Comparison of the effect of perlite and vermiculite on 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-A1B climate change scenario, a considerable decrease in soil moisture in May-August is foreseen for Lithuania in the future. Compared with 1971-2000, soil moisture for as soon as 2001-2030 has been projected to decline 15-18%. The greatest changes are expected in western, as well as north-eastern Lithuania (nation wide at 15.9%). The use of biological 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, when 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 in laboratory conditions, the second at the water balance research site of the Water Resource Engineering Institute (field conditions). After experimenting with a mixing substrate in different proportions with vermiculite, it was found that, at 20°C, the retention of the absorbed moisture content is dependent on the amount of the 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 the substrate and perlite, all soil moisture reserves evaporated after 36 days. The tendency that a higher number of moisture-retaining additives leads to higher yields was not determined, vice versa - to grow larger onion heads it is enough a small (1 cm) thick of biological additives.