Dissertation

Χρήση κλινοπτιλόλιθου και παλυγορσκίτη ως εδαφοβελτιωτικά στην καλλιέργεια μαρουλιού

Mathioudakis, Alexandros Michail

2025

Overview

Knowledge of the parameters of rational fertilization leads to increased production, improved product quality, reduced environmental impacts, reduced production costs and satisfaction of global food demand.In this master's thesis, two minerals, clinoptilolite and palygorskite, were used in two concentrations in soil, which in combination with chemical fertilizer aim to create slow-release fertilizers of nutrients. Slow-release fertilizers allow the release (release) of nutrients, seeking the controlled release of soil nutrients. In addition, they provide nutrients to plant roots for a prolonged period of time, thus reducing the possibility of water pollution by avoiding nutrient leakage.The materials used for the execution of this thesis are clinoptilolite (zeolite) from Thracean Zeolite®, palygorskite from GEOHELLAS, soil and liquid fertilizer from the ELGO DIMITRA Institute of Chania. In the initial stage, the minerals and soil were ground to a size below 63 μm, followed by mineralogical analysis by X-ray diffractometry (XRD) and chemical analysis by X-ray fluorescence spectrometry (XRF). In addition, for the minerals and soil, pH, conductivity, granulometric analysis by wet sieving and laser granulometry, as well as measurement of cation exchange capacity with the Kjedahl apparatus were carried out in the Geochemistry laboratory of the Technical University of Crete. The next stage of the experimental procedure included column experiments, in which five different samples were placed: soil, soil with 5 g of palygorskite, soil with 2.5 g of palygorskite, soil with 5 g of zeolite and soil with 2.5 g of zeolite, through which liquid fertilizer diluted with water from the network of the Prefecture of Chania was passed. This experimental procedure simulated fertilization and watering in lettuce cultivation and lasted 14 days. In the lettuce experiment, which lasted 19 days, five different samples were placed in pots: soil, soil with 123 g of palygorskite, soil with 246 g of palygorskite, soil with 123 g of zeolite and soil with 246 g of zeolite, through which diluted liquid fertilizer was passed. Photographic material was collected and surface images of the lettuces were taken, in order to calculate the increase in leaf area in each sample. After the completion of the experiments, the concentrations of potassium, magnesium, phosphorus, copper and zinc were determined by atomic absorption spectrometry-AAS (Perkin Elmer Analyst 100 spectrometer), absorption spectrophotometry (Jenway 7315 spectrometer) and inductively coupled plasma emission spectroscopy (ICP-MS) (Agilent 7500cx ICP-MS spectrometer), which belong to the Geochemistry and Hydrogeochemical Engineering and Soil Remediation laboratories of the Technical University of Crete, respectively.According to the results of the experimental procedure, the use of zeolite and palygorskite contributes to the retention and release of nutrients. The application of 246 and 123 g of palygorskite, as demonstrated by the column experiments and the lettuce experiments, releases significant amounts of magnesium from the palygorskite structure, which probably makes the addition of magnesium to the liquid fertilizer unnecessary. On the contrary, 246 and 123 g of zeolite retain quantities of magnesium, making it available to the lettuce roots. In addition, 246 g of zeolite retains more magnesium compared to 123 g. 246 g of zeolite retains a greater amount of potassium compared to the other tests in both the column experiments and the lettuce experiments. The increase in the concentration of the mineral in the soil, for zeolite and palygorskite, leads to an increase in potassium retention. In the column experiment, the minerals release amounts of copper and zinc, while zinc retention is observed in the last days only for the 246 g zeolite. According to the surface growth data, the 246 g zeolite, the 123 g zeolite and the 123 g palygorskite act as soil conditioners, while the 246 g palygorskite may inhibit growth. Enhancing the concentration of zeolite in lettuce cultivation makes sense, as it acts as a slow-release fertilizer, retaining significant amounts of nutrients, such as magnesium, potassium and phosphorus, for an extended period of time, making them available to the plant roots.

• Publisher: ProQuest Dissertations & Theses
• Subject: Biology / Geotechnology / Soil sciences
• ISBN: 9798263315559