Surfactant and irrigation impacts on soil water content and leachate of soils and greenhouse substrates

Abstract Water retentionx is considered an important characteristic for determining the efficiency and effectiveness of soils and greenhouse substrates. Surfactants have the potential to improve water infiltration and distribution uniformity throughout the soil profile. In addition, efficient irrigation can improve the wettability of soils. The objective of this study was to determine how surfactants and irrigation influence soil water content (SWC), leachate volume, and pH in soils and greenhouse substrates. This study was conducted at Clemson University, SC, on two soils (sandy loam and sand) and two substrates (Fafard 3B‐SURF and 80% sand, 20% peat). Four surfactants (a) 10% oleic acid esters of block copolymers (OAC), (b) 30% alkoxylated polyols and 21% glucoethers (APG), (c) 50% nonionic polyols and 5% 1,2‐propanediol (NIPP), and (d) water control (CNT) with two irrigation regimes (ONCE and SPLIT) were applied to PVC columns. Based on the leachate results, applying irrigation volume as SPLIT in conjunction with using a surfactant reduced leachate up to 75%. The soils retained more water when OAC and NIPP surfactants were applied. When the soil was left to dry out, the SWC was 5 and 9% higher from SPLIT irrigation compared with ONCE irrigation in the sand–peat and the sand soils, respectively. Surfactants can increase SWC, and combining split irrigation with surfactants can play an important role in reducing leaching from soils and greenhouse substrates, resulting in water quality and quantity conservation, and an economic advantage to the grower.