Abstract
Abstract Nitrification inhibitors such as dicyandiamide (DCD) help reduce leaching losses by retaining applied N in the ammoniacal form. Research objectives were to evaluate dicyandiamide added to ammonium sulphate nitrate (ASN) as a nitrification inhibitor in cultivated soils (Xeropsamments) and its effect on N uptake by citrus ( Citrus sinensis (L.) Osbeck). In a greenhouse experiment, 10 g N as ASN either with or without 2% of DCD‐N were applied to plants grown in 50‐L pots filled with peat and sand (2:1). Addition of DCD to ASN resulted in significantly higher levels of NH + 4 ‐N in the substrate than the ASN treatment, for at least 100 d. Drainage water from the ASN‐DCD treated pots was lower in NO − 3 ‐N concentration during the first 60 d. Inclusion of DCD with ASN resulted in greater uptake of the fertilizer N by citrus plants. Under field conditions, fertilization of adult trees with ASN (600 g N tree −1 ) either with or without DCD (2% DCD‐N) was compared. In the ASN‐amended soil, nitrification was much more rapid than when DCD was added to the ASN. Fertilization with ASN + DCD maintained relatively high levels of NO − 3 ‐N in soil longer than ASN alone. In another experiment, 60 g N as ASN either with or without DCD (2% DCD‐N) were applied to 3‐yr‐old citrus plants grown individually outdoors in containers and the distribution of NH + 4 ‐N and NO − 3 ‐N in the soil profile after consecutive flood irrigations was monitored. After the third irrigation, 68% of applied N was leached below 0.45 m in ASN amended soils, whereas only a very small amount of the applied N was retained above this depth. When DCD was added, only 20% of the applied N was lost by leaching at this time. The DCD nitrification inhibitor improved the N fertilizer efficiency and decreased NO − 3 losses so as to minimize the economic and environmental risks that are inherent in irrigated production of citrus.
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Claims 9
Claim · model-written summary
Adding DCD to ASN significantly increased substrate ammonium nitrogen for at least 100 days.
- Treatment
- DCD to ASNe0
- Outcome
- NH + 4 ‐N in the substratee0
- Direction
- highere0
- Qualifier
- for at least 100 de0
- Comparator
- ASN treatmente0
CitrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Addition of DCD to ASN resulted in significantly higher levels of NH + 4 ‐N in the substrate than the ASN treatment, for at least 100 d.”
t0“Citrus Production”
Claim · model-written summary
Drainage nitrate nitrogen was lower in DCD-treated pots during the first 60 days.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Drainage water from the ASN‐DCD treated pots was lower in NO − 3 ‐N concentration during the first 60 d.”
t0“Citrus Production”
Claim · model-written summary
Citrus plants took up more fertilizer nitrogen when DCD was included with ASN.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inclusion of DCD with ASN resulted in greater uptake of the fertilizer N by citrus plants.”
Claim · model-written summary
Soil nitrification was more rapid with ASN alone than when DCD was added.
- Treatment
- DCD was added to the ASNe0
- Outcome
- nitrificatione0
- Direction
- more rapide0
- Comparator
- ASN‐amended soile0
- Setting
- soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the ASN‐amended soil, nitrification was much more rapid than when DCD was added to the ASN.”
t0“Citrus Production”
Claim · model-written summary
ASN plus DCD maintained high soil nitrate nitrogen longer than ASN alone.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilization with ASN + DCD maintained relatively high levels of NO − 3 ‐N in soil longer than ASN alone.”
t0“Citrus Production”
Claim · model-written summary
After three irrigations, 68% of applied nitrogen leached below 0.45 m in ASN-amended soils.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After the third irrigation, 68% of applied N was leached below 0.45 m in ASN amended soils”
t0“Citrus Production”
Claim · model-written summary
With DCD, only 20% of applied nitrogen was lost by leaching after the third irrigation.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When DCD was added, only 20% of the applied N was lost by leaching at this time.”
t0“Citrus Production”
Claim · model-written summary
The authors concluded that DCD improved nitrogen fertilizer efficiency in citrus production.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The DCD nitrification inhibitor improved the N fertilizer efficiency”
t0“Citrus Production”
Claim · model-written summary
The authors concluded that DCD decreased nitrate losses in citrus production.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased NO − 3 losses so as to minimize the economic and environmental risks that are inherent in irrigated production of citrus.”
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