Temporal Variation Of Soil Research Articles

Temporal variation of soil N supply defines N fixation in soybeans

Soybean [Glycine max (L.) Merr.] plays a critical role in global food security and sustainability, acquiring most of the nitrogen (N) required for growth and high-protein seeds from symbiotic N fixation (SNF). However, there is scarce information on how soil N supply interacts with N fixation (kg ha−1) throughout the growing season. This study aims to (1) evaluate the allometric relationships between the total N uptake and dry matter by N source (soil and fixation), (2) describe seasonal changes on soil-plant N dynamics among genotypes with contrasting genetic background (released between 1981 and 2019), and (3) assess the influence of soil NO3 and NH4 on the temporal SNF changes during the growing season. Four genotypes were field grown during 2019 and 2020. Bayesian non-linear models described seasonal change on dry matter, N uptake, soil NO3, and NH4 (60 cm depth). The allometric relationship between N uptake and dry matter indicated that total N status is more sensitive to variations in N uptake from the soil than from fixation. Seasonal exposure to NH4 (given by the area under the curve) and a delay on maximum NO3 availability from early to mid-season suppressed end-season N fixation by two-fold the benefit on soil N uptake (kg ha−1). Both the magnitude and timing of soil N sources affected N uptake in all tested genotypes. Future research must explore broader SNF levels for understanding to what extent soil N can affect the N uptake sources, especially SNF, without decreasing seed yield in soybeans.

Influencing Factors of the Spatial–Temporal Variation of Layered Soils and Sediments Moistures and Infiltration Characteristics under Irrigation in a Desert Oasis by Deterministic Spatial Interpolation Methods

Soil moisture is the main limiting factor for crop growth and the sustainable development of oases in arid desert areas. Therefore, the temporal and spatial variation and infiltration laws of oasis soil moisture should be studied. The objective of this study is to reveal the influencing factors of the spatial–temporal variation of layered soil and sediment moisture and infiltration characteristics under irrigation in desert oases. Hydraulic conductivities were measured using the double-ring infiltrometer, while the regional and site soil moistures were measured and calibrated using weighted method and neutron moisture meter. Deterministic spatial interpolation methods, including multiquadric radial basis function, inverse distance weighted, and local polynomial regression isogram, were adopted to map the regional distribution of hydraulic conductivities, spatial soil moistures, and spatial–temporal isogram of the point site soil moistures in Yaoba Oasis, respectively. Results showed that the leading influencing factors of the (1) regional spatial soil moisture were soil and sediment permeability, stream link direction, microclimate, and dewfalls; (2) spatial layered soil and sediment moistures were microclimate and dew condensation; and (3) spatial–temporal variation at the point site profiles were soil texture, water requirement, and preferential flow. Under irrigation, soil moisture increased significantly, in which the maximum increase was 10.8 times the original state, while the recharging depth substantially increased up to 580 cm with the preferential flow. The spatial–temporal variation of the soil moisture under irrigation indicated that the best irrigation frequency should be 15 days per time. Moreover, the infiltration process can be divided into the preferential flow, piston flow, and balanced infiltration stages.

Controls on Fine-Scale Spatial and Temporal Variability of Plant-Available Inorganic Nitrogen in a Polygonal Tundra Landscape

Nitrogen availability in the Arctic strongly influences plant productivity and distribution, and in permafrost systems with patterned ground, ecosystem carbon and nutrient cycling can vary substantially over short distances. Improved understanding of fine-scale spatial and temporal variation in soil N availability is needed to better predict tundra responses to a warming climate. We quantified plant-available inorganic nitrogen at multiple soil depths in 12 microhabitats associated with a gradient from low-center ice-wedge polygons to high-center polygons in coastal tundra at Utqiaġvik (formerly Barrow), Alaska. We measured vegetation composition, biomass, N content, and rooting depth distribution, as well as soil temperature, moisture, pH, and thaw depth to determine relationships between the spatial and temporal variability in N availability and environmental and vegetation drivers. Soil moisture varied across the microhabitats of the polygonal terrain and was the most important variable linked to distribution of both ammonium and nitrate, with ammonium predominating in wetter areas and nitrate predominating in drier areas. Total inorganic N availability increased as the soil in the active layer thawed, but the newly available N near the permafrost boundary late in the season was apparently not available to roots and did not contribute to plant N content. Nitrate in the drier sites also was not associated with plant N content, raising the possibility of N losses from this N-limited ecosystem. The strong relationship between soil moisture, inorganic N availability, and plant N content implies that understanding hydrological changes that may occur in a warming climate is key to determining nutrient cycling responses in complex polygonal tundra landscapes.

