The Fate of Soil-Applied Nitrogen in the Fig Tree

Abstract

The timing of nitrogen fertilizer application in an orchard can determine the amount of nitrogen (N) absorbed, distributed, and accumulated in fig tree organs. This study aimed to evaluate the fate of nitrogen (N) applied to the fig tree at different times in the soil. The experiment was conducted in the 2009–2010 crop season. The planted trees belonged to the cultivar Roxo de Valinhos, in the São João Del Rei municipality of Minas Gerais state (MG), Brazil. The treatments were the application of 20 kg N ha−1 as urea, enriched with 2% excess 15N atoms, on September 30 (T1) or on October 30 (T2). In January 2010, the fig trees were cut down and separated into fruit, leaves, new shoots and shoots from previous years, and the stem. The harvested parts were dried, weighed, and ground. Soil was collected from the 0.00–0.10 and 0.10–0.20 m layers, dried, and ground. The total N and excess 15N atoms in the organs and in the soil were determined, and the N derived from the fertilizer was calculated. The annual organs of the fig tree, including leaves, fruit, and young shoots, exhibited the highest accumulation of N from soil application at both timings, with similar N uptake and accumulation levels. However, nitrogen fertilization had a minimal contribution to the overall nitrogen content in young trees and did not exceed 11%. Understanding the fate of nitrogen derived from fertilizer within the fig tree’s organs will allow for more precise adjustments when recommending nitrogen doses.