Effects of climate and soil properties on U.S. home lawn soil organic carbon concentration and pool

Changes of soil carbon along precipitation gradients in three typical vegetation types in the Alxa desert region, China

The changes and influencing factors of soil inorganic carbon (SIC) and organic carbon (SOC) on precipitation gradients are crucial for predicting and evaluating carbon storage changes at the regional scale. However, people's understanding of the distribution characteristics of SOC and SIC reserves on regional precipitation gradients is insufficient, and the main environmental variables that affect SOC and SIC changes are also not well understood. Therefore, this study focuses on the Alxa region and selects five regions covered by three typical desert vegetation types, Zygophyllum xanthoxylon (ZX), Nitraria tangutorum (NT), and Reaumuria songarica (RS), along the climate transect where precipitation gradually increases. The study analyzes and discusses the variation characteristics of SOC and SIC under different vegetation and precipitation conditions. The results indicate that both SOC and SIC increase with the increase of precipitation, and the increase in SOC is greater with the increase of precipitation. The average SOC content in the 0-300cm profile is NT (4.13 g kg-1) > RS (3.61 g kg-1) > ZX (3.57 g kg-1); The average value of SIC content is: RS (5.78 g kg-1) > NT (5.11 g kg-1) > ZX (5.02 g kg-1). Overall, the multi-annual average precipitation (MAP) in the Alxa region is the most important environmental factor affecting SIC and SOC.

Carbon Sequestration in Turfgrass–Soil Systems

Plants are key components of the terrestrial ecosystem carbon cycle. Atmospheric CO₂ is assimilated through photosynthesis and stored in plant biomass and in the soil. The use of turfgrass is expanding due to the increasing human population and urbanization. In this review, we summarize recent carbon sequestration research in turfgrass and compare turfgrass systems to other plant systems. The soil organic carbon (SOC) stored in turfgrass systems is comparable to that in other natural and agricultural systems. Turfgrass systems are generally carbon-neutral or carbon sinks, with the exception of intensively managed areas, such as golf course greens and athletic fields. Turfgrass used in other areas, such as golf course fairways and roughs, parks, and home lawns, has the potential to contribute to carbon sequestration if proper management practices are implemented. High management inputs can increase the biomass productivity of turfgrass but do not guarantee higher SOC compared to low management inputs. Additionally, choosing the appropriate turfgrass species that are well adapted to the local climate and tolerant to stresses can maximize CO₂ assimilation and biomass productivity, although other factors, such as soil respiration, can considerably affect SOC. Future research is needed to document the complete carbon footprint, as well as to identify best management practices and appropriate turfgrass species to enhance carbon sequestration in turfgrass systems.

Estimation of soil organic carbon stocks of two cities, New York City and Paris

In cities, the strong heterogeneity of soils, added to the lack of standardized assessment methods, serves as a barrier to the estimation of their soil organic carbon content (SOC), soil organic carbon stocks (SOCS; kgC m^-2) and soil organic carbon citywide totals (SOCCT; kgC). Are urban soils, even the subsoils and sealed soils, contributing to the global stock of C? To address this question, the SOCS and SOCCT of two cities, New York City (NYC) and Paris, were compared. In NYC, soil samples were collected with a pedological standardized method to 1 m depth. The bulk density (D_b) was measured; SOC and SOCS were calculated for 0-30 cm and 30-100 cm depths in open (unsealed) soils and sealed soils. In Paris, the samples were collected for 0-30 cm depth in open soils and sealed soils by different sampling methods. If SOC was measured, D_b had to be estimated using pedotransfer functions (PTFs) refitted from the literature on NYC data; hence, SOCS was estimated. Globally, SOCS for open soils were not significantly different between both cities (11.3 ± 11.5 kgC m^-2 in NYC; 9.9 ± 3.9 kgC m^-2 in Paris). Nevertheless, SOCS was lower in sealed soils (2.9 ± 2.6 kgC m^-2 in NYC and 3.4 ± 1.2 kgC m^-2 in Paris). The SOCCT was similar between both cities for 0-30 cm (3.8 TgC in NYC and 3.5 TgC in Paris) and was also significant for the 30-100 cm layer in NYC (5.8 TgC). A comparison with estimated SOCCT in agricultural and forest soils demonstrated that the city's open soils represent important pools of organic carbon (respectively 110.4% and 44.5% more C in NYC and Paris than in agricultural soils, for 0-30 cm depth). That was mainly observable for the 1 m depth (146.6% more C in NYC than in agricultural soils). The methodology to assess urban SOCS was also discussed.

Sources of variation in home lawn soil nitrogen dynamics

Urban, suburban, and exurban lawns are an increasingly important ecosystem type in the United States. There is great concern about the environmental performance of lawns, especially nitrate (NO) leaching and nitrous oxide (NO) flux associated with nitrogen (N) fertilizer use. Previous studies of lawn N dynamics have produced conflicting results, with some studies showing high NO leaching and NO flux and others showing lower losses and high retention and cycling of N inputs. We hypothesized that this variation is caused by differences in lawn management and soil properties that control root and soil organic matter (SOM) dynamics that influence N cycling processes. We tested these hypotheses by making measurements of soil NO, root biomass, rates of potential net N mineralization and nitrification, NO flux, and SOM levels in samples from the front and backyards of residential homes in suburban and exurban neighborhoods with contrasting soil types in the Baltimore metropolitan area. There were no differences between front and backyards, between suburban and exurban neighborhoods, or between different soil types. Further, there were no significant relationships between root biomass, SOM, soil NO levels, and NO fluxes. These results suggest that lawns have uniformly high rates of plant productivity that underlies high levels of SOM and N retention in these ecosystems across the Baltimore metropolitan area.