Slow-controlled release fertilizers used in nursery seedling productions. Doses and formulations effects on Pinus halepensis Mill. seedling quality

Abstract

The results of applying three doses of coated slow release fertilizers OSMOCOTE 9-13-18 (1.5; 3.25 and 5 g/l) and OSMOCOTE 16-8-9 (3.25; 5 and 7 g/l) in producing Pinus halepensis seedlings are evaluated. Mixing the fertilizer in the growing media increased the salinity, but didn’t affect the germination and survival of the seedlings. N and P leach concentrations were correlated with the application rates, but K wasn’t. N, P and K shoot concentrations at lifting were correlated with the doses applied, although the relationship between K and doses was the weakest. Shoot growth responded significantly only to N doses. The relative N proportion in OSMOCOTE 9-13-18 was deficient, and OSMOCOTE 16-8-9 had a K deficient ratio, due to the dilution effect observed. The mineral nutrient uptake efficiency decreased in response to the dosis, but was higher than observed in liquid fertilizer injection methods.