Preliminary data on biodiversity effects of replacing plastic row covers with legume and non-leguminous covers in organic artichoke cropping

The purpose of this study was to investigate how replacing polyethylene row covers with other types of cover influences soil properties, microbial diversity, the composition of soil communities, and carbon metabolism in artichoke cropping. We carried out five treatments in four replicates, including plastic film, buckwheat, kurapia, crimson clover, and white clover. The samples were collected after rainfall events totalling 2 in. of precipitation during February 2024.

In the cross-sectional data, results were comparable between treatments with regards to physical and chemical properties, but there were significant differences in soil moisture and pH, with plastic having the lowest moisture and lowest pH. Higher CFUs in plastic at a 10^-4 dilution were noted.

For the composition and abundance of bacteria, the results indicated the following differences between white clover vs. plastic: higher Adhaeribacter sp. and Phycicoccus sp. abundance in white clover treatments; higher Rhodobacter sp. and Sphingobium sp. abundance in plastic treatments. The following differences were observed between the legume treatment vs. the control: Phycicoccus sp. and Stenotrophomonas sp. abundance was higher in the legume treatment. Results with low fold change values <1.33 were omitted.

The Chi-square test was negative for differences in proportions of carbon sources that could be metabolized in Biolog Ecoplate trials by each group (p=0.16). There was a gap in the mosaic plot between the proportion of carbon sources metabolized by white clover communities and other treatments. For the artichokes, the GLM logit model indicated a difference between white clover treatments when compared with other treatments (p=7.76*10^-5). The carbon sources that differed significantly in the microbes' ability to metabolize themwere delta-glucosaminic acid, L-alpha-glycerol phosphate, glucose-1-phosphate, i-erythritol, itaconic acid, phenylalanine, serine, and threonine.

Further studies should include microbial biomass analyses and nutrient analyses, and consider the effects of the treatments on yield. Longitudinal analysis of soil physical and chemical properties will confirm the effects of the treatments on physical and chemical properties of the soil.