Inherent Soil Research Articles

Concurrent Improvement in Maize Grain Yield and Nitrogen Use Efficiency by Enhancing Inherent Soil Productivity.

Quantifying the relationships of maize yield and nitrogen use efficiency (NUE) to inherent soil productivity (ISP) could provide a theoretical basis for implementing strategies that concurrently narrow the yield gap, increase NUE, and improve soil quality. A field study under irrigation conditions was conducted at five locations with large differences in ISP (estimated by maize grain yield without using fertilizers) across various ecological regions in Inner Mongolia, China. Our results showed that the changes in maize yield and nitrogen partial factor productivity (PFPN) to ISP followed a linear-plateau model, with a common inflection point. When ISP was below 8.0 t ha–1, maize yield and PFPN were stagnating at a low level, due to a trade-off between the contribution of soil and chemical fertilizers to yield. When ISP exceeded 8.0 t ha–1, the contribution rate of soil to yield stabilized at 80%, resulting in a simultaneous increase in maize yield by 1.2 t ha–1 and PFPN by 4.6 kg kg–1, for increasing ISP at each t ha–1. Our results indicated that while keeping other management strategies unchanged, to increase maize yield and PFPN by 15% or further 30%, it is necessary to increase ISP to 9.3 and 10.4 t ha–1, respectively. In this scenario, N input will be reduced by 33.5 and 47.5%, and apparent N losses will be reduced by 11.7 and 21.5%, respectively. Therefore, enhancing ISP could lead to a simultaneous improvement in yield and NUE as well as strongly support the green development of maize production.

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity.

Nitrogen cycling and urban afforestation success inNew York City

Afforestation projects are a growing focus of urban restoration efforts to rehabilitate degraded landscapes and develop new forests. Urban forests provide myriad valuable ecosystem services essential for urban sustainability and resilience. These essential services are supported by natural soil microbial processes that transform organic matter to critical nutrients for plant community establishment and development. Nitrogen (N) is the most limiting nutrient in forest ecosystems, yet little information is known about N cycling in urban afforestation efforts. This study examined microbially mediated processes of carbon (C) and N cycling in 10 experimental afforested sites established across New York City parklands under the MillionTreesNYC initiative. Long-term research plots were established between 2009 and 2011 at each site with low and high diversity (two vs. six tree species) treatments. In 2018, 1-m soil cores were collected from plots at each site and analyzed for microbial biomass and respiration, potential net N mineralization, and nitrification, denitrification potential, soil inorganic N, and total soil N. Field observations revealed markedly different trajectories between sites that exhibited a closed canopy and leaf litter layer derived from trees that were planted and those that did not fit this description. These two metrics served to group sites into two categories (high vs. low) of afforestation success. We hypothesized that: (1) afforestation success would be correlated with rates of C and N cycling, (2) high diversity restoration techniques would affect these processes, and (3) inherent soil properties interact with plants and environmental conditions to affect the development of these processes over time. We found that high success sites had significantly higher rates of C and N cycling processes, but low and high diversity treatments showed no differences. Low success sites were more likely to have disturbed soil profiles with human-derived debris. Afforestation success appears to be driven by interactions between initial site conditions that facilitate plant community establishment and development that in turn enable N accumulation and cycling, creating positive feedbacks for success.

Plant growth, soil properties, and microbial community four years after thermal desorption

AbstractThe effects of thermal desorption (TD) on soil physical and chemical properties after crude oil contamination are recently well studied. However, there are limited field‐scale studies on long‐term soil biological property recovery such as microbial communities and plant growth, which are vital for meeting global agrosystem demands and restoring ecosystem health. This study describes the status of soil biological properties after 4 yr of crop production on oil‐contaminated cropland remediated via TD and a modified land farming technique. Plots were constructed in 2015 with native, uncontaminated topsoil (A); TD‐treated subsoil (TDU); untreated land‐farmed subsoil (SP); TDU + A (TDA), and SP + A (SPA) where soil ratios were 1:1 by volume, and composted manure (CM) was applied at 40 Mg ha‐1. After 3 yr of crop production (2019) grain sorghum [Sorghum bicolor (L.) Moench] was planted. Soil microbial community characteristics were assessed through phospholipid fatty acid analysis and by estimating mycorrhizal root colonization. Notably, inherent soil chemical and physical properties influenced the recovery of microbial communities in remediated soils. However, sorghum biomass production in TDU was 50 ± 9% greater than SP while the microbial abundance in these treatments remained similar. Mycorrhizal colonization variation likely reflected rhizosphere nutrient scarcity and not the interactions of either remediation strategy. Based on these results after 4 yr of cropping, TDU does not diminish soil microbial recovery, and when possible, blending TDU materials with topsoil provides the greatest level of recovery relative to topsoil only.