Soil Net Nitrogen Mineralization at Different Ecosystem Development Stages after the Year 2000 Eruption on Miyakejima Island

Soil nitrogen (N) mineralization is a central process in the N cycle in terrestrial ecosystems. Previously many studies were conducted on soil N mineralization in terrestrial ecosystems, but those studies remain unclear due to large spatial and temporal variations. In present study soil N mineralization rates were measured in situ by using a resin core technique. The study reports the relationship of these rates with environmental factors at ten sites with various vegetation and soil properties which formed after the latest eruption in year 2000 on a volcanic island, Miyakejima. Miyakejima has diverse ecosystems, from grasslands with little soil organic matter to mature forests. With little damage from the year 2000 eruption, it is suitable for exploration of spatial and temporal variations in soil N mineralization. Annual soil N mineralization rates ranged from 0.9 to 52.5 kg N ha-1 yr-1 and were higher in the presence of the N-fixing vegetation Alnus sieboldiana. Present study data along with other data obtained from insitu observation suggested that soil C/N ratio can be a good indicator of annual soil N mineralization rate, like many previous studies pointed out; however, the relationship between the rate and soil C/N ratio was complicated due to some factors, such as existence of N-fixing vegetation and high sulfur dioxide gas exposure.

Spatial and Temporal Variation of Soil and Water Salinity in the South‐Western and South‐Central Coastal Region of Bangladesh

AbstractSalinity intrusion is one of the major water‐related problems in the coastal region of Bangladesh. The intention of this study was to discuss the spatial distribution of soil and water salinity with their severity levels using geospatial techniques. The spatial analysis shows about 222 300 ha of new land being affected by various degrees of soil salinity during the last four decades. The analysis revealed that the spatial extent of salinity has been following an increasing trend and the movement of soil salinity has moved north from the coast. An increasing trend of salinity concentration in the rivers has already been found in the Lower Meghna River, Alaipur Khal (creek) of Daratona River, Gorai Madhumati, Rupsa Passur River and Bishkhali River in different districts of coastal Bangladesh. The groundwater is contaminated with a high level of salinity, which affects sources of drinking water, agriculture and the irrigation sector. Increased soil and water salinity levels cause an unfavourable environmental and hydrological situation that restricts usual crop production throughout the year. This research will assist decision makers and planners in taking proper initiatives for developing integrated land and water resources management plans for the coastal regions, which have similar environmental settings along the Bay of Bengal. Copyright © 2017 John Wiley & Sons, Ltd.

Contrasting grass nitrogen strategies reflect interspecific trade-offs between nitrogen acquisition and use in a semi-arid temperate grassland

Nitrogen (N) niche differentiations play an important role in community structure and biogeochemical cycling in terrestrial ecosystems. However, very few studies have examined how plant N strategies specialize via trade-offs between N acquisition and use abilities under natural field conditions. A field experiment was conducted to investigate N strategies by coexisting grass species using the in-situ stable isotope labeling technique. We injected 15N–labeled nitrate, 15N–labeled ammonium, and 13C-15N-labeled glycine solutions in early and late vegetative growing seasons. Shoot δ15N and N concentration were measured to determine the N uptake and use abilities of 4 common species. All plant species preferred to take up nitrate (the dominant N form) over ammonium and glycine, and N-acquisition capacity varied with temporal variation of soil N. However, the dominant species was more N-conservative than less-dominant species and had lower overall N uptake rates (shoot 15N excess 48 hours after injection) and higher N use efficiencies (aboveground biomass : N ratio). The different N strategies may reflect mixed effects of environmental filtering and interspecific competition and have significant implications for species coexistence as well as for ecosystem functions such as nutrient cycling.

