Philip Waisen, PhD (he/him/his)
Vegetable Crops Advisor
University of California Cooperative Extension
Palm Desert, CA, USA
Oli Bachie
Imperial County Director
University of California Cooperative Extension
Holtville, California, United States
Aliasghar Montazar
Irrigation and Water Management Advisor
University of California Cooperative Extension
Holtville, California, United States
Cuong Nguyen
Food Safety and Organic Production Advisor
University of California Cooperative Extension
Holville, California, United States
Esther Lofton
Urban Watershed Resilience Advisor
University of California Cooperative Extension
Irvine, California, United States
Ana Resendiz
Community Education Specialist
University of California Cooperative Extension
Holtville, California, United States
High temperatures during summer fallow in Low Desert vegetable production systems deteriorate soil organic matter to negligible levels, compromising microbial activity and warranting the need to utilize soil conservation practices. This study examined the benefits of using sunn hemp (SH; Crotalaria juncea), cowpea (CP; Vigna unguiculata), and sudangrass (SG; Sorghum bicolor x S. bicolor var. sudanese) as cover crops compared to fallow in summer of 2024 in Coachella, CA. Each cover crop was sown at 99 t seeds/ha, terminated by mowing and rototilling after 7 weeks, and followed by okra planting. Before termination, 6 soil cores were collected from cover crop rhizospheres for microbial and nutrient analyses. Soil environmental DNA was extracted and PCR amplified using universal primers targeting bacteria (16S rDNA) and fungi (ITS). Amplicons were sequenced using MiSeq and subjected to bioinformatics pipeline. At least 188 species of bacteria and fungi were detected, spanning 146 genera, 101 families, and 23 phyla. At least 93% of the species were non-pathogenic and performed various ecosystem functions while only 7% were identified as pathogenic. SH and CP increased fungal abundance and diversity while CP and SG increased bacterial diversity. However, bacteria and nematode abundance were not affected. Okra yield was positively correlated with fungal abundance and diversity as well as soil nitrogen and potassium levels. SH and CP improved okra yield attributing to microbial activity and nutrient cycling. Thus, cover crop can be a viable option for okra production in the desert.