Assessing the Suffusion Susceptibility of the Homogeneous Earth Dam Body Considering Spatial Variability of Soil Properties

The suffusion susceptibility of the soil samples is evaluated through an erosion resistance index. The erosion resistance index is estimated from several soil parameters thanks to existing statistical analyses. In actual exploitation, the soil properties with the input parameters are related to the grain distribution of the soil. Vary greatly from the original design value due to the influence of many factors. One of the factors is the inherent variability. Inherent soil variability is modeled as a random field. The usual problems used to assess the suffusion susceptibility maybe not give accurate results or fully evaluate the actual working ability of the ground in each case. That is one of the reasons why dams are still eroded when they are put into use. The paper aims to assess the suffusion susceptibility of the earth dam body using a two-dimensional (2D) Stochastics random field, modeling the initial problem, considering the variability spatial of soil properties, using the assumption of a Normal random field of soil characteristics parameters. The research goals predict the two-dimensional spatial variability of erosion resistance index of the dam body, probability of suffusion susceptibility, and the variability spatial of density and internal friction angle. An illustration of a numerical simulation of a homogeneous earth dam body is presented in this paper. The scientific novelty of the paper shows the predicted results of the two-dimensional spatial variability of erosion resistance index with a contour map and probability of suffusion susceptibility of the homogeneous earth dam body. Furthermore, the two-dimensional spatial variability maps of density and internal friction angle are also shown.

Development and spatialization of a soil potential multifunctionality index for agriculture (Agri-SPMI) at the regional scale. Case study in the Occitanie region (France)

Europe is faced to a competing demand for areas suitable for agriculture and areas suitable for urban development. To help building the general guidelines necessary for a sustainable development at the regional scale, we developed a soil potential multifunctionality index for agriculture (Agri-SPMI), which used the concepts of soil-based ecosystem services and soil functions. It considered the provision of a physical and chemical habitat for plant growth functions, the retention and transfer of water and pollutants function, and the carbon storage function. Three agricultural land uses were considered in this index: arable lands, perennial crops, and pastures. The assessment of the Agri-SPMI was done over a large territory, using a small set of inherent soil properties available in the French soil survey database at 1:250,000 scale. The output was in the form of two maps, which can be viewed in a GIS software: a map of areas with high Agri-SPMI and a map of the service of food, biomass, and fiber production. The concept of soil multifunctionality allowed highlighting environmental issues related to agriculture and to encourage land planners to take them into account in addition to the agronomic potential of soils. The framework used is fully transferable to other scales, other soil contexts, or other ecosystem services, with adaptation of the soil properties considered.

Numerical Modelling of Shallow Foundations on Expansive Shale: A Case Study of Jamshoro, Pakistan

This study analyzes expansive soil swelling under the shallow foundation using the Plaxis 2D FEM software. Under the impact of changing water conditions, expansive soil undergoes obvious volumetric changes, which often cause differential movements of the shallow foundations resting on it, which may lead to structural damage if no special precautions had been taken during the design process. In previous studies, the swelling of soil was simulated in Plaxis by applying the swelling potential with a positive volumetric strain, without considering water level changes, which proved to be not practical. This study demonstrates the time-dependent deformation (swelling) in expansive soil using the Plaxis 2D user-defined Swelling Rock Model in different soil and parametric conditions. The geotechnical properties of expansive shale were determined in the laboratory and by field testing, using parameters of the collected soil as input for the numerical model. Swelling of soil increased due to the increase of water level and decreased with the load. The heave was minimum in the center of the foundation (20 mm), attaining the maximum value at the corner (16 cm). The increase in the modulus of elasticity does not have much effect on soil swelling compared to soil settlement. The effect of matric suction-related changes on the swelling of soil due to the rise of the water table is not significant compared to the inherent soil swelling behaviour.

