Fertigation of pepper using urban recycled water

As a consequence of increasing water demand, the lack of natural water resources, and the use of high amounts of fertilizers in the greenhouse crops in Mediterranean area, the use of reclaimed municipal wastewaters represents a valuable option

Fertirrigation NK of pepper using urban recycled water
Dr. MARIA L. SEGURA
Institute of Research and Training in Agriculture and Fisheries (IFAPA), Junta of Andalusia. Camino San Nicolás n.1. 04745 La Mojonera. Almería (SPAIN)
Mail: marial.segura@juntadeanducia.es

As a consequence of increasing water demand, the lack of natural water resources, and the use of high amounts of fertilizers in the greenhouse crops in Mediterranean area, the use of reclaimed municipal wastewaters represents a valuable option, although the knowledge of plant nutritional requirements (N, K, etc.) becomes yet more important in order to avoid the unbalances caused for the nutrient charge present in reclaimed wastewater and to attain efficient nutrient use. The research reported here indicates the influence of different levels of N and K supply applied by fertigation with reclaimed municipal wastewaters (pH: 8.3 and EC: 2.11 dS m-1) on yield, nutrient uptake and distribution in pepper.
Pepper (var. Aifos) plants were grown from August 2007 to January 2008 in a polyethylene greenhouse at the Institute of Research and Training in Agriculture (IFAPA), Almería (southeast Spain). Peppers plants (var. Aifos) were transplanted on August 2007 with a plant density of 2 plants m-2 and ended on 23 January 2008, lasting 155 days. They were grown on a sand-mulched sandy loam soil and fertigation. Five treatments were applied: control (N0K0) no contribution NK fertigation only applied by the irrigation urban recycled water (contribution of 46 kg N ha-1 and 23 kg K ha-1) and four different doses of NK as the mean elements with possible unbalances: N1K1, N1K1.5, N1.5K1 and N1.5K1.5.
N1K1: contribution of 125 kg N ha-1 and 193 kg K ha-1 (average nutrient concentrations in fertigation of 9.8 mM N and 5.4 mM K).
The unfertilized control treatments (N0K0) showed a low commercial production (figure 1), high rates of nutrient application (N1K1.5, N1.5 K1 and N1.5K1.5) resulted in higher total marketable yields that the N1K1 treatment but showed no significant differences between the high rates. Nutrients uptake by the plant followed the same order in all treatments K> N> Ca> Mg> P (g m-2). The period of largest extraction of nutrient by plant occurred from 114 o 155 DAT (harvesting period). The extraction of N and K during this period as a percentage of the total ranged between 57% and 64% according to fertilizer treatment. Plant nutrient distribution showed that fruit is the largest sink of N, K in all the cases: 39–45% of N, and 40–47% of K (figure 2), according to the treatments.

Taking into account the results obtained of nutrient uptake by the plant, the NK rates to be applied in sweet peppers, could be lowered significantly to levels of N1K1 during vegetative growth (28 kg N ha-1 and 45 kg K ha-1 ), flowering and early fruit development periods (34 kg N ha-1 y 50 kg K ha-1), ripening and early harvesting (13 kg N ha-1 and 7.4 kg K ha-1) and the N1K1.5 rate (118 kg N ha-1 and 168 kg K ha-1) for harvest period. This guideline can be considered as an adequate and sustainable procedure to grow greenhouse peppers.