IRRIGATION REQUIREMENTS, ROOT-MEDIUM PH, AND NUTRIENT CONCENTRATIONS OF EASTER-LILIES GROWN IN 5 PEAT-BASED MEDIA WITH AND WITHOUT AN EVAPORATION BARRIER

Subirrigated Easter lilies were grown in five commercially formulated root media using one water-soluble fertilizer applied independently to each medium based on water-holding capacity and water loss. The number of irrigations ranged from 12 to 20 and the amount of applied water ranged from 5.3 to 6.8 liters for the uncovered media treatments. When the root-medium surface was covered with an evaporation barrier, the average amount of applied water was reduced by 35% compared to the uncovered media. The largest effect on root media pH was between uncovered and covered media due to the reduced amount of water applied. Similar macronutrient concentrations were measured in the five media during the experiment with few exceptions. The greatest differences in nutrient concentrations were found within the pots. The top 2.5 cm (top layer) contained nutrient concentrations up to 10 times higher than those measured in the remaining root medium (root zone) of the same pot. Covering the root-medium surface with an evaporation barrier reduced the stratification of fertilizer salts. Root-zone soluble salt concentrations of plants in the covered pots were similar to those of uncovered plants even though 36% less fertilizer was applied to the covered plants.