Proceedings - Soil Science Society of America最新文献

Information is needed on greenhouse gas (GHG) emissions due to tillage and crop type on sugarbeet (Beta vulgaris L.)-based crop rotations. We measured CO₂, N₂O, and CH₄ emissions as affected by tillage (conventional till [CT], no-till [NT], and strip till [ST]) under sugarbeet and spring wheat (Triticum aestivum L.) phases of an irrigated sugarbeet–pea (Pisum sativum L.)–spring wheat rotation from 2018 to 2021 in the US northern Great Plains. Greenhouse gases were measured using a static chamber at 3- to 28-day intervals, depending on plant growth and environmental conditions, throughout the year. The CO₂ and N₂O fluxes peaked for 2–8 months immediately after tillage, planting, fertilization, intense precipitation, and irrigation. The CH₄ flux varied little, except for some peaks in the first year. Cumulative annual CO₂ flux was 19%–30% greater for CT than NT in 2019–2020 and 2020–2021, and 13% greater for CT than ST in 2020–2021. Cumulative N₂O flux was 31%–36% greater for CT than ST in 2018–2019 and 2020–2021, but 33%–83% lower for sugarbeet than spring wheat in all years. Cumulative CH₄ flux was 83% lower for CT than NT and 68% lower for sugarbeet than spring wheat in 2018–2019. The GHG balance was 15%–23% greater for CT than NT and ST in 2019–2020 and 2020–2021 and 31% greater under sugarbeet than spring wheat in 2018–2019. No-tillage can reduce GHG emissions compared to conventional tillage, and sugarbeet can reduce N₂O emissions compared to spring wheat in sugarbeet-based crop rotations.

Soil quality index (SQI) helps quantify management practices impacts on the soil, providing information for producers in decision-making. Through evaluation in sugarcane areas, soil indicators were used to develop SQI to access and quantify the impacts of long-term vinasse application on the soil. The treatments consisted of two soil types: clayey (490 g kg⁻¹ clay) and sandy (80 g kg⁻¹ clay) and two conditions: with (70 m³ ha⁻¹ year⁻¹) and without vinasse application for 10 years. Soil samples were collected in the 0- to 10-cm, 10- to 20-cm, and 20- to 30-cm layers in each treatment. Four soil functions were developed to calculate SQI: root environment quality (REQ), air/water ratio (AWR), soil chemical quality (SCQ), and soil tolerance to erosion (STE). Twelve soil indicators related to soil fertility and aggregation/structure were used. The long-term vinasse application increased water storage (32%–58% of soil porosity), sum of bases (11–19 mmol_c dm⁻³) and aggregate stability index (41% vs. 78%) compared to without vinasse treatment in sandy soil. In the clayey soil, vinasse increased (p < 0.05) the REQ, SCQ, and STE functions by 10%, 14%, and 13%, respectively, besides not affecting AWR. The long-term application of vinasse promoted greater benefits, proportionally, in the sandy soil, with increments (p < 0.05) of 30% in AWR, 25% in SCQ, and 27% in STE. According to the SQI, long-term vinasse application increased the capacity of the clay soil to perform its functions by 8%, while it increased to the sandy soil was 22%.

Flooded rice (Oryza sativa L.) systems are critical for global food security but contribute significantly to anthropogenic greenhouse gas (GHG) emissions due to high methane (CH₄) emissions from anaerobic soils. Drill-seeding (DS) rice, which in California includes early-season irrigation flushes to establish the rice, has been shown to reduce CH₄ emissions compared to water-seeded (WS) systems. The effect of these early-season flushes on nitrogen (N) fertilizer losses and nitrous oxide (N₂O) emissions, however, is not well understood. In a 2-year study, we quantitatively compared DS to WS systems with respect to their global warming potential (GWP) (CH₄ + N₂O in CO₂ eq.), nitrate (NO₃⁻) accumulation during flushes, and crop N-uptake. Despite 0.68 kg ha⁻¹ more N₂O–N emissions in the DS system, GWP was 3700 CO₂ eq. kg ha⁻¹, a 42% reduction compared to 6340 CO₂ eq. kg ha⁻¹ in the WS system. This was due to a 46% reduction in CH₄ in the DS (94.5 CH₄–C kg ha⁻¹) relative to the WS (175.7 CH₄–C kg ha⁻¹) system. Nitrate accumulation in the DS system amounted to 26.2 kg NO₃–N ha⁻¹, and subsequent N losses via denitrification likely contributed to the 22.4 kg N ha⁻¹ less crop N-uptake in the DS system. These results suggest that DS rice has potential for improved environmental impact via GWP reductions but will require increased N inputs. Future efforts should focus on reducing N losses, which have a negative economic impact for the farmer and contribute to N₂O emissions.

