Fertigation versus conventional nitrogen fetilization of "Valencia" oranges

Abstract

An experiment was carried out during four years, comparing conventional fertilization by broadcasting (CONV) with nitrogen fertilizer (urea) versus fertigation (FERT), in a mature "Valencia late" orange grave. For both methods of application, three different rates were used (LOW, MEDIUM, HIGH). LOW was 50 % and HIGH was 150% of MEDIUM rate. Considering equal rates, N level in Ieaves was higher in FERT plots than in the CONV ones. During the research period, to reach the optimum level in Ieaves (2.2% N) 24% more fertilizer was used, ifit was applied by broadcasting instead offertigation. This difference was 84% ifthe goal was to achieve a 2% level in Ieaves. Total yield was significantly higher in two of the four years, and the cumulative fresh fruit yield in the whole period, was 6% higher in the FERT plots than in the CONV ones. However, the average fruit weight was higher one year in the CONV plots than in the FERT plots. Neither the juice quality nor the trunk growth were affected by the mode of application or the rates ofN fertilization.
The application as fertigation, will let us obtain better yields, using substantially smaller amounts of N fertilizer.