DETERMINATION OF WATER RETENTION CHARACTERISTICS OF PERLITE AND PEAT

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.