Abstract
Nutrient management legislation has prompted an evaluation of alternative nitrogen (N) management techniques. SPAD (Soil Plant Analysis Development) chlorophyll and Cardy nitrate (NO 3 - ) meters were evaluated for their potential as tissue nitrogen tests in cabbage ( Brassica oleracea var. capitata ), onions ( Allium cepa ), and carrots ( Daucus carota subsp. sativus ). Cabbage, carrots, and onions were grown on both organic and mineral soils in Ontario, Canada in 2000 and 2001. Nitrogen was applied at five rates to cabbage and carrots and three rates to onions ranging from 0 to 200% of current provincial recommended N rates. In an additional treatment, 50% of the recommended rate was applied preplant and sidedress N applications of 40 kg·ha -1 (35.7 lb/acre) were applied when SPAD chlorophyll meter readings fell below 95 (2000) and 97% (2001) of the highest N rate treatment. Yields were generally unaffected by N rate, except in cabbage in 2000, suggesting adequate N was present in most treatments. SPAD chlorophyll meter readings were highly variable among soil types, cultivars, and years. Chlorophyll readings reached a plateau in adequately fertilized crops in many instances. Cardy readings were less variable among soil types, cultivars, and years. The relationship between N rate and sap NO 3 -N concentration was generally linear. The results suggest that the use of a well-fertilized reference plot is most appropriate for the SPAD meter on these vegetable crops, while the use of region-specific critical NO 3 -N concentrations was most appropriate for the Cardy NO 3 -meter. Both meters would be cost advantageous when over 500 samples are tested. The meters were generally easy to use, except for the SPAD meter on carrots. The meters have potential for N management of vegetable crops under Ontario growing conditions.
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Claims 10
Claim · model-written summary
Yields of cabbage, carrots and onions were generally unaffected by N rate, except in cabbage in 2000.
- Taxon
- Cabbage, carrots, and onions
Brassica oleracea var. capitata
Daucus carota
Allium cepae0 - Treatment
- N ratee1
- Outcome
- Yieldse1
- Direction
- unaffectede1
- Setting
- Ontario, Canadae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cabbage, carrots, and onions were grown on both organic and mineral soils in Ontario, Canada in 2000 and 2001”
e1“Yields were generally unaffected by N rate, except in cabbage in 2000”
Claim · model-written summary
SPAD chlorophyll meter readings were highly variable among soil types, cultivars and years.
Verbatim
e0“these vegetable crops”
e1“SPAD chlorophyll meter readings were highly variable among soil types, cultivars, and years”
Claim · model-written summary
Chlorophyll readings reached a plateau in adequately fertilized crops in many instances.
Verbatim
e0“these vegetable crops”
e1“Chlorophyll readings reached a plateau in adequately fertilized crops in many instances”
Claim · model-written summary
Cardy nitrate meter readings were less variable among soil types, cultivars and years.
Verbatim
e0“these vegetable crops”
e1“Cardy readings were less variable among soil types, cultivars, and years”
Claim · model-written summary
The relationship between N rate and sap NO3-N concentration was generally linear.
Not reportedDirection
Verbatim
e0“these vegetable crops”
e1“The relationship between N rate and sap NO 3 -N concentration was generally linear”
Claim · model-written summary
A well-fertilized reference plot is the most appropriate approach for the SPAD meter on these vegetable crops.
Verbatim
e0“the use of a well-fertilized reference plot is most appropriate for the SPAD meter on these vegetable crops”
Claim · model-written summary
Region-specific critical NO3-N concentrations are the most appropriate approach for the Cardy nitrate meter.
Verbatim
e0“these vegetable crops”
e1“the use of region-specific critical NO 3 -N concentrations was most appropriate for the Cardy NO 3 -meter”
Claim · model-written summary
Both meters would be cost advantageous when over 500 samples are tested.
Verbatim
e0“Both meters would be cost advantageous when over 500 samples are tested”
Claim · model-written summary
The meters were generally easy to use, except for the SPAD meter on carrots.
- Taxon
- carrotsDaucus carotae0
- Outcome
- generally easy to usee0
- Qualifier
- except for the SPAD meter on carrotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The meters were generally easy to use, except for the SPAD meter on carrots”
Claim · model-written summary
The meters have potential for N management of vegetable crops under Ontario growing conditions.
Verbatim
e0“The meters have potential for N management of vegetable crops under Ontario growing conditions”
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See all 184 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.