Nutrient Balance in Hass Avocado Trees as a Tool to Optimize Crop Fertilization Management

Abstract

This study was conducted to evaluate fertilization management based on fruit nutrient removal, soil nutrient-supplying capacity and tree nutritional status with standard nutrient values as a reference and the effects on fruit size and yield in Hass avocado trees. The soil chemical characteristics, foliar nutrient content interpreted with the Kenworthy balance index (KBI) method and fruit nutrient removal for a planned yield of 20 ton/ha were used to determine the fertilization management plan for the crop. The experimental area had soils with Andic characteristics and sandy loam texture, low cation exchange capacity and acidic pH. The farmer’s standard fertilization plan was based on excessive fertilizer doses for N, P, K and Ca, and an imbalance of P, Ca and micronutrients was observed with the diagnosis of plant nutrient status. The fertilizer plan based on the KBI method had an effect on yield variables in the second crop year, with an increase in production of 20 kg/tree as well as an increase in the percentage of fruits with a size higher than 22 (165–196 g/fruit) according to the Codex Alimentarius standards. These findings indicate that the reincorporation of minerals extracted by the harvest into the soil and the plant nutrient status are useful tools to guide crop fertilization management when fine-tuned to local soil chemical conditions and crop requirements to minimize nutrient losses.