Abstract

Fertilization and irrigation practices affect water-and nutrient use-efficiencies in container-produced nursery crops. This study was conducted to determine if gravimetric monitoring of a plant-substrate-container unit could manage real-time irrigation volume to achieve a near zero leachate fraction and to study baldcypress (Taxodium distichum (L.) Rich.) growth, nutrient accumulation and water-use efficiency under a factorial combination of two irrigation leachate fractions and two controlled release fertilizer (CFR) rates. Baldcypress plants were grown at either 45 or 90 g of 15N–3.1P-12.5K (15-7-15 Multicote, six-month controlled release fertilizer top dressed on each container), and two irrigation rates, near-zero or 0.2 leachate fraction. Height growth, whole plant dry mass and shoot: root dry mass ratios, and water-use efficiency were not affected by a fertilizer and irrigation interaction. The higher fertilizer rate increased the whole plant N and K concentrations. Relative to a 20% leachate fraction irrigation regime, a near-zero leachate fraction decreased leachate volume and root, shoot and whole plant dry mass, while leachate electrical conductivity (EC), plant tissue mineral nutrient concentrations and water use efficiency increased. Although baldcypress whole plant dry mass was reduced under the near-zero leachate irrigation regime (presumably due to high soluble salt levels) there was no difference in height and stem diameter at the higher fertilizer rate between the two irrigation regimes. The near-zero leachate irrigation regime applied approximately one-half the irrigation volume of the 0.2 LF irrigation regime.