Insensitivity of Soil Microbial Activity to Temporal Variation in Soil N in Subarctic Tundra: Evidence from Responses to Large Migratory Grazers

Large migratory grazers commonly influence soil processes in tundra ecosystems. However, the extent to which grazing effects are limited to intensive grazing periods associated with migration has not previously been investigated. We analyzed seasonal patterns in soil nitrogen (N), microbial respiration and extracellular enzyme activities (EEAs) in a lightly grazed tundra and a heavily grazed tundra that has been subjected to intensive grazing during reindeer (Rangifer tarandus L.) migration for the past 50 years. We hypothesized that due to the fertilizing effect of the reindeer, microbial respiration and EEAs related to microbial C acquisition should be higher in heavily grazed areas compared to lightly grazed areas and that the effects of grazing should be strongest during reindeer migration. Reindeer migration caused a dramatic peak in soil N availability, but in contrast to our predictions, the effect of grazing was more or less constant over the growing season and the seasonal patterns of microbial activities and microbial N were strikingly uniform between the lightly and heavily grazed areas. Microbial respiration and the EEAs of β-glucosidase, acid-phosphatase, and leucine-aminopeptidase were higher, whereas that of N-acetylglucosamidase was lower in the heavily grazed area. Experimental fertilization had no effect on EEAs related to C acquisition at either level of grazing intensity. Our findings suggest that soil microbial activities were independent of grazing-induced temporal variation in soil N availability. Instead, the effect of grazing on soil microbial activities appeared to be mediated by substrate availability for soil microorganisms. Following a shift in the dominant vegetation in response to grazing from dwarf shrubs to graminoids, the effect of grazing on soil processes is no longer sensitive to temporal grazing patterns; rather, grazers exert a consistent positive effect on the soil microbial potential for soil C decomposition.

Dynamic factor analysis of surface water management impacts on soil and bedrock water contents in Southern Florida Lowlands

Summary As part of the C111 spreader canal project, structural and operational modifications involving incremental raises in canal stage are planned along one of the major canals (i.e., C111) separating Everglades National Park and agricultural production areas to the east of the park. This study used Dynamic Factor Analysis (DFA) as an alternative tool to physically based models to explore the relationship between different hydrologic variables and the effect of proposed changes in surface water management on soil and bedrock water contents in south Florida. To achieve the goal, objectives were to: (1) use DFA to identify the most important factors affecting temporal variation in soil and bedrock water contents, (2) develop a simplified DFA based regression model for predicting soil and bedrock water contents as a function of canal stage and (3) assess the effect of the proposed incremental raises in canal stage on soil and bedrock water contents. DFA revealed that five common trends were the minimum required to describe unexplained variation in the 11 time series studied. Introducing canal stage, water table evaporation and net recharge resulted in lower Akaike information criterion (AIC) and higher Nash–Sutcliffe ( C eff ) values. Results indicated that canal stage significantly ( t > 2) drives temporal variation in soil and bedrock water contents, which was represented as scaled frequency while net surface recharge was significant in seven out of the 11 time series analyzed. The effect of water table evaporation was not significant at all sites. Results also indicated that the most important factor influencing temporal variation in soil and bedrock water contents in terms of regression coefficient magnitude was canal stage. Based on DFA results, a simple regression model was developed to predict soil and bedrock water contents at various elevations as a function of canal stage and net recharge. The performance of the simple model ranged from good ( C eff ranging from 0.56 to 0.74) to poor ( C eff ranging from 0.10 to 0.15), performance was better at sites with smaller depths to water table (

Precision turfgrass management: challenges and field applications for mapping turfgrass soil and stress

