Abstract
In 2-years field experiments near Nienstädt (60 km west of Hannover, northern Germany), the effects of rate and timing of nitrogen (N) application on leaf N-concentration, leaf greenness (SPAD chlorophyll meter readings), canopy greenness (canopy light reflectance), leaf area development, photosynthetic activity of leaves, and yield and quality of sugar beet were studied. In 1999 (pre-planting soil mineral N: 15 kg ha—1), N fertilizer was applied at rates of 0, 105, 125, 145, 165 and 205 kg N ha—1. In 2000 (pre-planting soil mineral N: 60 kg ha—1), an N rate of 100 kg ha—1 was applied at planting (100/0/0/0) or split applied at planting and 8 (60/40/0/0), 12 (60/0/40/0), and 16 (60/0/0/40) weeks after planting (WAP), respectively. In both years, canopy greenness as indicated by ”︁sensor values” (a combination of the reflectance of visible and near infrared light) changed with crop age. However, at each time of measurement, sensor values precisely reflected the different N application treatments and were significantly correlated with leaf N-concentrations and SPAD chlorophyll meter readings. Beet yield and processed white sugar yield increased up to an N supply (fertilizer N + pre-planting soil mineral N) of 160 kg ha—1. Split N application slightly retarded leaf growth but had no effect on photosynthetic activity per unit leaf area. Beet yield and beet quality were not systematically affected by the timing of N application. Certain application schemes tended to favor either beet yield or beet quality, resulting in similar processed white sugar yields. Our data suggest that moderate N topdressing can be integrated in site-specific N management systems in sugar beet production. Canopy light reflectance might serve as a useful diagnostic tool to assess the N status and sidedress N demand of sugar beets. However, due to changing sensor values over time, on-site calibration (using established standard methods or reference plots receiving extra N at planting) will be necessary. The applicability of this approach has to be tested in further field studies.<?show $6#> <?show $38#Bo;>Die Pflanze als Indikator für den Stickstoff-Kopfdüngungsbedarf im Zuckerrübenanbau — Grenzen und Perspektiven In 2-jährigen Feldversuchen bei Nienstädt (60 km westlich von Hannover), wurde der Einfluss von Höhe und Zeitpunkt der Stickstoff (N)-Düngung auf den N-Ernährungsstatus der Pflanzen (Gesamt-N-Gehalte der Blätter, Chlorophyllmeterwerte der Blätter, Lichtreflexion des Bestandes), die Blattflächenentwicklung, die photosynthetische Aktivität der Blätter sowie Ertrag und Qualität von Zuckerrüben untersucht. Im Jahr 1999 (Nmin-Angebot des Bodens vor der Saat: 15 kg N ha—1) betrug die N-Düngung 0, 105, 125, 145, 165 und 205 kg ha—1. Im Jahr 2000 (Nmin-Angebot des Bodens vor der Saat: 60 kg N ha—1) wurde eine in der Höhe einheitliche N-Düngung (100 kg ha—1) ausschließlich zur Saat (100/0/0/0) oder in zwei Teilgaben zur Saat und 8 (60/40/0/0), 12 (60/0/40/0) bzw. 16 (60/0/0/40) Wochen nach der Saat (WAP) ausgebracht. Die mit Hilfe der berührungslosen Lichtreflexionsmessungen berechneten ”︁Sensorwerte” änderten sich mit dem Pflanzenalter. Sie spiegelten jedoch zu jedem Messzeitpunkt die unterschiedlichen N-Düngungsvarianten präzise wider und waren eng mit den gleichzeitig ermittelten Chlorophyllwerten bzw. N-Gehalten der Rübenblätter korreliert. Rüben- und Weißzuckerertrag stiegen bis zu einem N-Angebot von 160 kg ha—1 (Boden- + Dünger-N) an. Eine Zweiteilung der N-Düngung führte im Vergleich zu ausschließlicher Düngung zur Saat zu leicht verzögertem Blattwachstum, hatte aber keinen konsistenten Einfluss auf die photosynthetische Aktivität pro Einheit Blattfläche, den Rübenertrag und die Rübenqualität. Je nach Zeitpunkt der Kopfdüngung war entweder der Rübenertrag oder die Rübenqualität gefördert, was in ähnlichen bereinigten Zuckererträgen resultierte. Aus den Ergebnissen wird geschlossen, dass eine moderate N-Kopfdüngung als Element in ein standortspezifisches N-Management im Zuckerrübenanbau einbezogen werden kann. Berührungslose Lichtreflexionsmessungen könnten sich zur Ermittlung des N-Kopfdüngungsbedarfs von Zuckerrüben eignen, allerdings nur, wenn es gelingt diese mittels Standardmethoden oder erhöht gedüngter Referenzflächen zeit- bzw. standortspezifisch zu kalibrieren. Zur Etablierung entsprechender Düngungssysteme im Zuckerrübenanbau sind weitere Versuche erforderlich.
