Building houses and managing lawns could limit yard soil carbon for centuries

Abstract

Background: Comparisons of soil carbon (C) pools across land uses can be confounded by site-specific history. To better quantify the response of soil C pools to residential development and use, we compared yard soils (n = 20) to adjacent mown fields and second-growth forests within land-use clusters (LUC; n = 12). Land uses within clusters shared site-specific legacies (land use and other soil forming history) prior to residential development (15-227 years ago). We analyzed soil cores to 60-cm depth for carbon, nitrogen, and bulk density. Within one LUC, we monitored soil dissolved organic carbon, moisture, and thermal regimes to explain soil C dynamics. Results: We accounted for pre-development legacies to test how present uses affect soil properties. We found that yard soil C pools to 60-cm depth (9.07 ± 0.32 kg C m −2 ; mean ± SE) were smaller than fields (10.26 ± 0.44 kg C m −2) and forests (10.62 ± 0.87 kg C m −2). Fields contained more nitrogen to 60-cm depth (0.78 ± 0.043 kg N m −2) than yards (0.68 ± 0.030 kg N m −2) and forests (0.69 ± 0.057 kg N m −2). Time since development predicted decreased yard and field soil C/N, field soil N accumulation, and reduced yard bulk density. In old yards (> 150 years), where residents in recent times mowed monthly to bimonthly and left clippings on the lawn, there was evidence of soil C and N gains relative to old commercially managed yards mown weekly with clippings exported. Conclusions: Our study suggests land conversion to yard can limit soil C pools for centuries, with contemporary management key to that trajectory. Our research points to the importance of accounting for pre-development legacies to reveal the response of soil properties to land conversion and present use. This work can inform policies and land use intended to enhance the soil C sink and minimize development-related soil C losses.

Ditching Nutrients: Roadside Drainage Networks are Hotspots for Microbial Nitrogen Removal

“…Drying and rewetting has been shown to negatively impact DNRA compared denitrification, likely due to DNRA bacteria being more sensitive to fluctuating O 2 levels (Rahman et al., 2019). Additionally, soil mixing/compaction and mowing can cause a long‐term drop in soil C stocks (Peach et al., 2019), which may further limit DNRA (e.g., Hardison et al., 2015). In this case, ditch vegetation management practices such as mowing may favor N removal over retention.…”

Extreme Runoff of Chemical Species of Nitrogen and Phosphorus Threatens a Florida Barrier Island Lagoon

“…The South Prong drainage basin includes more open land, saw palmetto fields, mature citrus groves, and limited residential-commercial property relative to much more turfgrass and impervious surfaces in Crane Creek. Previous studies have found a lower reservoir of organic matter in residential lawns because thin (<20 cm) layers of turfgrass often cover soil amended by importing C-and N-poor, sand (Peach et al, 2019). This turfgrass scenario was common in our study area.…”