Spatial and temporal variation of soil, climate, plants and irrigation requirements are challenges for modern agriculture and complex turfgrass sites. Precision agriculture (PA) evolved to improve site-specific management based on obtaining site-specific information. The focus of this concept paper is on the emerging area of precision turfgrass management (PTM) with attention given to: (a) comparing the concepts of PTM and PA in terms of driving forces and challenges that must be addressed for PTM to progress in science and practice and (b) discussion of specific field mapping applications (purposes) for different turfgrass situations such as golf courses, sod production fields and sports fields. The field applications relate to site-specific management of irrigation, salinity, fertilizer application and cultivation. To illustrate the potential for PTM, different approaches that may be necessary for PTM compared to PA are discussed. The initial factor that hindered the adoption of PTM has been the lack of mobile sensor platforms that can determine both key soil and plant properties for turfgrass situations. This paper concentrates on PTM field applications that involve mapping of both soil and plant attributes, in contrast to only optical sensing mapping.

Temporal variation of soil seed banks in two different dune systems in northeastern Inner Mongolia, China

To assess the potential contribution of soil seed banks to seedling recruitment, and to the vegetative processes of dune systems in semi-arid areas, a comparison of temporal variation in soil seed bank was made between active and stabilized dune systems in northeastern Inner Mongolia, China. The results showed that between-year difference in seed density for the stabilized system was smaller than that for the active one, but there were similar variations with season in seed bank for both dune systems. Furthermore, seed densities of the dominant species on the respective dune type (i.e., annuals on the stabilized dune and psammophytes on the active dune) varied more sharply with season, but more gently in annual variation than those of other phytogroups. These findings suggest that (1) seeds of annuals in the soil of the stabilized dune, or seeds of psammophytes in the soil of the active dune contributed much to seedling recruitment or plant species colonization, (2) the relationship between soil seed bank and seedling recruitment was complex in both dune systems.

A flexible approach to managing variability in grain yield and nitrate leaching at within-field to farm scales

We up-scaled the APSIM simulation model of crop growth, water and nitrogen dynamics to interpret and respond to spatial and temporal variations in soil, season and crop performance and improve yield and decrease nitrate leaching. Grain yields, drainage below the maximum root depth and nitrate leaching are strongly governed by interaction of plant available soil water storage capacity (PAWC), seasonal rainfall and nitrogen supply in the water-limited Mediterranean-type environment of Western Australia (WA). APSIM simulates the interaction of these key system parameters and the robustness of its simulations has been rigorously tested with the results of several field experiments covering a range of soil types and seasonal conditions in WA. We used yield maps, soil and weather data for farms at two locations in WA to determine spatial and temporal patterns of grain yield, drainage below the maximum root depth and nitrate leaching under a range of weather, soil and nitrogen management scenarios. On one farm, we up-scaled APSIM simulations across the whole farm using local weather and fertiliser use data and the average PAWC values of soil type polygons. On a 70 ha field on another farm, we used a linear regression of apparent soil electrical conductivity (ECa) measured by EM38 against PAWC to transform an ECa map of the field into a high resolution (5 m grid) PAWC map. We then used regressions of simulated yields, drainage below the maximum root depth and nitrate leaching on PAWC to upscale the APSIM simulations for a range of weather and fertiliser management scenarios. This continuous mapping approach overcame the weakness of the soil polygons approach, which assumed uniformity in soil properties and processes within soil type polygons. It identified areas at greatest financial and environmental risks across the field, which required focused management and simulated their response to management interventions. Splitting nitrogen applications increased simulated wheat yields at all sites across the field and decreased nitrate leaching particularly where the water storage capacity of the soil was small. Low water storage capacity resulted in both low wheat yields and large leaching loss. Another management option to decrease leaching may be to grow perennial vegetation that uses more water and loses less by drainage.

