Impacts of compost amendment type and application frequency on a fire-impacted grassland ecosystem

Composting organic matter can lower the global warming potential of food and agricultural waste and provide a nutrient-rich soil amendment. Compost applications generally increase net primary production (NPP) and soil water holding capacity and may stimulate soil carbon (C) sequestration. Questions remain regarding the effects of compost nitrogen (N) concentrations and application rates on soil C and greenhouse gas dynamics. In this study, we explored the effects of compost with different initial N quality (food waste versus green waste compost) on soil greenhouse gas fluxes, aboveground biomass, and soil C and N pools in a fire-impacted annual grassland ecosystem. Composts were applied annually once, twice, or three times prior to the onset of the winter rainy season. A low intensity fire event after the first growing season also allowed us to explore how compost-amended grasslands respond to burning events, which are expected to increase with climate change. After four growing seasons..., Methods
Field site
The site was located at the University of California Sierra Foothill Research and Extension Center (SFREC) in Browns Valley, California. Soils are derived from Mesozoic and Franciscan volcanic rock and classified as xeric Inceptisols and Alfisols in the Auburn-Sobrante complex (Soil Survey Staff 2020). The site had been grazed by cattle for at least 150 years (D. Flavell, personal communication). Average annual precipitation was 700 mm with pastures producing on average 3,300 kg ha-1 y-1 of biomass dominantly used for livestock forage. The study region has a Mediterranean climate where the growing season typically occurs from October to April or May and is characterized by cool, wet winters and warm dry summers.  The site was dominated by naturalized stands of annual grasses and forbs (Bartolome et al. 2007, Eviner 2016). The field sites were not seeded, irrigated, fertilized, or tilled. Naturalized annual plant species reseed and replace stands every year. This ecosy..., , # Impacts of compost amendment type and application frequency on a fire-impacted grassland ecosystem

[https://doi.org/10.5061/dryad.hhmgqnkr0](https://doi.org/10.5061/dryad.hhmgqnkr0)

## Description of the data and file structure

**Abbreviations for treatments:**

Treatments included unburned control (UCN), burned control (CN), and burned green waste (GW) or food waste (FW) applied once (one-time), two different years (two-time), or three different years (three-time)

TreatmentCN: Burned control, UCN: Unburned Control, GW: one-time green waste compost, GW2: two-time green waste compost, GW3 = three-time green waste compost, FW = one-time food waste compost, FW2 = two-time food waste compost.

Sampling years: Year 1 = 2019, Year 2 = 2020, Year 3 = 2021, Year 4 = 2022 or by year: 2018 (pre-treatment application), 2019, 2020, 2021, or 2022

Block: Block replicate of each treatment (B1, B2, or B3)

Plot: Plot replicated of each treatment within each block (P1-P6) 

Depth: Soil sampled d...