Significance Of Soil Research Articles

Rapid Analysis of Soil Organic Carbon in Agricultural Lands: Potential of Integrated Image Processing and Infrared Spectroscopy

The significance of soil in the agricultural industry is profound, with healthy soil representing an important role in ensuring food security. In addition, soil is the largest terrestrial carbon sink on earth. The soil carbon pool is composed of both inorganic and organic forms. The equilibrium of the soil carbon pool directly impacts the carbon cycle via all of the other processes on the planet. With the development of agricultural systems from traditional to conventional ones, and with the current era of precision agriculture, which involves making decisions based on information, the importance of understanding soil is becoming increasingly clear. The control of microenvironment conditions and soil fertility represents a key factor in achieving higher productivity in these systems. Furthermore, agriculture represents a significant contributor to carbon emissions, a topic that has become timely given the necessity for carbon neutrality. In addition to these concerns, updating soil-related data, including information on macro and micronutrient conditions, is important. Carbon represents one of the major nutrients for crops and plays a key role in the retention and release of other nutrients and the management of soil physical properties. Despite the importance of carbon, existing analytical methods are complex and expensive. This discourages frequent analyses, which results in a lack of soil carbon-related data for agricultural fields. From this perspective, in situ soil organic carbon (SOC) analysis can provide timely management information for calibrating fertilizer applications based on the soil–carbon relationship to increase soil productivity. In addition, the available data need frequent updates due to rapid changes in ecosystem services and the use of extensive fertilizers and pesticides. Despite the importance of this topic, few studies have investigated the potential of image analysis based on image processing and spectral data recording. The use of spectroscopy and visual color matching to develop SOC predictions has been considered, and the use of spectroscopic instruments has led to increased precision. Our extensive literature review shows that color models, especially Munsell color charts, are better for qualitative purposes and that Cartesian-type color models are appropriate for quantification. Even for the color model, spectroscopy data could be used, and these data have the potential to improve the precision of measurements. On the other hand, mid-infrared radiation (MIR) and near-infrared radiation (NIR) diffuse reflection has been reported to have a greater ability to predict SOC. Finally, this article reports the availability of inexpensive portable instruments that can enable the development of in situ SOC analysis from reflection and emission information with the integration of images and spectroscopy. This integration refers to machine learning algorithms with a reflection-oriented spectrophotometer and emission-based thermal images which have the potential to predict SOC without the need for expensive instruments and are easy to use in farm applications.

Performance Evaluation and Comparison of Deep Neural Network Models for African Soil Properties Prediction

ABSTRACT The significance of soil in agriculture and human survival cannot be overstated. Given its limited supply, improving soil properties is imperative. This study addresses this challenge by predicting five major soil properties—organic carbon, pH values, Mehlich-3 extractable calcium, Mehlich-3 extractable phosphorus, and sand content—utilizing mid-infrared absorbance measurements from the African Soil Information Service (AfSIS) dataset, covering non-desert regions of Africa. With a pressing need for a reliable and efficient model to predict African soil properties using spectral measurements, this study fills a crucial gap, addressing the scarcity of functional soil property databases in Africa. The developed model eliminates costly soil sample preparation and lengthy chemical analysis, applicable in both onsite and laboratory settings for determining soil functional properties. By employing stacked autoencoders for feature dimensionality reduction and combining discrete wavelet transform with two feature selection methods (stepwise regression and random forest) to build robust multi-layer perceptron (MLP) models, the study offers a comprehensive approach. Evaluation metrics including root mean square error (RMSE), scatter index (SI), Variance Accounted For (VAF), Nash-Sutcliffe Model Efficiency (NSE), and Correlation Coefficient (R) demonstrate the superior performance of the MLP model informed by stacked autoencoder-selected features, outperforming models informed by wavelet-transformed features and partial least square regression. This best-performing autoencoder-based model presents a valuable tool for soil scientists tasked with modeling African soil properties.

Effect of soil hydrophobicity on soil-water retention curve of a silt loam soil

Soil wettability is an important property that affects the behaviour of fine-grained soils. Previous studies have shown that hydrophobicity induced by organic or silane additives may affect the soil-water retention curve (SWRC). However, current findings regarding the effect of hydrophobicity on the SWRC are controversial. Previously, organic or silane additives were assumed to change only the soil wettability. Nevertheless, this study shows that polyvinyl alcohol (PVA) can change the hydrophobicity, pore size distribution (PSD), and specific surface area (SSA) of soil, thus affecting the SWRC. PVA-treated soil is hydrophobic when cured at 20 ℃, but hydrophilic when cured at 100 ℃. No thermal degradation is indicated in the PVA at 100 ℃ based on thermogravimetric analysis and a comparison of mass loss, and the sole difference between the PVA-treated soils cured at 20 and 100 ℃ is their wettability. This study managed to make the hydrophobicity caused by PVA to become an independent variable separated from the PSD and SSA by controlling the ambient temperature. The wetting and drying curves are measured under isopiestic humidity control in the high-suction domain (2.7–298.7 MPa), whereas pressure plates are used for the drying curves in the low-suction domain (0–800 kPa). The results obtained indicate that soil hydrophobicity significantly accelerates drainage when the matric suction is between 100 and 400 kPa, and an increase in PVA content increases the water retention capacity of soil. When the matric suction exceeds 2.7 MPa, the effect of soil hydrophobicity on the SWRC of the soil weakens. At this time, the SWRC is dominated by the van der Waals force, and the SSA contributes significantly to the process. Additionally, this study enables some controversial findings from previous studies to be explained, which is of great significance in soil and agriculture sciences.

