The effect of hydrogel additives on the water retention curve of sandy soil from forest nursery in Julinek

Forest nurseries are mostly located in light and very light sandy soil sites. They are characterised by low water holding properties in the aeration zone, and their water resources depend mainly on precipitation. One of the possible ways to solve this problem is to use hydrogel additives to soils. The objective of this study was to investigate the influence of polyacrylamide SuperAbsorbent Plus on water retention curve of a sandy soil from forest nursery in Julinek. Surface soil layer (15 cm deep) was collected for experiments. It was mixed and divided into 5 parts. Each part, except control, was enriched with hydrogel additives in the amount of 0.5, 2, 4, and 6 g·dm –3 . Six samples were taken from each soil part with hydrogel treatment and from control soil (without hydrogel). Water retention was measured with the Soil Moisture Equipment Corporation (Santa Barbara, California, USA) – LAB 012 in Agrophysics Institute in Lublin. Results of soil moisture at particular water potential values were shown as pF curves, and the analyses of soil retention properties were performed for particular pF ranges adopted after WALCZAK et al. (2002). Soil treatment with hydrogel increased soil retention properties, mainly in the range of pF less then 2.0. The largest increase of retention capacity was found in the range of pF 0–2.2. It means that hydrogel accumulates the gravitation water in the soil, which under natural conditions rapidly permeates the soil profile and becomes unavailable