Agriculture & Forestry, Vol. 64 Issue 3: 113-126, 2018, Podgorica 113 DOI: 10.17707/AgricultForest.64.3.10 Vesna MARKOSKA, Velibor SPALEVIC, Kiril LISICHKOV, Katerina ATKOVSKA and Rubin GULABOSKI DETERMINATION OF WATER RETENTION CHARACTERISTICS OF PERLITE AND PEAT SUMMARY The results of the water retention curves between (pF -2 and -4.2) matric potential for two substrates perlite and peat, are presented in this paper. Perlite is an inorganic, expanded aluminosilicate of volcanic origin. Peat is an organic substrate. For assessing this parameter, the method of bar extractors and Porous plate extractors have been explored. The method is applied on 7 different regimes of pressure (0.1; 0.33; 1; 3; 6.25; 11; 15 bars) in samples composed of perlite and peat present at different volume ratios of 80% Perlite + 20% Peat, 70%Perlite + 30% Peat, 50% Perlite + 50% Peat, 30% Perlite + 70% Peat, 20%Perlite + 80% Peat. The retention capacity of the pеrlite, at all applied different point of tension, is: 67.88% for 0.1 bar, 58.35%, for 0.33 bar, 47.70% for 1 bar, 39.78%; for 3 bars, 34.84 for 6.25 bars, 30.10% for 11 bars and 26.65% for 15 bars and for the peat are: for 0.1 bar = 89.16%, for 0.33 bar = 74.84%, for 1 bar = 57.94%; for 3 bars = 45.15%; for 6.25 bars = 39.57; for 11 bars = 33.89%; for 15 bars = 23.17%. The peat substrate shows higher retention at all points of tension of 0.1; 0.33; 1; 3; 6.25; 11, with the exception of 15 bars, when the retention is lower than the substrate perlite. The reason for the higher water retention at peat than at perlite, is the result of the high content of the humus in the peat. Of all the analyzed samples, it can be seen that all curves show a favorable water retention capacity, which is due to the fact that the peat and the perlite as substrates have high porosity. The aim of this paper is to examine the impact of the water retention capacity of both substrates and their mixtures. Also to see the ability which substrate retains a greater amount of water that will be easily accessible to the plants for their proper growth and development. Key words: perlite, peat, water retention. 1 Vesna Markoska (corresponding author: vesnemarkoska@yahoo.com), Faculty of Environmental Resources Management, MIT University, Skopje, MACEDONIA. Velibor Spalevic, University of Montenegro, Faculty of Philosophy Niksic, Department of Geography, MONTENEGRO; Kiril Lisichkov, Faculty of Technology and Metallurgy, University Ss. “Cyril and Methodius” Skopje, Republic of Macedonia. Katerina Atkovska, Faculty of Technology and Metallurgy, University Ss. “Cyril and Methodius” Skopje, MACEDONIA, Rubin Gulaboski,Faculty of Agriculture, Faculty of Medical Sciences, University "Goce Delcev" Stip, MACEDONIA; Notes: The authors declare that they have no conflicts of interest. Authorship Form signed online.