The Effect of Nitrogen Fertilizer on the Growth and the Yield Characteristics of Spinach

Abstract

This study analyzes the impact of different nitrogen fertilization levels, in the form of UREA, on the growth and yield of spinach (Spinacia oleracea L.) under greenhouse conditions in Raška during the 2022 and 2023 growing seasons. The experiment was set up using a Randomized Complete Block Design with three replications, on a 12 m2 plot. UREA (46% N) was applied in various rates (0, 40, 80, 120, and 140 kg ha-1) to evaluate its effect on spinach growth and productivity. Key parameters such as plant height, days taken to first cutting, number of leaves per plant, leaf length, fresh weight of leaves, and yield per pot and hectare were measured. The results showed significant differences in most of the analyzed parameters. As the N rate increased, plant height, number of leaves per plant, leaf length, and yield increased, with the highest values recorded at 140 kg ha-1. However, excessive doses showed diminishing returns, particularly between 120 kg ha-1 and 140 kg ha-1. The control group exhibited the lowest values for all parameters. Additionally, earlier flowering and potentially reduced quality with higher nitrogen doses were observed. The study concludes that optimal nitrogen levels are crucial for spinach yield and quality, and a balanced approach to fertilization is necessary to achieve sustainable production while minimizing environmental risks.