Soil health practices have different outcomes depending on local soil conditions

The amount of soil organic matter is a critical indicator of soil health. Applying compost or manure, growing cover crops, reducing tillage, and increasing crop diversity may increase soil organic matter. However, soil organic matter can vary dramatically in different environments, regardless of management practices. This calls for a framework to recommend place-based soil health practices and evaluate their outcomes. We used a new framework that groups soil survey data into seven regions in California's Central Valley and Central Coast. These regions either have performance limitations, such as root restrictive horizons, salinity, and shrink-swell behavior, or have relatively homogeneous, coarse-to-loamy soils ideal for agriculture. These inherent conditions affect a soil's response to practices designed to improve soil health. Looking at vineyards as an example, we find significant soil organic matter contrasts between soil health regions but not among contrasting management approaches within a given region. We also show that conservation practices improve or help maintain soil health in several long-term experiments, but inherent soil properties and types of cropping systems affect outcomes.

Contrasting changes in soil carbon under first rotation, secondary and historic woodland in England and Wales

This study investigates changes in soil carbon under woodland combining data from the National Soil Inventory of England and Wales with data from the National Inventory of Woodlands and Trees to create a unique dataset with woodland management information at the sites where soil carbon was measured in 1980 and 2003. Three woodland management stages were compared: first rotation (i.e. recently planted on land not previously under woodland and not yet harvested), second rotation (i.e. harvested at least once), and historic woodlands. Woodlands in their first rotation demonstrated a reduction (p < 0.01) in topsoil organic carbon content typically losing over 2% per year, whereas no change (p ≥ 0.10) was observed for the other two woodland types. This large reduction in organic carbon could not be statistically explained by a higher inherent soil carbon, as the mean soil carbon content of the first rotation and second rotation woodlands were not (p ≥ 0.50) different. The average age of the woodlands under first rotation was 42 years, indicating that the period of significant soil carbon loss could go on for about 40 years after planting.

Biological invasions and climate change amplify each other’s effects on dryland degradation

Climate models predict that, in the coming decades, many arid regions will experience increasingly hot conditions and will be affected more frequently by drought. These regions are also experiencing rapid vegetation change, notably invasion by exotic grasses. Invasive grasses spread rapidly into native desert ecosystems due, in particular, to interannual variability in precipitation and periodic fires. The resultant destruction of non-fire-adapted native shrub and grass communities and of the inherent soil resource heterogeneity can yield invader-dominated grasslands. Moreover, recurrent droughts are expected to cause widespread physiological stress and mortality of both invasive and native plants, as well as the loss of soil resources. However, the magnitude of these effects may differ between invasive and native grasses, especially under warmer conditions, rendering the trajectory of vegetated communities uncertain. Using the Biosphere 2 facility in the Sonoran Desert, we evaluated the viability of these hypothesized relationships by simulating combinations of drought and elevated temperature (+5°C) and assessing the ecophysiological and mortality responses of both a dominant invasive grass (Pennisetum ciliare or buffelgrass) and a dominant native grass (Heteropogan contortus or tanglehead). While both grasses survived protracted drought at ambient temperatures by inducing dormancy, drought under warmed conditions exceeded the tolerance limits of the native species, resulting in greater and more rapid mortality than exhibited by the invasive. Thus, two major drivers of global environmental change, biological invasion and climate change, can be expected to synergistically accelerate ecosystem degradation unless large-scale interventions are enacted.

Determination of soil fertility constraints in two paddy soils of the western highland zone of Cameroon

