Addressing Agricultural Mulch Challenges in Specialty Crop Production
Wehrbein, C. D.. 2025.
Abstract
Agricultural mulches are an essential yield-boosting tool in modern specialty crop
production that provide weed suppression, temperature modulation, and moisture
conservation functions. Polyethylene plastic mulches are the most widely used
agricultural mulch but are not sustainable given their pollutive effect on the environment
and challenges associated with recycling. In order to move towards a more sustainable
industry, plastic mulch use in agriculture should become more efficient or replaced with
more environmentally friendly alternatives. Biodegradable mulches may be a suitable
alternative to plastic mulch, but they are often less durable and prematurely degrade in
field conditions. Considering this, my dissertation research aimed to explore viable mulch
technology and production techniques that promote biodegradable mulch use or reduce
plastic use in specialty crops. Research topics that were investigated include a novel
direct seeding technique onto biobased polylactic acid (PLA) mulches, double-cropping
strawberry into plastic mulches, and the integration of cover crops into plastic mulch
systems.
We found PLA mulches to be effective at providing high levels of weed
suppression in direct-seeded carrot and lettuce production when combined with a
compost topdressing. PLA mulches that contained fertilizers did not prematurely degrade
and were suitable to suppress weeds, but the inclusion of fertilizers did not increase soil
nitrogen in response. While PLA mulches are useful in dense crop plantings, we find
fertilizer-enriched PLA to have minimal utility in these cropping systems. From our
double-cropping research, strawberry establishment was not hindered by plastic mulch
thickness (despite the lower durability in 1 mil plastic mulch), demonstrating that plastic
use can be further reduced by using 1 mil mulches rather than 1.5 mil mulches. We also
found the type of fertilizer and summer crop preceding the strawberry crop can affect
strawberry yields, indicating the need for different fertilizer strategies depending on the
previous crop demands and the residual activity of the fertilizer applied. Finally, we
explored the concept of using cover crop windbreaks to improve biodegradable mulch
durability and enhance crop productivity. Windbreaks were effective at reducing southern
windspeeds on adjacent mulches and increasing bioplastic durability. Improved
microclimate conditions were also found to enhance bell pepper yields