Establishing connections between soil health indicators and crop performance will help ensure that tests recommended to farmers relate to outcomes of interest. This study assessed the relationship of soybean [Glycine max (L.) Merr] yield with three common soil health indicators: soil organic matter (SOM), permanganate oxidizable carbon (POXC), and autoclaved citrate extractable nitrogen (ACE-N). These tests were assessed alongside other factors (soil test phosphorus, soil test potassium [STK], mapped clay, planting date, summer precipitation, and location). Soil samples were collected from 457 producer-managed fields between 2019 and 2021 in Arkansas, Michigan, North Carolina, and Wisconsin. Planting date and yield were reported by producers, while mapped clay and rainfall were determined using publicly available data. Simple linear regression was used to assess the relationship between soil health indicators and yield: the natural log of SOM and POXC were positively associated with soybean yield (R² = 0.07, p < 0.001; R² = 0.03, p < 0.001), while ACE-N was not (p = 0.872). Multiple linear regression was used to further test the relationship of SOM and POXC with yield, while accounting for other factors that contribute to soybean yield. Models explained 27% of variation in yield, with significant factors including SOM or POXC, soybean planting date, STK, and mapped clay. Based on standardized coefficients, planting date was the most influential factor associated with yield. Broadly, our results indicate that improvements in yield are linked to higher SOM, but management decisions like planting early are critical for achieving high yields.

Poultry litter (PL) can be used as a viable alternative to phosphate fertilizers. However, there is a lack of information about phosphorus (P) distribution in inorganic (P_i) and organic (P_o) forms and its transformation in soils amended with PL of varying age (based on litter clean-out frequency) and application rate. This study aimed to determine the effect of PL age and application rate on soil P forms and their bioavailability. Soils were amended with 5 and 10 Mg ha⁻¹ PL using 6-, 18-, and 30-month-old litter and incubated for 6 months. Soil P fractionation was performed following the Hedley protocol. Soil P availability and soil P storage capacity (SPSC) were determined using Mehlich 3 (M3) extraction. Results indicated that P transformation from labile to stable P forms occurred over 150-day incubation. Litter age had no significant effect on the distribution of soil P forms. However, the highly reactive P_i (HRP_i) form was higher for treatments with 10 Mg ha⁻¹ PL on Day 0, indicating a risk for P loss, which was also revealed by negative SPSC for those treatments. At Day 0, M3-P was positively correlated to HRP_i. However, from Day 30 to 150, M3-P was strongly correlated to both HRP_i and moderately reactive P_i (MRP_i) forms, indicating MRP_i contribution to soil P availability. The negative relationship between HRP_i and SPSC further confirms that high HRP_i on Day 0 may be an environmental concern.

Soil compaction is a serious threat to soil functions and ecosystem services. Persistent soil deformation takes place when mechanical stress exceeds soil strength. Risk assessment models typically assume soil to be elastic to a precompression stress level and plastic above this threshold. Currently used procedures for estimating soil precompression stress imply applied stress in a logarithmic form that has been criticized. We performed uniaxial, confined compression tests on 117 soil samples with a well-defined stress history. Strain and stress were recorded at 200 levels of stress in the range of 0–1 MPa. Soil compressibility was calculated as incremental strain per incremental stress, using stress in arithmetic scale. For a given sample, a local minimum in compressibility appeared close to the preload applied to the sample prior to the compression test. This yield stress is suggested as an expression of soil precompression stress. Not all samples displayed a yield stress. Primarily soil exposed to a high preload did not exhibit a clear stress level with change in compressibility. This indicates that a physically based stress level pointing out a transition to plastic conditions will not exist for all soils. Our observation calls for new concepts in risk assessment. Tests with interpolation between a limited number of data points indicate that the yield stress—if existing—may be detected from classical compression data.

There are many fertilizer additives and alternatives that aim to increase plant nutrient use efficiency and reduce nutrient losses to the environment, here referred to collectively as enhanced efficiency fertilizers (EEFs). However, there is often insufficient published scientific field trial results across a variety of locations, climates, soils, cropping systems, and management scenarios to prove their efficacy and conditions for use. Guidelines for common minimum datasets and data stewardship in evaluating the agronomic performance and environmental impact of EEFs are needed for researchers to follow. Such guidelines will improve hypothesis testing centered on product efficacy and provide producers with guidance on how these technologies function and perform when integrated with other management practices within the 4R Nutrient Stewardship Framework. A scientific committee was formed to develop a set of protocol guidelines for evaluating EEFs in replicated, plot-based field trials on an international scale. The guidelines are composed of experimental design and core metadata, crop and soil analyses, environmental loss measurements, and data stewardship, and include both recommended and required components to allow for flexibility and adaptability depending on the trial location, objectives, infrastructure capacity, product type, and depth of understanding of the potential EEF efficacy. This approach will ensure consistency and compatibility in experimental design and data collection to support data integration, analysis, and reuse leading to large-scale impact and end-user confidence.

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.