Information on soil fertility status and variability are essential in understanding the potential of soils and their management interventions in agriculture. The present study aimed at examining the soil quality or fertility of two paddy soils with different productivity in the Western Highland Zone of Cameroon. Twelve soil samples were collected in each of both study location at a standard depth of 0-30 cm and analyzed to find soil texture, Organic Carbon (OC), basic cations (Calcium Ca, Magnesium Mg, Potassium K and Sodium Na), Cation Exchange Capacity (CEC), soil pH, phosphorus (P), and Total Nitrogen (TN). Most measured soil characteristics showed different degrees of variability in soil nutrients ranging from low to very high in both soils. Both soils were acidic (pH &lt;5.5), consistently deficient in total nitrogen, phosphorus, basic cations, and had high OC and CEC. Pearson correlation analysis and principal component analysis were used to identify appropriate soil quality indicators. P and Na in Koutaba and P, Mg, and CEC in Santchou constituted minimum data set (MDS) and accounted for 94% and 100% of the quality variation among soils. A Soil Quality Index (SQI) was developed base on the MSD method, Santchou and Koutaba received SQI of 0.48 and 0.73. The paddy soils of Koutaba were more fertile than those of Santchou. The low level of P and Mg were considered to be the major constraints limiting the productivity in both locations. These results suggest that, the management of inherent soil properties is based on-site specific situations.

Root‐zone enrichment of carbon, nitrogen, and soil‐test biological activity under cotton systems in North Carolina

AbstractSoils of the southeastern United States are generally low in organic matter. Root‐zone enrichment of organic carbon (C) and nitrogen (N) may be possible with conservation agricultural management, but little is known of how this might be distributed across private farms. A stratified random survey of 120 cotton (Gossypium hirsutum L.) fields from throughout North Carolina characterized root‐zone contents of soil organic C (SOC), total soil N (TSN), and soil‐test biological activity (STBA). Soils were mostly udults and aquults, but included some udepts, aquepts, aqualfs, and psamments. Depth distribution of soil properties at 0–10, 10–30, and 30–60 cm was fitted to a nonlinear regression model for each soil profile to calculate root‐zone enrichment over that of a baseline content estimated from concentration at 30‐cm depth. Continuous conservation tillage was practiced on 23% of fields. Root‐zone enrichment of TSN and STBA was greater with conservation than with disk tillage (1.30 ± 0.10 vs 0.82 ± 0.04 Mg N ha–1, respectively, p &lt; .001; 209 ± 16 vs 144 ± 6 kg CO2–C ha–1 3 d–1, respectively; p &lt; .001) (mean ± standard error). Difference in root‐zone enrichment of SOC between continuous conservation tillage and frequent disk tillage was 8.5 ± 2.5 Mg C ha–1 among eight subregions and was not affected by variations in baseline SOC content, which was greater in the Flatwoods than the Coastal Plain region due to inherent soil formation factors. These on‐farm results confirm that continuous conservation tillage is needed to enrich root‐zone SOC, TSN, and STBA under cotton production.

Productivity and Nutrient Balance of an Intensive Rice-Rice Cropping System Are Influenced by Different Nutrient Management in the Red and Lateritic Belt of West Bengal, India.

Rice is the lifeline for more than half of the world population, and in India, in view of its huge demand in the country, farmers adopt a rice–rice cropping system where the irrigation facility is available. As rice is a nutrient-exhausting crop, sustainable productivity of rice–rice cropping system greatly depends on appropriate nutrient management in accordance with the inherent soil fertility. The application of an ample dose of fertilizer is the key factor for maintaining sustainable rice yields and nutrient balance of the soil. Considering the above facts, an experiment was conducted on nutrient management in a rice–rice cropping system at the university farm of Visva-Bharati, situated in a sub-tropical climate under the red and lateritic belt of the western part of West Bengal, India, during two consecutive years (2014–2016). The experiment was laid out in a Randomized Completely Block Design with 12 treatments and three replications, with different rates of N:P:K:Zn:S application in both of the growing seasons, namely, kharif and Boro. The recommended (ample) dose of nutrients was 80:40:40:25:20 and 120:60:60:25:20 kg ha−1 of N:P2O5:K2O:Zn:S in the Kharif and Boro season, respectively. A high yielding variety, named MTU 7029, and a hybrid, Arize 6444 GOLD, were taken in the Kharif and Boro seasons, respectively. The results clearly indicated that the application of a recommended dose of nutrients showed its superiority over the control (no fertilizer application) in the expression of growth characters, yield attributes, yields, and nutrient uptake of Kharif as well as Boro rice. Out of the all treatments, the best result was found in the treatment where the ample dose of nutrients was applied, resulting in maximum grain yield in both the Kharif (5.6 t ha−1) and Boro (6.6 t ha−1) season. The corresponding yield attributes for the same treatment in the Kharif (panicles m−2: 247.9; grains panicle−1: 132.0; spikelets panicle−1: 149.6; test weight: 23.8 g; and panicle length: 30.6 cm) and Boro (panicles m−2: 281.6; grains panicle−1: 142.7; spikelets panicle−1: 157.2; test weight: 24.8 g; and panicle length: 32.8 cm) season explained the maximum yield in this treatment. Further, a reduction or omission of individual nutrients adversely impacted on the above traits and resulted in a negative balance of the respective nutrients. The study concluded that the application of a recommended dose of nutrients was essential for proper nutrient balance and sustainable yields in the rice–rice cropping system.

