Proceedings - Soil Science Society of America最新文献

Detailed soil property maps are increasingly important for land management decisions and environmental modeling. The US Soil Survey is investing in production of the Soil Landscapes of the United States (SOLUS), a new set of national predictive soil property maps. This paper documents initial 100-m resolution maps of 20 soil properties that include various textural fractions, physical parameters, chemical parameters, carbon, and depth to restrictions. Many of these properties have not been previously mapped at this resolution. A hybrid training strategy helped increase training data by roughly 10-fold over previous similar studies by combining commonly used laboratory data with underutilized field descriptions tied to soil survey map unit component property estimates (to help represent within polygon variability) as well as randomly selected soil survey map unit weighted average property estimates. Relative prediction intervals were used to help select which training data sources improved model performance. Conventional and spatial cross-validation strategies yielded generally strong coefficients of determination between 0.5 and 0.7, but with substantial variability and outliers among the various properties, types of training data, and depths. Internal review of the maps highlighted both strengths and weaknesses of the maps, but most of the critical comments were in areas with high model uncertainty that can be used to guide future improvements. Generally, previously glaciated areas and complex large alluvial basins were harder to model. The new SOLUS 100-m maps will be updated in the future to address identified issues and feedback as users interact with the data.

The variation in the soil microbial community composition over time was assessed at monthly time steps for 1 year in three neighboring Mollisols spanning a drainage gradient. This was done to distinguish between natural oscillations in the community composition versus lasting adaptations to environmental factors such as soil water availability. To isolate soil water availability as a controlling factor, we selected three soils sharing the same soil order (fine-silty, superactive Argixerolls/Argialbolls); slope (0%–1%); temperature regime (mesic); moisture regime (xeric); and land use history (continuous grassland for the past 10 years) but differing in drainage class (well-drained vs. moderately well-drained vs. poorly drained). Changes in microbial diversity were quantified by monitoring the bacterial community at monthly intervals for 1 year. Within individual soils, α-diversity varied little with season and drainage classes. Despite the three soils experiencing the same climate regime and vegetation/land use, they exhibited distinct community composition and turnover, which we attribute to differences in moisture availability across drainage and seasons. We posit that a seasonal recurring drop in soil redox potential induced by seasonal water saturation in the poorly drained soil is the most probable cause setting the microbial community of that soil apart from those in the better drained soils. Our investigation suggests that not all indicators of microbial diversity share the same sensitivity to seasonal and drainage-related soil moisture variations.

Understanding the effects of abandoned coal mine ecological restoration on soil quality and function is important to protect the regional ecological environment. This study aims to evaluate the ecological restoration effects of soil quality in abandoned coal mine area. Taking Fengcheng County, a typical coal-rich area in southern China, as a case, this study took 120 soil samples to investigate the influence of restoration years on soil quality by using an integrated soil quality index (SQI). Results indicated that restoration years had significant effects on the saturated hydraulic conductivity (Ks) by affecting the soil bulk density, clay content, and soil water content. Furthermore, clay, soil organic matter, Ks, and pH were selected to assess the effect of ecological restoration years on soil quality. It was found that the ecological restoration 8 years (ER8) site had higher SQI value, indicating ecological restoration years showed a positive correlation with SQI in abandoned coal mine area. Since there was a 4-year gap between ecological restoration 4 years site and ER8 site, the ecological restoration may be effective between 5 and 8 years. The results of this study are of great significance for improving the effects of ecological restoration and management in abandoned coal mine area.

Information on water absorption from the air by urea fertilizers and on NH₃ loss when applied to grasslands is limited. Urea application to grassland is typically broadcast (Bcast), whereas urea-ammonium nitrate (UAN) is applied either Bcast or in bands (dribble). This work was conducted to (1) evaluate water absorption from the air by Bcast granular urea, Bcast UAN, and dribble UAN under laboratory conditions, and (2) compare NH₃ losses from Bcast urea, Bcast UAN, and dribble UAN when applied to a grassland. Six field studies were conducted from 2017 to 2019. In the laboratory, Bcast UAN exposed to 100% relative humidity absorbed water from air at a faster rate than dribble UAN and Bcast urea. In the field, all three fertilizers lost similar amounts of NH₃ when applied to relatively wet soil (> −0.1 MPa). In contrast, when the fertilizers were applied to dry soil (≤ −1.2 MPa), Bcast UAN lost the most NH₃ (17.3% and 19.8%) likely because of its capacity to absorb water from the air. Also, at −1.2 MPa, dribble UAN lost more NH₃ than Bcast urea (15.3 vs. 10.7%, p < 0.05), probably because the low osmotic potential of UAN (−55 MPa) allowed it to absorb water from the soil at a faster rate than urea could absorb water from the air. In contrast, when the soil water potential was −5.7 MPa, dribble UAN lost less NH₃ than Bcast urea (4.4 vs. 17.3%, p < 0.05), likely because the low soil water potential reduced its water absorption.

