Effect of using slow release N and humic substances as partial replacement of inorganic N on growth and nutritional status of Bartemuda date palms

摘要

This study was undertaken during 2016 & 2017 seasons to examine the effect of reducing inorganic N partially by using some slow release and humic fertilizers on some vegetative growth aspects, leaf photosynthetic pigments and N, P, K and Mg in the leaves of Bartemuda date palms grown under Aswan region conditions. Three slow release N fertilizers namely urea formaldehyde (UF) sulphur coated urea (SCU) and phosphorus coated urea (PCU) were used at 20 to 60 %from inorganic N as well as humic and fulvic aids were applied at 20 to 60 ml/ palm. Replacing 60- 80 % inorganic N partially by using 20 to 40% any slow release N fertilizers ( UF, SCU or PCU) or 20 to 40 ml humic or fulvic acids had an announced promotion on all growth characteristics relative to the use of Nas 100% inorganic N form. Using inorganic N as 40% besides any one of the there slow release fertilizers at 60% or humic and fulvic acids each at 60ml / palm caused an obvious reduction on these growth, aspects. Reducing inorganic N percentages growth from 100 to 40% and at the same time enhancing percentages of the slow release N fertilizers from 0.0 to 60% and both humic and fulvic acid levels from 0.0 to 60 ml / vine caused a gradual promotion on chlorophyll a & b, total chlorophylls, total carotenoids N, P, K and Mg. The minimum values of these leaf chemical components were recorded on the palm that received N as 100% inorganic N. For enhancing growth and tree nutritional status of Bartemuda date palms, it is necessary to fertilize the palms with N ( 1000 g / palm/ year) as 60 % inorganic N + 40 ml humic acid per palm/ year.