Fertilizer Absorption Efficiency δ15n -labelled Applied to Maize Crop (Zea Mays) in Central Chile.

Abstract: Nitrogen stable isotopes (δ15N) help to understand the nitrogen (N) uptake in different crop parts. This study investigates the contribution and distribution of N absorption within the different fractions/organs (leave, stem, root and grain) of the crop plant (Zea mays), and labelled N remaining into the soil (0–50cm). An experiment was carried out in an Inceptisol soil type located at Botalcura (35º 18’ 26” S; 71º 47’ 22’’W), a rural area at Maule region, Central-Chile. Three microplots of (2.5m x 1m) were fertilized with urea (NH4)2SO4 tagged with δ15N (10% excess atom) and three intercalated microplots were located as controls. Treatments were control, 50, 100, 100 and 100 kg N ha−1. Results indicate that on averages the maize store N in the leaves with 333 kg N ha−1 and less of 106 kgNha−1 came preferably from the root. From 350 kg N ha−1 as an applied fertilizer to the studied microplots, 6.3% was recovered from the leaves, 6.8% came from the stem, 7.1% came from the root, and 9% came from grain. However, most of the N store in the organs plant came from the soil reaching 409 kgNha-1 in stems and grains. Therefore, considering the recovery efficiency of N in the plant and soil a total of 95.3%; 100%; 30.3% and 100% were stored for leave, stem, root and grain, respectively. This study demonstrates the recovery efficiency of N from the fertilizer is moderate to low and remained N from the soil widely supplies the demand of the plant.