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Claims 11
Claim · model-written summary
Sensor values reflected the different N application treatments and were significantly correlated with leaf N-concentrations and SPAD chlorophyll meter readings
- Taxon
- sugar beet
Beta vulgaris subsp. vulgarist0 - Treatment
- N application treatmentse1
- Outcome
- sensor valuese1
- Qualifier
- leaf N-concentrations and SPAD chlorophyll meter readingse1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e1“sensor values precisely reflected the different N application treatments and were significantly correlated with leaf N-concentrations and SPAD chlorophyll meter readings”
Claim · model-written summary
Canopy greenness indicated by sensor values changed with crop age
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Outcome
- sensor valuese2
- Qualifier
- changed with crop agee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e2“changed with crop age. However, at each time of measurement, sensor values”
Claim · model-written summary
Beet yield and processed white sugar yield increased with N supply up to 160 kg ha—1 in sugar beet
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Treatment
- N supplye3
- Outcome
- Beet yield and processed white sugar yielde3
- Direction
- increasede3
- Value
- 160 kg ha—1e3
- Setting
- field experiments near Nienstädte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e0“In 2-years field experiments near Nienstädt”
e3“Beet yield and processed white sugar yield increased up to an N supply (fertilizer N + pre-planting soil mineral N) of 160 kg ha—1”
Claim · model-written summary
Split N application slightly retarded sugar beet leaf growth
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Treatment
- Split N applicatione4
- Outcome
- leaf growthe4
- Direction
- slightly retardede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e4“Split N application slightly retarded leaf growth but had no effect on photosynthetic activity per unit leaf area”
Claim · model-written summary
Split N application had no effect on photosynthetic activity per unit leaf area of sugar beet
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Treatment
- Split N applicatione4
- Outcome
- photosynthetic activity per unit leaf areae4
- Direction
- had no effecte4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e4“Split N application slightly retarded leaf growth but had no effect on photosynthetic activity per unit leaf area”
Claim · model-written summary
Beet yield and beet quality of sugar beet were not systematically affected by the timing of N application
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Treatment
- timing of N applicatione5
- Outcome
- Beet yield and beet qualitye5
- Direction
- not systematically affectede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e5“Beet yield and beet quality were not systematically affected by the timing of N application”
Claim · model-written summary
Certain N application schemes favored either beet yield or beet quality of sugar beet
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Treatment
- application schemese6
- Outcome
- beet yield or beet qualitye6
- Direction
- favore6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e6“Certain application schemes tended to favor either beet yield or beet quality, resulting in similar processed white sugar yields”
Claim · model-written summary
Processed white sugar yields of sugar beet were similar across the N application schemes
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Treatment
- application schemese6
- Outcome
- processed white sugar yieldse6
- Direction
- similare6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e6“Certain application schemes tended to favor either beet yield or beet quality, resulting in similar processed white sugar yields”
Claim · model-written summary
Moderate N topdressing can be integrated in site-specific N management systems in sugar beet production
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Outcome
- site-specific N management systemse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e7“moderate N topdressing can be integrated in site-specific N management systems in sugar beet production”
Claim · model-written summary
Canopy light reflectance might serve as a diagnostic tool to assess the N status and sidedress N demand of sugar beet
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Outcome
- diagnostic tool to assess the N status and sidedress N demande2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e2“Canopy light reflectance might serve as a useful diagnostic tool to assess the N status and sidedress N demand of sugar beets”
Claim · model-written summary
On-site calibration of sensor values is necessary for sugar beet N management
- Taxon
- sugar beetBeta vulgaris subsp. vulgarist0
- Outcome
- on-site calibratione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sugar beet production”
e2“on-site calibration (using established standard methods or reference plots receiving extra N at planting) will be necessary”
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See all 108 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.