Soil Change, Soil Survey, and Natural Resources Decision Making

Land managers and policymakers need information about soil change caused by anthropogenic and non-anthropogenic factors to predict the effects of management on soil function, compare alternatives, and make decisions. Current knowledge of how soils change is not well synthesized and existing soil surveys include only limited information on the dynamic nature of soils. Providing information about causes and attributes of soil change and the effects of soil change on soil function over the human time scale (centuries, decades, or less) should be a primary objective of 21st century soil survey. Soil change is temporal variation in soil across various time scales at a specific location. Attributes of change include state variables (dynamic soil properties), reversibility, drivers, trends, rates, and pathways and functional interpretations include resistance, resilience, and early warning indicators. Iterative elements of the blueprint for action described in this article are: (i) identify user needs; (ii) conduct interdisciplinary research and long-term studies; (iii) develop an organizing framework that relates data, processes, and soil function; (iv) select and prioritize soil change data and information requirements; (v) develop procedures for data collection and interpretation; and (vi) design an integrated soil-ecosystem-management information system. Selection of dynamic soil properties, soil change attributes, and functional interpretations to be included in future soil surveys should be based on analyses comparing the benefits of meeting user needs to the costs of data acquisition and delivery. Implementation of the blueprint requires increased collaboration among National Cooperative Soil Survey partners and other research disciplines.

Temporal variations in soil–atmosphere methane exchange after fire in a peat swamp forest in West Siberia

Temporal variations in methane (CH4) exchange between the soil and the atmosphere during a period of 3 years after a forest fire were estimated by combining field measurements of CH4 flux with an analysis of satellite images. The study area was located in a boreal peat swamp forest in the West Siberian plain that experienced a severe fire in the summer of 1998. The surface of the burned area was classified into bare soil, open water and recovered vegetation. In the summers of 1999 and 2000, CH4 fluxes, using a closed-chamber method, and environmental variables, such as soil temperature and soil water content, for each of the three surface types in the burned area and in the unburned area were measured. In general, CH4 fluxes were controlled by the surface moisture in the burned area and by the temperature in the unburned forest. Temporal changes in the areal coverage of soil, water and vegetation in the burned area were investigated using NOAA AVHRR (Advanced Very High Resolution Radiometer) data with subpixel land-cover characterization. Based on the satellite information, temporal changes in the moisture conditions of the burned surface were estimated and temporal variations in the CH4 fluxes for the entire burned area were calculated. The cumulative CH4 emission rates from the entire burned area during the summer (from June to August) were estimated to range from 0.39 to 0.48 g C m−2 during the period from 1999 to 2001. In contrast, unburned forest soils were consistently net CH4 consumers. The cumulative consumption rate during the summer was calculated to be approximately 0.4 g C m−2 based on a reanalysis air temperature dataset. As the surface soil had become extremely wet since the fire, the soil had become a net emitter of CH4 after the fire disturbance, although CH4 oxidation predominated in the unburned forest.

Soil Change, Soil Survey, and Natural Resources Decision Making

Land managers and policymakers need information about soil change caused by anthropogenic and non‐anthropogenic factors to predict the effects of management on soil function, compare alternatives, and make decisions. Current knowledge of how soils change is not well synthesized and existing soil surveys include only limited information on the dynamic nature of soils. Providing information about causes and attributes of soil change and the effects of soil change on soil function over the human time scale (centuries, decades, or less) should be a primary objective of 21st century soil survey. Soil change is temporal variation in soil across various time scales at a specific location. Attributes of change include state variables (dynamic soil properties), reversibility, drivers, trends, rates, and pathways and functional interpretations include resistance, resilience, and early warning indicators. Iterative elements of the blueprint for action described in this article are: (i) identify user needs; (ii) conduct interdisciplinary research and long‐term studies; (iii) develop an organizing framework that relates data, processes, and soil function; (iv) select and prioritize soil change data and information requirements; (v) develop procedures for data collection and interpretation; and (vi) design an integrated soil–ecosystem–management information system. Selection of dynamic soil properties, soil change attributes, and functional interpretations to be included in future soil surveys should be based on analyses comparing the benefits of meeting user needs to the costs of data acquisition and delivery. Implementation of the blueprint requires increased collaboration among National Cooperative Soil Survey partners and other research disciplines.