Cropping system and soil texture shape soil health outcomes and scoring functions

Inherent soil properties often define the soil's basic functions, but human management can have superimposing impacts on the quality of soil. It is therefore challenging to interpret Soil Health (SH) measurements in the context of a region's soils and cropping systems. We examined the effects of soil texture, a dominant inherent soil property, and cropping system on SH indicators for New York, USA soils. A dataset of 1,750 soil samples was analyzed for SH indicators including Soil Organic Matter (SOM), Permanganate-Oxidizable Carbon (POXC), Soil Respiration (Resp), soil protein (Protein), Available Water Capacity (AWC), Wet Aggregate Stability (WAS), surface and subsurface penetration resistance, and seven soil chemical properties. Measured physical and biological indicators were affected by both soil texture and cropping system. AWC measured on disturbed samples was mostly affected by texture (37.4% variance explained), while Resp, Protein, and WAS were mostly impacted by cropping system (11.7%, 14.7%, and 22.1% variance explained, respectively). POXC was equally affected by texture and cropping system. Pasture and Mixed Vegetable systems tended to have the highest biological and physical soil health, followed by Dairy Crop systems. Annual Grain and Processing Vegetable cropping systems tended to have the lowest soil health. The effects of cropping systems are presumably linked to differences in the carbon and nutrient balances and the amount of soil disturbance through tillage. New scoring functions based on soil texture classes and cropping systems were developed for New York State to facilitate interpretation of SH test results in the context of the production-specific environments.

Optical sensors to predict sugarbeet yield, quality, and fertilizer nitrogen application rate

Nitrogen (N) management is critical for sugarbeet (Beta vulgaris L.) because N inversely influences root yield and recoverable white sucrose per tonne (RWST). In Ontario, from 2015 to 2017, the use of optical sensors (e.g., a soil plant analysis development (SPAD) chlorophyll meter, GreenSeeker handheld crop sensor) was evaluated as a method to guide N application and harvest date (late-September, late-October) selection by predicting root yield RWST and partial profit margins. In a commercial field, 4 to 5 fertilizer N rates, and 8 to 12 cultivars were tested in a split block design experiment with three replications and two harvest dates. In all years, few cultivars (≤2) had a root yield response to applied N, which was attributed to high inherent soil fertility, and limited our evaluation of optical sensors to adjust in-season N applications. The optimal N rate to maximize RWST and profits was 0 to 45 kg N·ha−1 and confirmed their negative relationship to applied N. Optical sensor readings correlated negatively with RWST across the majority (&gt;60%) of cultivars tested in mid-August and September. Across all cultivars, the regression model of optical sensors to predict RWST at early harvest was strongest (R2 = 0.48 for SPAD; 0.24 for GreenSeeker) when readings were taken in early September. Although future research to refine this relationship is needed, we recommend the use of optical sensors, particularly the SPAD meter, in early September to guide harvest selection to maximize RWST.