Aerobic and denitrifying methanotrophs: Dual wheels driving soil methane emission reduction

The greenhouse gas methane in soils has been considered to be consumed mainly by aerobic methane-oxidizing bacteria for a long time. In the last decades, the discovery of anaerobic methanotrophs greatly complemented the methane cycle, but their contribution rates and ecological significance in soils remain undescribed. In this work, the soil samples from forest, grassland and cropland in four different climatic regions were collected to investigate these conventional and novel methanotrophs. A dual-core microbial methane sink, responsible for over 80 % of soil methane emission reduction, was unveiled. The aerobic core was performed by aerobic methanotrophic bacteria in topsoil, who played important roles in stabilizing bacterial communities. The anaerobic core was denitrifying methanotrophs in anoxic soils, including denitrifying methanotrophic bacteria from NC10 phylum and denitrifying methanotrophic archaea from ANME-2d clade. They were ubiquitous in terrestrial soils and potentially led to around 50 % of the total methane removal. Human activities such as livestock farming and rice cultivation further promoted the contribution rates of these denitrifying methanotrophs. This work elucidated the emission reduction contribution of different methanotrophs in the continental setting, which would help to reduce uncertainties in the estimations of the soil methane emission.

Conditional filamentation as an adaptive trait of bacteria and its ecological significance in soils

Conditional filamentation as an adaptive trait of bacteria and its ecological significance in soils

'Only One Earth' – Celebrating soil science on World Environment Day 2022

'Only One Earth' – Celebrating soil science on World Environment Day 2022

Calculation of Mineralogical and Chemical Weathering Indices (Xd, MIA and CIA) and their Significance in Soils at Selected Areas in Northern Iraq

Calculation of Mineralogical and Chemical Weathering Indices (Xd, MIA and CIA) and their Significance in Soils at Selected Areas in Northern Iraq

Conditional filamentation as an adaptive trait of bacteria and its ecological significance in soils.

Bacteria can regulate cell morphology in response to environmental conditions, altering their physiological and metabolic characteristics to improve survival. Conditional filamentation, in which cells suspend division while continuing lateral growth, is a strategy with a range of adaptive benefits. Here, we review the causes and consequences of conditional filamentation with respect to bacterial physiology, ecology and evolution. We describe four major benefits from conditional filamentation: stress tolerance, surface colonization, gradient spanning and the facilitation of biotic interactions. Adopting a filamentous growth habit involves fitness trade-offs which are also examined. We focus on the role of conditional filamentation in soil habitats, where filamentous morphotypes are highly prevalent and where environmental heterogeneity can benefit a conditional response. To illustrate the use of information presented in our review, we tested the conditions regulating filamentation by the forest soil isolate Paraburkholderia elongata 5NT . Filamentation by P. elongata was induced at elevated phosphate concentrations, and was associated with the accumulation of intracellular polyphosphate, highlighting the role of filamentation in a phosphate-solubilizing bacterium. Conditional filamentation enables bacteria to optimize their growth and metabolism in environments that are highly variable, a trait that can impact succession, symbioses, and biogeochemistry in soil environments.

Spatial distribution of fallout and lithogenic radionuclides controlled by soil carbon and water erosion in an agroforestry South-Pyrenean catchment

The mineral composition of soils and weathering processes are known to control the natural radioactivity of soils but research on the influence of water erosion and of main soil properties in the spatial variability of lithogenic and fallout radionuclides remains little investigated in heterogeneous agroecosystems with complex landscape. An extensive study was conducted to determine the mass activities of fallout (137Cs, 210Pbex) and lithogenic radionuclides (238U, 226Ra, 232Th, 40K) an assess the main controls affecting their spatial variations in a representative 2.5 km2 Pre-Pyrenean catchment of north-eastern Spain. The complex agroforestry catchment holds two distinctive parent materials, Muschelkalk limestones and Keuper argillaceous marls, in which the variability of the main soil properties and soil erosion patterns are well characterised. A total of 228 soil samples have been measured by using a high-purity germanium detector. Lithological influence on the variability of radionuclides was investigated and our results indicate that there are strong significant differences between the mass activities of 137Cs, 210Pbex, 226Ra and 40K based on the two different parent materials. Positive correlations were found among the radioactivity contents of 232Th and 40K and the clay content. Total organic carbon (SOC) was also positively correlated with 137Cs, 210Pbex and 226Ra activities, whereas carbonate content and SIC were negatively correlated with the radionuclides with higher significance in soils on limestones.To gain knowledge on the spatial variability of the radionuclides within the landscape, maps of the distribution of radionuclides were generated by GIS interpolation tools of the entire set of measured activities and soil properties within a 100 × 100 m grid. The spatial patterns obtained, besides the variations of radionuclides along four selected transects, confirm the key role of water erosion in the mobilisation of fallout radionuclides, especially 137Cs, while lithogenic radionuclides were sensitive to physical processes in areas where soil loss was intense. This study not only filled the gap of radioactivity data in agroforestry systems with contrasting parent materials, but also shed light on the potential of radionuclides for tracking soil redistribution processes in fingerprints studies.

