Rain-fastness and puncture resistance of biodegradable horticultural hydromulches

Abstract

In horticultural production, mulching is vital for suppressing weeds, optimizing the soil micro-climate, and promoting crop growth. Traditional polyethylene-based mulches, despite its effectiveness, poses environmental challenges due to poor recyclability and persistence in ecosystems. Biodegradable hydromulches (HM), composed primarily of cellulosic materials and tackifiers, offer a sustainable alternative. This study evaluated various HM formulations to identify those with optimal moisture resistance through rain-fastness index measurement and puncture resistance. Formulations incorporated fibrous materials, such as paper, wood fiber, hemp hurds, or combinations thereof, blended with tackifiers—guar gum, psyllium husk, or camelina meal at 2 %, 4 %, or 6 % concentrations. Moisture characteristics were assessed for puncture resistance at four moisture levels, 0 %, 50 %, 75 %, and 100 % and rain-fastness. Puncture resistance was measured as the pressure level at which a flat 13.7 mm diameter probe ruptured the formulation. Rain-fastness, a measure of the resistance to material loss under simulated rain, was calculated as the ratio of weight of HM before and after rain-fastness tests. Results showed HM puncture resistance decreased significantly with increased moisture, dropping below 0.50 MPa at 50 % moisture content. Rain-fastness and following puncture resistance tests indicated that paper-based HMs resisted disintegration better than wood fiber-based ones, achieving a higher rain-fastness index and up to 67 % increase in puncture resistance compared to wood fiber formulations. Hemp inclusion decreased puncture resistance by 40–70 %, depending on the tackifier. Formulations with psyllium husk maintained higher puncture resistance than those with camelia meal and guar gum. Paper-based HMs had minimal material loss during simulated rainfall, with a rain-fastness index (RFI) of 0.93, superior to wood fiber formulations' RFI of 0.84. Adding hemp increased material loss by 2–4 %. Overall, paper-based HM formulations demonstrated superior performance, with the top formulations containing paper and varying concentrations of guar gum, psyllium husk, and camelina meal. These findings suggest that paper-based HMs are a promising biodegradable alternative suitable for organic farming but require further field testing.