Abstract
Abstract Hydroponic and greenhouse studies have shown that grain yields of wheat ( Triticum aestivum L.) are maximized when the N supply contains a mixture of NH 4 and NO 3 . Tillers per plant is the yield component most commonly increased by mixed N nutrition in greenhouse studies. The objective of this study was to evaluate, under field conditions, the response of ‘Butte 86’ spring wheat to N sources differing greatly in nitrification rate. Nitrogen was applied at 0 or 112 kg N ha ‐1 ; the N sources were calcium nitrate (CN), urea, ureadicyandiamide (DCD), 0.1‐g urea granules, and 0.1‐g urea–DCD granules. Six field trials were performed. Topsoil (0–15 cm) analysis of fertilized plots during tillering indicated a wide range of mineral N contents (19–101 mg N kg ‐1 ) and of NH 4 :NO 3 mole ratios (0.04–2.06). Correlation analyses suggested that tillering was sensitive to the total mineral N supply, but quite insensitive to the NH 4 :NO 3 ratio in the topsoil. Vegetative growth and N uptake were generally lower for CN than for the other N sources. At some locations, more heads per square meter at harvest were observed with the slower‐nitrifying N sources. Grain yields were increased by N fertilization, but significant differences between N sources were not generally observed. For both years of the study, the 0.1‐g urea‐DCD granules gave the highest N uptake efficiency. However, the dramatic responses in growth, tillering, or grain yield routinely observed with mixed N nutrition in hydroponic or greenhouse studies could not be duplicated in the field.
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Claims 9
Claim · model-written summary
Tillering was sensitive to total mineral N supply.
- Taxon
- wheat
Triticum aestivume1 - Treatment
- total mineral N supplye0
- Outcome
- tilleringe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tillering was sensitive to the total mineral N supply”
e1“wheat ( Triticum aestivum L.)”
Claim · model-written summary
Tillering was relatively insensitive to the topsoil NH 4 :NO 3 ratio.
- Taxon
- wheatTriticum aestivume2
- Compound
- NH 4 :NO 3e0
- Outcome
- tilleringe1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“quite insensitive to the NH 4 :NO 3 ratio in the topsoil”
e1“tillering was sensitive to the total mineral N supply”
e2“wheat ( Triticum aestivum L.)”
Claim · model-written summary
Vegetative growth was generally lower with CN than other N sources.
- Taxon
- wheatTriticum aestivume1
- Treatment
- CNe0
- Outcome
- Vegetative growthe0
- Direction
- lowere0
- Comparator
- the other N sourcese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Vegetative growth and N uptake were generally lower for CN than for the other N sources.”
e1“wheat ( Triticum aestivum L.)”
Claim · model-written summary
N uptake was generally lower with CN than other N sources.
- Taxon
- wheatTriticum aestivume1
- Treatment
- CNe0
- Outcome
- N uptakee0
- Direction
- lowere0
- Comparator
- the other N sourcese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Vegetative growth and N uptake were generally lower for CN than for the other N sources.”
e1“wheat ( Triticum aestivum L.)”
Claim · model-written summary
Slower nitrifying sources gave more heads per square meter at some locations.
- Taxon
- wheatTriticum aestivume1
- Treatment
- slower‐nitrifying N sourcese0
- Outcome
- heads per square meter at harveste0
- Direction
- moree0
- Qualifier
- At some locationse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At some locations, more heads per square meter at harvest were observed with the slower‐nitrifying N sources.”
e1“wheat ( Triticum aestivum L.)”
Claim · model-written summary
Nitrogen fertilization increased grain yield.
- Taxon
- wheatTriticum aestivume1
- Treatment
- N fertilizatione0
- Outcome
- Grain yieldse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yields were increased by N fertilization”
e1“wheat ( Triticum aestivum L.)”
Claim · model-written summary
Grain yields generally did not differ significantly among N sources.
- Taxon
- wheatTriticum aestivume2
- Treatment
- N sourcese0
- Outcome
- Grain yieldse1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant differences between N sources were not generally observed”
e1“Grain yields were increased by N fertilization”
e2“wheat ( Triticum aestivum L.)”
Claim · model-written summary
The 0.1‐g urea‐DCD granules gave the highest N uptake efficiency in both years.
- Taxon
- wheatTriticum aestivume1
- Treatment
- 0.1‐g urea‐DCD granulese0
- Outcome
- N uptake efficiencye0
- Direction
- higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For both years of the study, the 0.1‐g urea‐DCD granules gave the highest N uptake efficiency.”
e1“wheat ( Triticum aestivum L.)”
Claim · model-written summary
Large mixed-N responses seen in controlled studies were not duplicated in the field.
- Taxon
- wheatTriticum aestivume1
- Outcome
- growth, tillering, or grain yielde0
- Direction
- could not be duplicatede0
- Setting
- the fielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dramatic responses in growth, tillering, or grain yield routinely observed with mixed N nutrition in hydroponic or greenhouse studies could not be duplicated in the field.”
e1“wheat ( Triticum aestivum L.)”
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See all 3,438 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.