Effect of different fertilization strategies on nitrogen balance in an outdoor potted crop of Osteospermum ecklonis (DC.) Norl. ‘Purple Red’ under Mediterranean climate conditions

Abstract

Fertilization management and meteorological conditions can affect leachate composition and the balance of nitrogen (N) added during the cultivation of ornamentals. The main objectives of this study were to estimate the N balance components and to establish relationships between the N concentration in leachates and meteorological variables when different fertilization strategies are used in an outdoor potted crop of Osteospermum ecklonis (DC.) Norl. ‘Purple Red’. Two fertilizations strategies, i.e. continuous fertigation (NS) and incorporated controlled-release fertilizer (CRF), were applied to the crop. The treatments were two NS doses (NO3 –-N concentration in each NS, NS-A: 154 mg L–1 and NS-B: 112 mg L–1) and two CRF doses (CRF-C: 5.0 g L–1 of substrate and CRF-D: 2.5 g L–1 of substrate). The N loss by leaching was higher in the NS-A treatment than in the other ones (1.1 g pot–1, 11% of total available N). The amount of N accumulated by the plants was higher in the NS treatments than in the CRF treatments (average 2.5 g pot–1, 29.5% of total available N). However the efficiency of use of N was the greatest in the CRF-D treatment (23.9 g dry matter produced g–1 N supplied). About 50% of the total available N was measured in the substrate in all treatments (average 3.8 g pot–1). The concentration of N in the leachates for the two CRF treatments did not correlate with the substrate temperature or precipitation. The N released from the CRF matched the nutritional requirements of the plants better than the N applied by continuous fertigation.