Research Highlight: Improving Eggplant Growth and Weed Control with Cover Crops and Biosolarization
This article summarizes the findings published in the journal:
S. Morrissey, N. Chueh, C. Conte, C. Simmons. 2025. Effect of cover cropping and biosolarization on eggplant growth, soil pests, and soil nitrogen, Journal of Agriculture and Food Research 23, 102160. https://doi.org/10.1016/j.jafr.2025.102160.
In a time of increasing interest in sustainable agriculture, continued pest control is necessary to maintain crop production and yield.
Biosolarization is an alternative pest control technique that involves adding organic matter and heating moist soil under a clear plastic tarp. This technique has been shown to control a variety of soil pests, including plant-damaging fungi, nematodes, and weeds due to the increase in soil temperature and products from the breakdown of organic matter. Biosolarization offers an effective alternative to chemical fumigation for soil pest control while reducing pesticide use and associated human health risks.
Cover crops—plants grown between cash crops to add fertility to soil and disrupt weeds and pests—present a potentially convenient, on-farm source of organic matter for biosolarization. However, research is needed to understand how biosolarization with cover crops affects later cash crop growth.
About the study
Researchers in the Simmons Lab at UC Davis studied how biosolarization using cover crops affected the growth of eggplants and weeds following the treatment. The goal was to see whether cover crops could serve as an effective organic material for biosolarization while also supporting strong crop production.
Various cover crops were grown, then mowed and tilled into the soil for the biosolarization treatment. The researchers then planted eggplants in the soil and tracked their growth and fruit production, as well as weed growth to determine how these practices may contribute to crop growth and pest management.
Key findings
Eggplants grown in soils biosolarized with cover crops were significantly larger and produced more fruit than those grown in untreated soil. The researchers believe the presence of cover crops in the soil likely increased soil fertility for crop growth.
Biosolarization with cover crops helped lower weed growth compared to untreated soils. Reducing weeds can help crops compete more effectively for water and nutrients, which may improve yields and reduce the need for additional weed control.
Study recommendations
Based on the findings, using cover crops together with biosolarization shows promise for improving eggplant growth and reducing weeds. Farmers interested in sustainable practices may consider incorporating cover crops as an on-farm source of organic matter for biosolarization before planting their cash crops.
While the results are encouraging, the researchers recommend that these practices first be tested in small-scale trials on a farm to see how they perform under local conditions before expanding to larger fields.
Overall, combining cover crops with biosolarization may be a useful tool for growing healthier crops while controlling soil pests to support sustainable agriculture. Additionally, by managing pests without chemical fumigants, these practices have the potential to improve human health within agricultural systems.