OPTIMIZATION OF OVERHEAD IRRIGATION IN RELATION TO IRRIGATION WATER USE EFFICIENCY IN THE LOUISIANA NURSERY INDUSTRY

Irrigation efficiency is an essential component of nursery production in the United States. To increase productivity of Louisiana growers, a series of studies were conducted to evaluate current nursery water practices. The objectives were to determine current irrigation practices; evaluate actual water usage; and compare nursery media for water utilization. A mailed survey determined that the majority of growers used can yard production (63%), overhead irrigation (79%), had no irrigation manager (82%) and did not collect/reuse water(61%); 50% do not test/calibrate their irrigation system. Based on this information, five nurseries using overhead irrigation were selected to determine water application and the attributes of their potting media. These results indicated that overall, less water was being applied than perceived; localized irrigation was highly variable within a nursery and even within a single production yard. Irrigation within all nurseries averaged 0.29”/A of water and had a range of 0.37”/A. Within a single nursery a range from 0.17 to 0.53”/A was found between three different can yards. Within a single yard a range of 1.0”/A difference (0.5 to 1.5”) was found. Water holding capacity (WHC) for all evaluated nurseries were tested and determined that only 17% of nurseries fell within the target range of 45-65% WHC. Another 17% fell within 10% and the remaining 66% were greater than 10% from the target WHC. This information was used to evaluate water stress on two crops, Lantana x \u27Monine\u27 Spreading Sunshine® and Plectranthus scutellarioides \u27Alabama\u27, using three watering equivalents for acre inches: a low (0.5”) and standard (1.0”) and high (2.0”) watering treatment. This was conducted for 42 days and resulted in no significant differences in biomass for roots or shoots in coleus. However, lantana shoot biomass in the high water allocation was found to be statistically less than normal and low application for root biomass in the lower irrigation application where shown to be statistically lower than the 1.0 and 2.0 applications. Market quality decreased for 0.5 and 2.0 applications