Nematodes and the micro-food web respond to plant litter type and placement when added to organic soil

Citation

Mosdossy, K., J. Whalen, B. Mimee, and C. Kallenbach. 2022. Nematodes and the micro-food web respond to plant litter type and placement when added to organic soil. Soil Ecology Society meeting 2022

Résumé en langage clair

Organic soils are ideal for growing vegetable crops, but are threatened by erosion and soil subsidence. Adding ligneous plant litter is expected to mitigate these losses. In this study, we assessed the change in nematode and microbial communities in a cultivated organic soil after applying ligneous plant litter to the soil. We found that both litter type (larch, ash, willow or miscanthus) and placement (incorporated with soil vs. on top) had an impact on microbial communities and soil nitrogen content.

Résumé

Organic soils are ideal for growing vegetable crops, but are threatened by erosion and soil subsidence. Adding ligneous plant litter is expected to mitigate these losses. However, their relatively high amounts of carbon (C) and low nitrogen (N) could affect microbial populations and C and N cycling.
Our objective was to assess the change in nematode and microbial communities in a cultivated organic soil after applying ligneous plant litter to the soil. We hypothesized that nematode Fungivore:Bacterivore positively correlates with lignin:N of the added litter because of increased fungal prey density. We also hypothesized that incorporating litter into the soil enriches nematodes because litter nutrients are more available for microbial growth. We tested the hypotheses in a greenhouse experiment with five litter treatments × two placements and used lettuce as a model crop. We tested four litters: tamarack (lignin:N = 338.9), white ash (lignin:N =131.7), willow (lignin:N = 64.7), and miscanthus grass (lignin:N=126.1). We deduced the structure of bacteria, fungi and nematode communities from a metabarcoding analysis that targeted the 16S/ITS/18S rRNA genes.
Incorporated larch significantly decreased nematode diversity (ANOVA, p<0.001). Litter placement and type explained ~20% of the variation of nematode diversity and composition (PERMANOVA, p < 0.001). Both fungi and bacteria communities significantly differed between plant litter types and placement (ANOVA, p<0.001). Soil nitrate was significantly higher when litter was incorporated (p<0.001). Lettuce biomass did not differ. Further analyses are underway to understand the patterns of C and N flux in relation to the micro-food web.

Date de publication

2022-05-17

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