Addressing Agricultural Mulch Challenges in Specialty Crop Production

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.Advisor: Sam Wortman