Biosolarization: harnessing the sun and organic matter for weed control

Biosolarization is a new innovation in the realm of weed control. Different from the commonly known practice of solarization, which uses clear plastic sheeting on moist soil to thermally terminate a variety of pest species, biosolarization includes the use of organic matter in the form of compost, cover crops, manure or other materials such as pomace or nut hulls. The addition of organic matter can accelerate the process by encouraging anaerobic soil disinfestation. The carbon from organic material produces chemicals with bio-pesticidal activity. The combination of these natural chemicals and heat acts like a fumigant and eliminates soil-borne pests and weed species. 

The primary objective of this project is to measure the efficacy of biosolarization on weedy species populations present on three organic farms in the Sacramento Valley of northern California (Solano and Yolo Counties). This trial will be replicated on each farm. Each farm will have three replications of three treatments. There will be a solarized treatment, a biosolarized treatment using compost, and a control. The biosolarized treatments will be covered for 8-10 days after incorporating the compost and the solarized treatments will be covered 32 days, which is the minimum recommended time for solarization in the Central Valley. 

We expect the biosolarized plots to significantly reduce weed populations, both in absolute number and species present, compared to the control plot. When compared to the solarized we expect the biosolarized plot to take less time to achieve equal or better weed control.