Evaluation of fertilization with uncoated urea and 3,4-dimethylpyrazole phosphate (DMPP)-coated urea on nitrogen leaching and rose (Rosa spp.) yield

The negative impact of N over-fertilization has acquired importance in rose (Rosa spp.) growers in Colombia. The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) has been considered a valuable alternative to diminish the N losses by leaching and to enable more efficient N use efficiency in crops. The objective of the present work was to study the effect of DMPP on the mineral N (NH₄⁺- N and NO₃^--N) content in soil and water leaching, and physiological characteristics of rose plants. A greenhouse experiment was performed for 10 wk. Four-year-old ‘Charlotte’ rose cultivars grafted on ‘Natal Briar’ were grown in soil and fertirrigated daily with a complete nutrient solution containing 170 mg N L^-1. Two N fertilizers (uncoated urea [UA], and urea + 1% DMPP [UDMPP]) were used. Results showed that UDMPP did not show any advantages on dry mass accumulation, N use efficiency, leaf area, number of marketable stems, SPAD readings, chlorophyll fluorescence, and leaf N concentration. Despite all these results, the addition of the inhibitor reduced mean NO₃^--N concentrations in the percolated water by 65.81%. These results suggest that UDMPP could be a valuable tool to reduce NO₃^--N leaching losses by retaining applied N in the ammoniacal form.

Keywords
Chlorophyll fluorescence, leaf nitrogen concentration, nitrate leaching, nitrogen use efficiency