Supervisors info:
Σταματάκης Μηχαήλ, Καθηγητής, Γεωλογία-Γεωπεριβάλλον, ΕΚΠΑ.
Μουστάκας Νικόλαος, Καθηγητής, Α.Φ.Π. & Γ.Μ., ΓΠΑ.
Αργυράκη Αριάδνη, Αναπληρώτρια Καθηγήτρια, Γεωλογία-Γεωπεριβάλλον, ΕΚΠΑ.
Summary:
In this study zeolite tuffs of Greek origin with different natural, chemical and mineralogical properties have been studied for their effectiveness as slow release fertilizers (SRF) by successive leaching tests. Six representative samples of Greek zeolite tuff containing four representative species of zeolites (heulandite-clinoptilolite, mordenite, analcite, chabazite), were selected and added to the soil along with the basic fertilizer for the cultivation of olives, which is the most widespread cultivation in the Mediterranean region, in order to assess their soil impact as SRF, as well as soil improvement (pH, Cation Exchange Capacity etc).
The materials selected were from different areas of Greece - the island of Samos (Aegean Sea) two kinds of a chabazite and an analcite, from the island of Kimolos (Aegean Sea) a mordenite, from Orestiada (Northeastern Greece) a heulandite, from Feres (Northeastern Greece) is a mixture which is dominated by clinoptilolite and Kirki (Northeastern Greece) an analcite and were added with two different kinds of soil, one acidic from the Messinia region and one alkaline soil from the Megara region and the results showed that they can be used not only as slow release fertilizers (SRF) but also as soil amelioration.
The following analyses were performed on soil and tuff samples. In the soil samples, specify the Color based on Munsell (Soil Survey Laboratory Methods Manual 2004). Soil texture and Soil acidity pH (McLean, 1982) were then studied along with the Effective Specific Gravity and the Soil Calcium Carbonate (Soil Survey Laboratory Methods Manual 2004). Then the Organic Carbon was calculated using the modified Walkley – Black Liquid Oxidation Method (Nelson and Sommers, 1982) and the Cation Exchange Capacity (CEC) with two methods one fast method lasting one day Soil Survey Laboratory Methods Manual (2004) and one slow method which lasts at least one week (modified Chapman method, 1965). In addition, substitute ions (Soil Survey Laboratory Methods Manual 2004) and the available phosphorus for both Acid Soil (Bray Method of Sample pH <6.5) (Murphy and Riley, 1962) and Alkaline Soil and tuff samples were determined (Olsen Method Sample pH> 6.5) (Olsen and Sommers, 1982). Ions were measured by colorimetric determination of nitrogen, ammonium nitrogen (Indophenol Method) and boron (Azomethine-H Method) based on the Soil Survey Laboratory Methods Manual (2004). The above methods were verified by HACH ammonium spectrophotometric method; the method followed for ammonium is 10031, for nitrate method is 8039 and for phosphate method is 8048. Magnesium ions were measured in atomic absorption with 1% lanthanum and without. Finally, minerals were determined by XRD as well as % composition of the samples by XRF.
The most effective material proved to be the zeolite tuffs from Orestiada and the material from Feres which was a mixture of zeolite and clay minerals montmorillonite. Therefore, it can be concluded that rocks containing clinoptilolite-eulandite type zeolites, or zeolite/montmorillonite mixtures work efficiently in slow release of fertilizers in the above-referenced soil types.
Keywords:
Zeolite tuffs, Slow Release Fertilizers (SRF), Cation Exchange Capacity (CEC), Soil, Olea europaea.
