Abstract
A field experiment was conducted during 1999-2002 in central Arizona to evaluate effects of N application rate and frequency on fruit yield, leaf N concentration, and residual soil N of 3 to 6-year-old 'Newhall' navel oranges (Citrus sinensis L. Osbeck) on Carrizo citrange (Porcirus trifoliate x C. sinensis) rootstock. Trees were grown in a calcareous fine sandy loam and were well-watered, producing a small positive leaching fraction. The experiment included nonfertilized control plots, and factorial combinations of three fertigation frequencies (27, 9, and 3 applications per year) and three N rates (68, 136, or 204 g/tree per year = 0.15, 0.30, 0.45 lb) from urea ammonium nitrate (32-0-0) applied through microsprinklers. Maximum yields occurred at interpolated N rates of 105 to 153 g/tree per year (= 0.23 to 0.34 lb) for the fourth to the sixth growing seasons. These rates were equivalent to only 17% to 34% of currently recommended N rates for flood-irrigated citrus grown in Arizona. Fruit size and juice quality were not affected by N rate or fertigation frequency. Leaf N concentrations were above 2.7% at yield-maximizing N rates. Highest concentrations of residual soil NO3 resulted from the highest N rate. Fertigation frequency did not significantly affect residual soil NO3. Optimum N rates for young microsprinkler-irrigated 'Newhall' navel orange trees in Arizona were much lower than the currently recommended N rates.
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Claims 7
Claim · model-written summary
Fruit yield was maximal at interpolated nitrogen rates of 105 to 153 g/tree per year in the fourth through sixth growing seasons.
- Taxon
- navel orange trees
Citrus sinensist0 - Treatment
- N rates of 105 to 153 g/tree per yeare0
- Outcome
- yieldse0
- Direction
- Maximume0
- Value
- 105 to 153 g/tree per yeare0
- Qualifier
- fourth to the sixth growing seasonse0
Not reportedMaterialComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“navel orange trees”
e0“Maximum yields occurred at interpolated N rates of 105 to 153 g/tree per year (= 0.23 to 0.34 lb) for the fourth to the sixth growing seasons.”
Claim · model-written summary
Yield-maximizing nitrogen rates were 17% to 34% of current recommendations for flood-irrigated Arizona citrus.
- Taxon
- navel orange treesCitrus sinensist0
- Outcome
- N ratese0
- Value
- 17% to 34%e0
- Comparator
- currently recommended N ratese0
- Setting
- Arizonae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“navel orange trees”
e0“These rates were equivalent to only 17% to 34% of currently recommended N rates for flood-irrigated citrus grown in Arizona.”
Claim · model-written summary
Nitrogen rate and fertigation frequency did not affect fruit size or juice quality.
- Taxon
- navel orange treesCitrus sinensist0
- Treatment
- N rate or fertigation frequencye0
- Outcome
- Fruit size and juice qualitye0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“navel orange trees”
e0“Fruit size and juice quality were not affected by N rate or fertigation frequency.”
Claim · model-written summary
Leaf nitrogen concentrations exceeded 2.7% at yield-maximizing nitrogen rates.
- Taxon
- navel orange treesCitrus sinensist0
- Organ / stage
- Leafe0
- Outcome
- Leaf N concentrationse0
- Direction
- abovee0
- Value
- 2.7%e0
- Qualifier
- yield-maximizing N ratese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“navel orange trees”
e0“Leaf N concentrations were above 2.7% at yield-maximizing N rates.”
Claim · model-written summary
The highest nitrogen rate produced the highest residual soil nitrate concentration.
- Taxon
- navel orange treesCitrus sinensist0
- Treatment
- highest N ratee0
- Outcome
- concentrations of residual soil NO3e0
- Direction
- Higheste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“navel orange trees”
e0“Highest concentrations of residual soil NO3 resulted from the highest N rate.”
Claim · model-written summary
Fertigation frequency did not significantly affect residual soil nitrate.
- Taxon
- navel orange treesCitrus sinensist0
- Treatment
- Fertigation frequencye0
- Outcome
- residual soil NO3e0
- Direction
- did not significantly affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“navel orange trees”
e0“Fertigation frequency did not significantly affect residual soil NO3.”
Claim · model-written summary
The authors conclude that optimal nitrogen rates for young microsprinkler-irrigated Newhall navel orange trees in Arizona are much lower than current recommendations.
- Taxon
- navel orange treesCitrus sinensist0
- Material
- Newhalle0
- Outcome
- Optimum N ratese0
- Direction
- much lowere0
- Comparator
- currently recommended N ratese0
- Setting
- Arizonae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“navel orange trees”
e0“Optimum N rates for young microsprinkler-irrigated 'Newhall' navel orange trees in Arizona were much lower than the currently recommended N rates.”
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See all 12 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.