This study investigates the utility of plant δ¹³C natural labeling in predicting the impacts of environmental shifts on carbon cycling within ecosystems, particularly focusing on paddy fields treated with maize (Zea mays L.) residues and biochar. Specifically, it examines how soil δ¹³C and the sources of soil organic carbon (SOC), respond in paddy fields (which cultivate C₃ plants like rice) when amended with maize residues, maize biochar, and silica-enriched biochar (derived from C₄ plants). Conducted in the Fuzhou paddy fields, the experiment included control groups and treatment groups with maize residue (4 t ha⁻¹), maize biochar (4 t ha⁻¹), and silicon-modified maize biochar (4 t ha⁻¹) during both the early and late rice growth periods. The results indicate that all soil treatments increased soil δ¹³C. The application of maize residues notably affected the δ¹³C of the upper soil profile (0–15 cm) differently from the deeper layers (15–30 cm), and it increased soil organic C more than biochar or silicon-modified maize biochar. Soil available P (AP) and pH emerged as significant factors linking δ¹³C, influencing rice yield through changes in soil physicochemical properties. Unlike maize residues, which reduced rice yields, applications of biochar and silicon-modified maize biochar increased rice yields. The latter, which was particularly effective in lowering SOC decomposition rates and addressing rice's silica needs, emerged as the preferred option. The study highlights maize biochar and silicon-modified maize biochar as sustainable alternatives to maize residues for rice cultivation, enhancing soil fertility, carbon pool stability, and yields.

Researchers in urban environments sample where people live and work. However, there is limited extant guidance available to scientists engaging with community stakeholders to sample soils in urban settings. Leveraging our cumulative experiences, insights gained from community collaborations, and interdisciplinary literature, we present a community-engaged framework for urban soils research. Community-engaged research frameworks emerged over the past two decades to foster trust and respect between communities and researchers as a response to historical exploitation of communities by the academy. Today, these frameworks have become standard for social and public health researchers investigating the physical well-being of communities. However, there is no equivalent framework for scientists studying the soils that underpin the physical and ecological well-being of the same communities. Here, we present the first such framework for soil scientists that incorporates nuanced aspects that are often overlooked. Our proposed framework recognizes the iterative nature of collaboration with community stakeholders and highlights the significance of ethical considerations throughout the research process by emphasizing protection of community stakeholders from harm, involvement of all parties in decision-making processes, maintaining informed consent, and fostering mutual accountability among researchers throughout the research and sampling process.

The TEROS 10 and TEROS 12 are widely used capacitance-based sensors for measuring volumetric water content ($�{\theta }_v$), but few systematic studies of the measurement volume and accuracy of these sensors have been published. The objectives of this study were to (1) calibrate and validate these sensors in mineral soils, (2) determine the sensing volume of each sensor, and (3) evaluate the temperature sensitivity of the sensors. Both sensors were calibrated in the laboratory using columns of packed soil at multiple moisture levels from air-dry to near saturation. Sensors were validated using additional laboratory and field measurements. The sensing volume was determined by quantifying the response of raw sensor outputs while increasing the level of oven-dry sand, moist sand (0.100 cm³ cm⁻³), or water around the sensor in the radial and axial directions. Temperature sensitivity was tested in controlled conditions over a range of temperatures from 2°C to 40°C using encapsulated sensors in packed soil columns at constant $�{\theta }_v$. Linear calibration models resulted in mean absolute error ≤0.030 cm³ cm⁻³ for both sensors during laboratory and field validations. In moist sand, the sensing volume contributing 95% of the maximum sensor response was 439 cm³ for the TEROS 10 and 423 cm³ for the TEROS 12. Both sensors exhibited changes in $�{\theta }_v$ of ≤0.02 cm³ cm⁻³ when subjected to a temperature change from 2°C to 40°C. For the soils considered here, both sensors demonstrated accuracy that is likely sufficient for a variety of agricultural and hydrological applications.

