Improvement of the N fertilizer efficiency with dicyandiamide (dcd) in citrus trees
1995
Serna, M.D. | Legaz, F. | Primo-Millo, E.
Nitrification inhibitors such a dicyandiamide (DCD) help to 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). Under field conditions, fertilization of adult trees with ASN (600 g N tree-1) either with or without DCD (2% DCD-N) was compared (ASN+DCD and ASN, respectively). The NH4(+)-N concentrations in plots fertilized with ASN+DCD were significantly higher than ASN plot in the 0-15 cm layer during 5-105 day period. Nitrification started immediately after N application in both treatments (ASN and ASN+DCD). In all three soil layers analyzed, NO(-3)-N concentrations were higher in the ASN plots than in the ASN+DCD during the first 20 days. This indicates that nitrification of NH+4 from ASN was more rapid in the absence of DCD. On the other hand, fertilization with ASN+DCD kept higher levels of NO(-3)-N in soils than ASN during the rest of experience period (40-160 days). Addition of DCD to ASN showed a higher N concentration in the spring-flush leaves with respect to the trees fertilized with ASN, during the growth cycle. These results suggest that the use of a nitrification inhibitor permitted a more efficient utilization of fertilizer N by citrus trees. The plants treated with DCD added to ASN showed a higher yield in number of units per tree and a better fruit colour index than those treated with ASN alone.
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