Seasonal variation in paediatric blood lead levels in Syracuse, NY, USA

Venous blood lead values for 2,633 children aged 0-4 years in Syracuse, New York, collected between 1 April 1992 and 31 March 1993 were summarised by census tract for study of geographic variability. A demographic exposure model is presented showing housing stock and SES (socioeconomic status) parameters as the most significant predictor variables. A seasonal trend in blood lead levels was observed with late summer values about 40% higher than late winter values for census tracts with the highest geometric mean PbB levels. Seasonal variation is compared with a biokinetic uptake model to examine hypotheses about temporal variations in soil and dust lead exposure patterns.

Spatial and Temporal Variation in Soil and Vegetation Impacts on Campsites

We studied the impacts of camping on soil and vegetation at Delaware Water Gap national Recreation Area. We assessed the magnitude of impact on campsites that varied in amount of use and in topographic position. We also evaluated change over a 5‐yr period on long‐established, recently opened, and recently closed campsites, as well as on plots subjected to experimental trampling. Campsite impacts were intense and spatially variable. Amount of use and topographic position explained some of this variation. Soil and vegetation conditions changed rapidly when campsites were initially opened to use and when they were closed to use. Changes were less pronounced on the long‐established campsites that remained open to use. In the trampling experiments, impact varied greatly with trampling intensity and between vegetation types. An open‐canopy grassland vegetation type was much more resistant to trampling than a forb‐dominated forest vegetation type. Campsite impacts increased rapidly with initial disturbance, stabilized with ongoing disturbance, and–in contrast to what has been found in most other studies–decreased rapidly once disturbance was terminated. Implications of these results for campsite management strategies, such as use concentration or dispersal, and rotation or closure of campsites, are discussed.

Topographic Variation of Soil Nitrogen Dynamics at Walker Branch Watershed, Tennessee

Abstract Understanding the spatial and temporal variability of soil nitrogen (N) transformations is central to quantifying the N dynamics and productivity of ecosystems. The objectives of this work were to examine spatial and temporal variation of soil N dynamics and to identify factors correlated with topographic variation in soil N dynamics in a forest watershed. Net N mineralization and net nitrification potential were measured by aerobic laboratory incubations of surface (0-7 cm) mineral soils. Principal components analysis was used to describe sampling sites across the watershed based on 13 site characterization variables. A topographic index used in hydrologic modeling, In (α/tan β), was calculated for each site as the natural logarithm of the ratio of the upslope drainage area per unit contour length (α) to the local slope angle (tan β). Soils from valley floors had greater total N concentrations, lower carbon-to-nitrogen (C:N) ratios, greater potential net nitrification, and greater microbial activity (as indicated by short-term urease assays) than soils from ridges. Mean net nitrification potential was 0.59 μg N g-1 d-1 in surface soils from valley floors and was < 0.01 on ridges and slopes. The first principal component was related to the N and C properties of soils, leaf litter, and leaf fall at a site. The second principal component was related to forest stand composition. The topographic index was significantly correlated with important variables related to soil N dynamics. Once calibration data are derived, this index may be useful as a first approximation to total soil N concentrations and soil C:N ratios in forest watersheds because In (α/tan β) can be calculated from geographic information systems that contain topographic data. For. Sci. 40(3):497-512.

The state of the art in pedometrics

This paper briefly reviews the state of knowledge of the spatial and temporal variation of soil as discussed in the rejoinder session of the Pedometrics Workshop held in Wageningen, 1–3 September 1992. The paper discusses three aspects, namely theory, applications, and tools, in terms of current understanding and the research topics that we should be investigating in the next few years. Future directions for the study of soil variability are discussed in terms of issues for soil survey, issues for modelling, issues for methods and procedures, and finally, issues for effective communication of information about soil variability to users of soil data. An appendix of currently available geostatistical software is also included.

Temporal variation of soil physical properties following moldboard plowing and direct drilling of a sand loam soil

Temporal variation of soil physical properties following moldboard plowing and direct drilling of a sand loam soil