| Abstract: | Fertilization with four controlled release nutrient formulations, Sierra 17-6-10, Sierrablen 18-7-10, High N 24-4-8, and Osmocote 18-6-12, was evaluated for its capac ity to facilitate development of containerized singleleaf pinyon (Pinus monophylla Torr.& Frem.) planting stock. A water-soluble fertilizer treatment using Peters 20-10-20 and nonfertilized seedlings provided for comparisons of nutrient amendment effects on growth and nutrition , and each fertilizer formulation was applied using low , medium , and high rates . After 24 months , the high application rate of the Peters formulation produced the largest seedlings overall . Among controlled release treatments , the Sierra formulation applied at the medium rate resulted in the great est shoot dimensions , although the low rate of this fertilizer produced the greatest combined shoot and root dry weight . All treatments resulted in low shoot / root ratios with the exception of the high application rate of Sierra 17-6-10 . Overall , fertilized seedlings exhibited high foliar concentrations of N , P , and K but low concentrations of Ca , Mg , Fe , Mn , Zn , and B relative to nonfertilized seedlings . Foliar S was low in all seedlings relative to documented standards for containerized conifers , while Cu was unaffected by treatment . Among fertilized seedlings , moder ately high N uptake coupled with high P generally resulted in the greatest stimu lation of seedling growth . These results indicate that controlled release fertilization , a method particularly well suited to smaller , less mechanized nurseries , can facilitate the production of containerized singleleaf pinyon with careful selection of nutrient formulation and application rate, but that a production period of 2 years is required to grow planting stock with desired attributes. |
