"Soil Physiochemical Properties and Carbon Sequestration of Urban Landscapes in Lubbock, TX, USA"

Abstract Soil organic matter (SOM) accumulation and carbon (C) sequestration are ecosystem services (ESs) provided by urban landscapes that are dominated by continuous grass cover, such as residential lawns. Organic matter and C sequestration are expected to increase over time, but few studies have determined potential soil organic carbon (SOC) accumulation from residential lawns in semiarid climates. The objectives were to evaluate physiochemical attributes of urban soils established under turfgrass landscapes of different ages and determine soil factors that differentiate urban soils in semiarid climate of Lubbock, TX. Soil samples (0-10 cm) were obtained from 10 residential lawns of homes built: pre-1970 (oldest), 1971-1990 (middle), 1991-2010 (newer), and after 2011 (newest). Soil texture, bulk density, extractable nutrients [phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe)], pH, SOM, SOC, and total nitrogen (TN) were determined. Bulk density and pH were highest in newest homes and lowest in oldest homes. Increasing years of lawn establishment increased SOM, SOC, and TN content. Linear regression determined 0.036% annual increase in SOM for residential lawns, but SOC accumulated at 0.021 kg C m-2 yr-1 for 53.6 yr. In principal component (PC) analysis, SOM, SOC, and TN contributed most to PC1 (36.2%) reflecting components separating residential lawns by years of establishment, and primarily soil texture components for PC2 (22.5%). The results of this study show that home age is a strong determinant of soil carbon content in semiarid urban turfgrass systems, with the greatest accumulation threshold in oldest homes over 50 years of age.