Nitrate leaching and nutrient status in two irrigation and nutritional management systems in avocado (Persea americana Mill.)

Nitrogen fertilizer is the main nutrient that is used in the avocado orchards of Michoacan, Mexico. Fertilization applied in July and October agrees with the rainy season so that losses of nitrogen (N) may increase and thereby probably decrease the efficiency of its use, and a likely contribution to environment pollution. Therefore, two systems of water management on nitrate leaching and the effect of foliar nutrition were evaluated. The experiment was conducted in an orchard of avocado (Persea americana Mill) cultivar Hass 10 years old. The measurements period was from January 2002 to December 2006. Treatments were fertilization by micro drip irrigation (RL) and traditional irrigation hose (RT). RL was irrigated from 200 to 500 L of water every 8 days depending on the season, while RT was irrigated every 18 to 21 days by filling 3/4 of the bowl to the way the producer. Fertilization was 220 kg N/h/yr in both treatments. Each treatment was evaluated in four trees, each tree taking every day as a repetition. The N-NO sub(3) concentration was monitored at three depths 30, 60 and 90 cm and two stem distances 2.0 and 3.0 m, with suction tubes in each tree. Results indicated that RT leached each year from 80 to 96 mg/L N-NO sub(3) against RL, which produced only 36 to 47 mg/L: the N concentration in leaves was higher in RL with 2.53% N against 2.20% in traditional irrigation.Original Abstract: El fertilizante nitrogenado es el principal nutrimento que se emplea en las huertas de aguacate en Michoacan, Mexico. La fertilizacion aplicada en julio y octubre coincide con las lluvias por lo que las pdrdidas de nitrogeno (N) se pueden incrementar, probablemente tambien disminuir la eficiencia de su uso y contribuir a la contaminacion del ambiente. Para comprender mejor estos fenomenos se evaluaron dos sistemas de manejo de agua en la lixiviacion de nitratos y la nutricion foliar de esta especie. El experimento se realizo en una huerta de aguacate (Persea americana Mill.) cultivar Hass de 10 anos de edad, establecida en un suelo de propiedades andicas. El periodo de mediciones fue de enero 2002 a diciembre 2006. Los tratamientos fueron: fertirriego localizado por microaspersion (RL) y riego tradicional por manguera (RT). En RL se rego de 200 a 500 L de agua cada 8 dias dependiendo de la epoca, mientras que en RT se rego cada 18 a 21 dias hasta llenar 3/4 del cajete a la manera del productor. La fertilizacion fue de 220 kg de N/ha/ano en ambos tratamientos. Cada tratami