Environmental degradation and efficacy of a sprayable, biodegradable polymeric mulch

Polyethylene (PE) and other non-degradable plastics are used in vast quantities as agriculture mulch to help protect the soil surface, conserve water, and improve soil microclimatic factors. Unfortunately, their continued use poses several environmental problems, so an environmentally friendly solution needs to be found. The use of biodegradable plastics in place of conventional PE is one well studied solution, and here we investigate how different controlled environmental conditions affect the water conservation efficacy, and rate of biodegradation of a novel, biodegradable, sprayable polycaprolactone based polyurethane mulch. The effect of soil moisture content, sunlight, soil type, and polymer pigmentation are investigated using several different characterization techniques and measurements. It was found that the polymer studied is effective at conserving soil moisture, and that it biodegrades at different rates via a bulk erosion mechanism. The rate at which it degrades mostly depends on the soil type to which it is applied, and the moisture content of that soil. This was confirmed using soil CO₂ emissions, polymer mass loss, polymer molecular weight reduction, and scanning electron microscopy. Results are discussed.