Soil spatial variability characterization: Delineating index-based management zones in salt-affected agroecosystem of India

Farm level recommendation in salt-affected agricultural landscapes is practically difficult due to spatial variations in inherent soil salinity, diverse farming situations and associated land ownerships with small-scale production systems. This study presents spatial array analysis of 354 geo-referenced soil samples revealing widespread heterogeneity in soil sodicity and fertility status across salt-affected Ghaghar basin of Kaithal district in Haryana, India. Six principal components accounted for 73% of the total variability, and the most important contributors [electrical conductivity (ECe), sodium adsorption ratio (SAR), DTPA extractable copper (Cu) and boron (B), soil organic carbon (OC) and available phosphorus (AP)] as minimum data set were used to develop the soil quality index (SQI). Geostatistical analysis revealed Circular (ECe and AP), Exponential (SAR, OC and B) and Gaussian (Cu) as the best fit semivariogram ordinary kriging model with weak to moderate spatial dependence. Three soil management zones (SMZs) were delineated by grouping the entire area based on soil quality index (SQI). Fertilizer recommendations for rice-wheat cropping system in different SMZs were calculated using soil test crop response (STCR) equation to ensure balanced fertilization, resource saving and reducing environmental footprints. Gypsum requirement map was prepared for systematic allocation and distribution, and enabling farmers to precisely use the mineral gypsum in order to reclaim and reduce stresses led by sodic lands. The implications of this study showed zone-specific advocacy for gypsum application (as soil ameliorant) and balanced fertilization in sustainable restoration of sodic lands, improving nutrient use efficiency and stabilizing crop production in salt-affected regions of India and similar ecologies elsewhere.

Estimating Soil Loss for Sustainable Crop Production in the Semi-deciduous Forest Zone of Ghana

Quantitative information on soil loss is relevant for devising soil conservation and crop management strategies to ensure sustainable fertility management and crop production. Estimations from runoff/erosion plots are expensive and laborious and thus requiring the exploration of other less expensive but reliable methods such as modeling. This study aimed to estimate current and future rates of soil loss for conservation planning toward sustainable crop production in the semi-deciduous forest zone of Ghana. The Universal Soil Loss Equation (USLE), which took into consideration the rainfall characteristics of the study area, inherent soil physicochemical and hydraulic properties, variations in slopes and terrain differences, land cover types, and soil management practices, was employed to estimate the magnitude and rate of soil loss in the study area. Output from three regional climate models (RCMs) from Coordinated Regional Climate Downscaling Experiment including CCCma-CanESM2, GFDL-ESM2M, and HadGEM2-ES were used to estimate the impact of climate change on soil erosion in the study area. The results showed that soil loss estimated for bare soils was high ranging from 12.7 to 163.8 t ha−1 year−1 largely due to variation in slopes coupled with soil physicochemical and hydraulic properties. The simulated annual soil losses under various land cover options showed variable degrees of soil loss for maize cultivation under conventional tillage (8.2–106.5 t ha−1 year−1), soya bean monocropping (4.4–57.3 t ha−1 year−1), and low soil loss for oil palm plantation with grass or leguminous cover (2.5–32.8 t ha−1 year−1). Evaluation of the RCMs showed excellent performance for CCCma-CanESM2 and GFDL-ESM2M. Predictions of climate change impact using outputs from CCCma-CanESM2 and GFDL-ESM2M indicated that 9–39% increase in soil loss is expected by 2070, and it will be more severe (16–42%) by 2100. The model predictions indicate that the adoption of site-specific land cover management strategies such as tree–cover crop intercropping and reduced tillage has a huge potential to reduce soil loss and sustain soil fertility. The model can be used as an advisory tool for mapping areas for appropriate cropping systems for a particular site.

Wood stake decomposition twenty years after organic matter removal at the Lake States LTSP sites

Organic matter (OM) is an integral part of site productivity for a forest, and understanding the effects of OM removal on various forms of carbon (C) cycling is important for land managers and for policy makers. In this study, we utilized the Lake States Long-Term Soil Productivity (LTSP) study sites, located along a gradient in soil texture (clay, silt loam and sand) and high to low productivity, to evaluate the impacts of two OM removal treatments on belowground wood decomposition. In 2013, approximately 20 years after the LTSP treatments had been installed, we placed standardized aspen and loblolly pine wood stakes in the mineral soil of plots receiving the bole only harvesting treatment (BO) and the whole tree harvesting with forest floor removal treatment (WT + FF), and in plots in an adjacent unharvested reference area (1350 wood stakes total). Soil was also sampled to characterize the microbial community composition in the various treatments. From 2014 to 2018, wood stakes were removed from each treatment, and mass loss determined. We found significant differences in wood stake decomposition among the three sites, and between the two wood species, but little impact of timber harvesting and surface OM removals on decomposition. Soil microbial composition also reflected site differences in stake decomposition. We conclude that clearcut harvest and surface OM removal had little effect on stake mass loss in the mineral soil 20 years after the treatments were initiated, and the inherent soil factors are now controlling decomposition.

