Presenter: Maya Treder – General Science
Faculty Mentor(s): Ashley Shaw, Lauren Hallett
Session: (In-Person) Oral Panel—Fuel, Fire, Grass and Compost, Poster Presentation
California rangelands are often over-grazed, nutrient-depleted, and subject to variable rainfall. Compost amendments are gaining popularity as a management tool due to their potential for soil carbon sequestration. Despite positive effects on plant growth, little is known about how soil communities respond to these amendments, especially across variable precipitation conditions. Nematodes are excellent indicators of soil community responses as they span every trophic level and are sensitive to changing environments. Here, we examined how amendment treatments (compost, fertilizer, none) affect nematode communities across variable precipitation conditions (drought, irrigation, wet). We hypothesized: 1) amendments increase nematode abundance, where compost has a greater positive effect than fertilizer; 2) nematodes respond positively to elevated soil moisture and negatively to drought; 3) effects of amendment and precipitation are interactive, where compost mitigates drought’s effects on nematodes. As expected, compost increased nematode abundance relative to other amendment treatments. However, overall, nematodes were most abundant under ambient precipitation, contrary to expectations. This was due to the precipitation-amendment interaction. While compost and fertilizer had similar positive effects on nematodes under ambient and irrigation, under drought, fertilizer had a negative while compost had a positive effect on nematode abundance compared to the no amendment treatment.