ISHS Acta Horticulturae 700: International Symposium Towards Ecologically Sound Fertilisation Strategies for Field Vegetable Production
EFFECT OF APPLIED N CONCENTRATION IN A FERTIGATED VEGETABLE CROP ON SOIL SOLUTION NITRATE AND NITRATE LEACHING LOSS |
| Authors: | M. Gallardo, R.B. Thompson, J.R. Lopez-Toral, M.D. Fernandez, R. Granados |
| Keywords: | pepper, nitrogen management, greenhouse, intensive horticulture |
| DOI: | 10.17660/ActaHortic.2006.700.37 |
| Abstract:
Pepper was grown, in soil, in two greenhouses using drip irrigation and fertigation. In one greenhouse, the “conventional” treatment, the NO3- concentration in the applied nutrient solution was 10-12 mmol L-1, consistent with local practice. In the other, the “reduced N” treatment, there was a targeted reduction of 20% in the applied NO3- concentration, which resulted in applied NO3- concentrations of 7-9 mmol L-1. In both treatments, the applied NH4+ concentration was 1.5-2 mmol L-1. For 3 weeks, irrigation was given in accordance with local practices, and thereafter using tensiometers (-15 to -25 kPa). Drainage was collected with free-drainage lysimeters. Total amounts of N applied were 194 and 168 kg N ha-1, and of NO3-–N leached were 64 and 61 kg N ha-1; the respective differences were 14 and 7%. Drainage was a major determinant of NO3- leaching; 80% of drainage and NO3- leaching occurred in the first 6 weeks, when only 39% of the N had been applied. After 10 weeks when little drainage occurred, the NO3- concentration in the soil solution at 0.13 m depth was very responsive to the different N management treatments. During this period, soil solution NO3- concentration in the conventional treatment increased considerably, and was 80-144% greater than that in the reduced N treatment, which declined slightly over time. These data suggest that when there is little drainage, tendencies in soil solution NO3- concentration may be useful as an indicator of the adequacy of N nutrition. | |
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