(IMCS Second Place Best Paper Winner) Investigation of Room Temperature Ionic-Liquid (RTIL) Modified Electrode for Decoupling Soil Electrochemistry

Room temperature ionic liquid (RTIL) is a unique zwitter-ionic compound, that possesses excellent physical and chemical properties, which enables electrochemical applications such as to be utilized as a transducer for probing a complex matrix such as soil. The wide electrochemical window and elevated double layer capacitance of RTIL helps to gauge soil parameters which is helpful to understand soil state. In this work we investigate the utility of RTIL modified electrodes as viable sensors for decoupling soil electrochemistry. Soil plays the key role in plant and crop production and is a vital parameter in the ecological structure of the planet and indispensable in the food ecosystem cycle. Soil health monitoring in the near past has been highly qualitative and speculative with more recent advancements still trying to fill the void of a holistic soil profile. In fields and crop-circles, testing methods to perform in-situ profiling however from one lab is likely to vary with another and hence results are not universally compatible. Additionally, these normalized techniques ideally involve empirical approaches, extensive sample preparation which adds on to a temporal factor along with equipment for extraction and subsequently-analysis. This therefore-stimulates the need for a testing methodology that is capable of rapid analysis in an in-situ environment that can be applicable universally.In this paper, we focus on: a rapid electrochemical point probing mechanism that acts as a soil state evaluation platform via a 3-electrode sensor modified by a widely characterized-RTIL [BMIM] [BF4] interfacial transducer medium. The proposed quantitative model –‘DENSE’ probes the soil diffuse double layer (DDL) dielectric to evaluate a thorough chemical profile of the soil matrix. The experimental design was implemented to capture the effect of electroactive species in the soil matrix altered by adding nutritional amendments. Non-faradaic probing was then performed in this design to gauge the inherent capacitive modulations of the soil system as a function its compositional changes. Therefore, by looking at the rate of electrochemical activity and inherent soil dielectric changes driven by an RTIL interfacial layer, it is possible to decouple information on nutrient availability in soils with potential for application towards temporal soil analysis.Figure: (A) Equivalent-circuit (DENSE) model of the soil-water matrix and a schematic representation of the model with respect to the electrode-electrolyte interface (B) Impedance nyquist plot and (C) Bode-phase to denote the pseudo-capacitive dominant nature of the soil matrix (1:1, 1:2) and the comparatively resistive behavior of the baseline and 2:1 mixture Figure 1

Chemical and molecular scale speciation of copper, zinc, and boron in agricultural soils of the Canadian prairies

The general incidence of copper (Cu), zinc (Zn), and boron (B) deficiencies in soils of the Canadian prairies may be related to identifiable, highly variable, inherent soil attributes. The objective of this study was to investigate the variability of selected properties and their relationship with the bioavailability, forms, and distribution of Cu, Zn, and B in a range of prairie soils. The nature of these micronutrient distributions were evaluated by measuring extractable concentrations, supply rates, and by separation into various chemical pools through sequential extraction and spectroscopic speciation analyses. Soil pH was found to be the least variable property [coefficient of variation (CV) &lt; 13%], whereas carbonate content was the most variable (CV &gt; 130%). The Cu and B availability showed strong negative correlation with the sand content in all soils. Path coefficient results indicated that organic carbon had the highest positive direct effect on availability and supply of Cu and B in Grey soils. Extractable Zn was positively correlated with organic carbon content of Brown and Dark Brown soils. Overall, high sand content and low organic matter were identified as important soil properties contributing to the deficiency of Cu, Zn, and B. The major proportion of Cu, Zn, and B was found in the recalcitrant residual fraction (59%–88%), with the smallest proportions in labile soluble, exchangeable forms (2%–8%). The X-ray absorption near edge structure revealed that Cu and Zn associated with carbonate minerals were dominant forms of these micronutrients present in all soils. Chemisorption is likely a major process regulating the bioavailability of Cu and Zn in prairie soils.