no calcium.
- Taxon
- onionAllium cepae0
- Organ / stage
- topse0
- Treatment
- added Cae1
- Outcome
- NH + 4 absorptione1
- Direction
- increasede1
- Value
- 67%e0
- Comparator
- no Ca addede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“by 67% in onion tops relative to absorption with no Ca added”
e1“NH + 4 absorption increased with added Ca”
Claim · model-written summary
Maximum bulb ammonium absorption occurred at calcium-to-ammonium molar proportion 0.5.
- Taxon
- onionAllium cepae0
- Organ / stage
- bulbse0
- Outcome
- maximum increasese0
- Value
- 0.5e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These maximum increases were in association with solution Ca 2+ :NH + 4 molar proportions (MP) of 0.5 in onion bulbs”
Claim · model-written summary
Maximum top ammonium absorption occurred at calcium-to-ammonium molar proportion 1.0.
- Taxon
- onionAllium cepae0
- Organ / stage
- topse0
- Outcome
- maximum increasese1
- Value
- 1.0e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“1.0 in onion tops”
e1“These maximum increases were in association with solution Ca 2+ :NH + 4 molar proportions (MP)”
Claim · model-written summary
Calcium raised bulb dry weight up to 100% over zero-calcium controls.
- Organ / stage
- bulbse0
- Treatment
- Ca addede0
- Outcome
- Total plant dry weightse0
- Direction
- increasede0
- Value
- 100%e0
- Comparator
- 0 Ca 2+ controlse0
Not reportedTaxon
Verbatim
e0“Total plant dry weights with Ca added increased as much as 100% in bulbs and 25% in tops in 30‐h 15 NH + 4 absorption tests over the 0 Ca 2+ controls.”
Claim · model-written summary
Calcium raised top dry weight up to 25% over zero-calcium controls.
- Taxon
- onionAllium cepae1
- Organ / stage
- topse0
- Treatment
- Ca addede0
- Outcome
- Total plant dry weightse0
- Direction
- increasede0
- Value
- 25%e0
- Comparator
- 0 Ca 2+ controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total plant dry weights with Ca added increased as much as 100% in bulbs and 25% in tops in 30‐h 15 NH + 4 absorption tests over the 0 Ca 2+ controls.”
e1“using onion ( Allium cepa L.) as a test crop”
Claim · model-written summary
With constant ammonium, increasing calcium raised vegetative matter up to 40% in greenhouse tests.
- Taxon
- onionAllium cepae1
- Treatment
- increasing Ca 2+ concentrationse0
- Outcome
- vegetative mattere0
- Direction
- increasede0
- Value
- 40%e0
- Comparator
- 0 Ca 2+ controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“vegetative matter increased as much as 40% with increasing Ca 2+ concentrations at constant NH + 4 levels compared to the 0 Ca 2+ control”
e1“using onion ( Allium cepa L.) as a test crop”
Claim · model-written summary
Increased vegetative matter translated into increased total nitrogen absorption.
- Taxon
- onionAllium cepae1
- Outcome
- total N absorptione0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This translated to increased total N absorption.”
e1“using onion ( Allium cepa L.) as a test crop”
Claim · model-written summary
Field addition of calcium with urea raised mature bulb yield 64% over urea alone in both years.
- Taxon
- onionAllium cepae2
- Organ / stage
- mature bulbse0
- Treatment
- addition of Ca 2+ with ureae1
- Outcome
- yieldse0
- Direction
- increasede0
- Value
- 64%e0
- Comparator
- urea alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mature bulbs from both years increased 64% over yields with urea alone”
e1“Thus the addition of Ca 2+ with urea”
e2“using onion ( Allium cepa L.) as a test crop”
Claim · model-written summary
Calcium with urea significantly improved plant nitrogen-use efficiency.
- Taxon
- onionAllium cepae1
- Treatment
- addition of Ca 2+ with ureae0
- Outcome
- plant N‐use efficienciese0
- Direction
- improvede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the addition of Ca 2+ with urea produced significantly improved plant N‐use efficiencies”
e1“using onion ( Allium cepa L.) as a test crop”
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See all 9 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.