Increased environmental nitrogen (N) losses have prompted the use of enhanced efficiency nitrogen fertilizers, including nitrification inhibitors. However, the comparative effects of nitrification inhibitors with conventional nitrogen fertilizers and herbicides on soil nitrification and nitrogen losses remain poorly understood. This study evaluated the impact of a nitrification inhibitor (Instinct NXTGEN), two nitrogen sources (broadcast urea vs. injected aqueous ammonia), and a preemergence herbicide (Acuron) on (1) soil nitrification through a 25-day soil incubation experiment and (2) NH₃ volatilization, NO₃-N leaching, and N₂O-N emissions through a 31-day soil column study in loamy sand soil. In both experiments, treatments included combinations of nitrification inhibitor versus no inhibitor, two nitrogen sources, and preemergence herbicide versus no herbicide. Results revealed that nitrogen source significantly influenced nitrification, with injected aqueous ammonia reducing nitrification by 33% compared to surface broadcast urea. Nitrification inhibitors and herbicide had no effect on soil nitrification. Injected aqueous ammonia reduced NH₃ volatilization by 87% compared to surface broadcast urea, but the effect of the nitrification inhibitor on NH₃ volatilization was inconsistent across both nitrogen sources. Injected aqueous ammonia led to 39% higher cumulative nitrogen (NO₃-N + NH₄-N) leaching than urea, while the nitrification inhibitor had an inconsistent effect on NO₃-N leaching across both nitrogen sources. No significant differences in N₂O-N emissions were observed among treatments, and the herbicide had no effect on any measured parameters. These findings suggest that nitrogen source plays a more critical role in regulating soil nitrogen losses than nitrification inhibitors or herbicides.

Plant-available soil-water and adequate soil aeration within the root zone are essential corequisites for successful plant growth. Characterization of these two requirements for plant growth is generally done by independent measurements of water and air phase properties and functions in soil, with limited emphasis on their combined effect. This study investigated soil-water characteristic (SWC) measurements in vadose soil profiles (up to 117-cm depth) in six pasture soils to examine the combined behavior of soil-water and diffusion-controlled aeration within the root zone. The soil moisture measurements were made over matric potentials ranging from −1 to −1500 kPa using tension table and pressure plate apparatus. The van Genuchten model was used to parameterize the measured SWC curve, while the Millington–Quick model was used to derive soil-gas diffusivity from measured soil physical properties. Based on two simple indices, derived to represent plant-available soil-water and soil aeration status at a given moisture content, we propose an assessment matrix, which illustrates how a soil satisfies the corequisites for successful plant growth, as it drains to different matric potentials upon irrigation. Results show a pronounced effect of soil texture and, to a lesser extent, soil structure on satisfying these corequisites. With the aid of the assessment matrix, we observed that loam, sandy loam textures exhibited a good overall performance, while sand, clay loam, and clay soils struggled to meet these corequisites during drainage.

Efficient and harmless treatment of microplastics in soil is the current focus of microplastic pollution management. In this study, the pyrolysis effect of soil microplastics at different temperatures and holding times was analyzed. The results showed that temperature and holding time significantly affected the morphology and compositional structure of soil. Pure microplastics and product adhesion after pyrolysis at low temperature (400°C) were not easy to remove. Interestingly, compared with pure polyethylene (PE), direct pyrolysis of microplastics in soil could obtain better results, and the content of organic matter and polycyclic aromatic hydrocarbons (PAH) could be significantly reduced. However, the pyrolysis performance was very unsatisfactory even if the action time was prolonged at 400°C. Prolonged high-temperature treatment accelerated the fragmentation of the alkane main chain of PE, thus generating more PAH, and the temperature was not high enough (400°C) for further effective degradation of PAH into carbon dioxide and water. Therefore, higher temperature and longer holding time need to be selected to ensure the pyrolysis performance. This study revealed the role and mechanism of pyrolysis in soil microplastic mixed systems, aiming to provide a basis for the treatment of microplastics in terrestrial ecosystems.