Application Of Urea Coated By Humic Acid and Nitrogen Inhibitor On Pre Nursery Phase Oil Palm (Elaeis guineensis Jacq.) Seedling

Abstract

Nitrogen is one of the essential nutrients for plant growth, especially for oil palm. However, nitrogen fertilizer application from urea would likely result in losses in the soil due to leaching, volatilization, and immobilization by soil organic matter, which can cause nutrient unavailability for plant uptake. Humic acid and nitrogen inhibitors are believed to be two of the ameliorants that can increase nitrogen availability for plant uptake. The research aimed to evaluate the use of urea coated with humic acid and nitrogen inhibitors on the growth, biomass, and nitrogen efficiency of oil palm seedlings in the pre-nursery phase. The experiment was conducted in the Indonesian Oil Palm Research Institute's greenhouse in Bogor. The experimental design was a factorial randomized complete block design with three replications. Factor 1 was the type of fertilizer, consisting of a) urea, b) urea + humic acid, and c) urea coated with humic acid. Factor 2 was the type of nitrogen inhibitor, consisting of a) without inhibitors, b) urease inhibitor, c) nitrification inhibitor, and d) urease and nitrification inhibitor. The results showed that in the type of fertilizer factor, urea coated with humic acid increased plant height, number of leaves, stem diameter, leaf area, chlorophyll content by SPAD value, root length, root volume, fresh weight of shoot and root, root dry weight, nitrogen utilization efficiency by fertilizer, partial factor productivity, and partial nutrient balance. In the type of nitrogen inhibitors factor, urease inhibitor only increased plant height at 4 months after planting. The combination of urea coated with humic acid and urease inhibitors increased plant height at 4 months after planting and root dry weight.