Hydroxyapatite-Carboxylated Cellulose Nanocrystals and Urea: Effects on Nitrogen Management and Tomato Growth

Effective nitrogen management is of paramount importance for achieving high tomato yields, given its role in promoting growth and biomass production. The use of slow-release fertilizers (SRFs) is crucial for the reduction of nitrogen loss through leaching and volatilization, thereby mitigating the risk of water pollution and eutrophication. The objective of this study is to evaluate the impact of a novel sandy loam soil treated with slow-release fertilizer pellets comprising hydroxyapatite (HAP) and carboxylated cellulose nanocrystal (CNCCA) composites on tomato growth. Greenhouse pot experiments were conducted using urea (U), HAP-U, HAP-CNCCA-U, and control treatments under normal irrigation conditions. The slow-release fertilizers resulted in a notable enhancement in plant growth parameters, including height, stem diameter, number of leaves, chlorophyll content, fresh weight, and dry weight, in comparison to the untreated soils (P < 0.05). The HAP-CNCCA-U treatment demonstrated a 32% increase in fresh biomass and a 26% increase in dry biomass in comparison to the urea treatment. The slow-release results indicated that the nitrogen release was prolonged, with a cumulative nitrogen release of 31% from HAP-CNCCA-U within 6 days, in comparison to the complete release observed with urea. These findings illustrate the potential of HAP-CNCCA-U as an effective nitrogen management system for sustainable tomato cultivation.