Comparison of the effect of perlite and vermiculite on the moisture retention

Abstract

Due to unfavourable weather, Lithuanian farmers suffered losses in 2000-2014, which amounted to an average of about 5% of total crop production. According to the HadCM3-AlB climate change scenario, considerable decrease in soil moisture in May-August is foreseen in Lithuania in the future. Compared with 1971-2000, soil moisture for as soon as 2001-2030 is projected to decline 15-18%. The greatest changes are expected in western, as well as north-eastern Lithuania (nationwide at 15.9%). The use of additives to the cultivation of agricultural products, particularly germination and rooting periods, can ensure the required moisture content of the soil. The use of additives is more economical growing relatively more expensive raw materials, so in most cases it is related to vegetable and berry crops. The study was carried out in two stages: the first stage was carried out under laboratory conditions, the second at the Water Resource Engineering Institute's water balance research site (field conditions). Accrued soil moisture change was recorded every 24 hours by weight. Laboratory test conditions were also carried out by means of environmental chambers monitored 24 hours a day set at 17 °C, 19 °C, and 20 °C. During the field experiment evapotranspiration was established with the help of weighed evaporators every 5 days. Evaporation rate was determined via the water balance method. Experimenting with mixing substrate in different proportions with vermiculite it was found that, at 20 °C, the retention of absorbed moisture content is dependent on the amount of vermiculite in the mixture (the retention of moisture reserve effect is +9 days). Perlite was the most effective at 20 °C with 50:50 ratio of substrate and perlite, all soil moisture reserves evaporated after 36 days. [...]