Detection of tyrosine, trace metals and nutrients in cow dung: the environmental significance in soil and water environments

This study examined the dissolved organic matter (DOM) components of cow dung using a combination of fluorescence (excitation–emission matrix, EEM) spectroscopy and parallel factor (PARAFAC) modelling along with eleven trace metals using ICP-MS and nutrients (NH4+ and NO3−) using an AA3 auto analyser. EEM–PARAFAC analysis demonstrated that cow dung predominantly contained only one fluorescent DOM component with two fluorescence peaks (Ex/Em = 275/311 nm and Ex/Em = 220/311 nm), which could be denoted as tyrosine by comparison with its standard. Occurrence of tyrosine can be further confirmed by the FTIR spectra. Trace metals analysis revealed that Na, K and Mg were significantly higher than Ca, Fe, Mn, Zn Sr, Cu, Ni and Co. The NH4+ concentrations were substantially higher than NO3−. These results thus indicate that the dissolved components of the cow dung could be useful for better understanding its future uses in various important purposes.

Modelling soil moisture in a high‐latitude landscape using LiDAR and soil data

AbstractSoil moisture has a pronounced effect on earth surface processes. Global soil moisture is strongly driven by climate, whereas at finer scales, the role of non‐climatic drivers becomes more important. We provide insights into the significance of soil and land surface properties in landscape‐scale soil moisture variation by utilizing high‐resolution light detection and ranging (LiDAR) data and extensive field investigations. The data consist of 1200 study plots located in a high‐latitude landscape of mountain tundra in north‐western Finland. We measured the plots three times during growing season 2016 with a hand‐held time‐domain reflectometry sensor. To model soil moisture and its temporal variation, we used four statistical modelling methods: generalized linear models, generalized additive models, boosted regression trees, and random forests. The model fit of the soil moisture models were R2 = 0.60 and root mean square error (RMSE) 8.04 VWC% on average, while the temporal variation models showed a lower fit of R2 = 0.25 and RMSE 13.11 CV%. The predictive performances for the former were R2 = 0.47 and RMSE 9.34 VWC%, and for the latter R2 = 0.01 and RMSE 15.29 CV%. Results were similar across the modelling methods, demonstrating a consistent pattern. Soil moisture and its temporal variation showed strong heterogeneity over short distances; therefore, soil moisture modelling benefits from high‐resolution predictors, such as LiDAR based variables. In the soil moisture models, the strongest predictor was SAGA (System for Automated Geoscientific Analyses) wetness index (SWI), based on a 1 m2 digital terrain model derived from LiDAR data, which outperformed soil predictors. Thus, our study supports the use of LiDAR based SWI in explaining fine‐scale soil moisture variation. In the temporal variation models, the strongest predictor was the field‐quantified organic layer depth variable. Our results show that spatial soil moisture predictions can be based on soil and land surface properties, yet the temporal models require further investigation. Copyright © 2017 John Wiley & Sons, Ltd.

食料生産における土壌の意義 : 土耕栽培と養液栽培の比較による土壌機能の再評価(2011年つくば大会シンポジウムの概要)

食料生産における土壌の意義 : 土耕栽培と養液栽培の比較による土壌機能の再評価(2011年つくば大会シンポジウムの概要)

水土保持生态效益浅析

水土保持作为生态环境建设的重要内容，是一项实践性较强的农林水事活动。为了评价水土保持的实施效果、明确水土保持的目的与意义、对不同的水土保持方案进行比较与优选，有必要进行水土保持效益评价研究。其中生态效益在保持和改良土壤、涵养水源、固碳供氧和维持景观等方面体现重要的价值。本文通过生态效益指标体系、生态系统服务功能的水土保持效益评价和水土保持生态建设的效益评价指标体系简要说明水土保持的生态效益。 Soil and water conservation as an important part of the ecological environment construction, is a strong practice of agriculture, forestry and water activities. In order to evaluate the effect of soil and water conservation, to clear the purpose and significance of soil and water conservation, to compare and optimize the different soil and water conservation programs, it is necessary to carry out soil and water conservation benefit evaluation research, in which ecological benefits reflect the important value in maintaining and improving the soil, water conservation, carbon seques- tration and maintaining the landscape and so on. This paper briefly describes the ecological benefits of soil and water conservation through the evaluation index system of ecological benefit index system, the benefit evaluation index system of soil and water conservation ecological cons- truction and the evaluation of soil and water conservation benefit of ecosystem service theory.

The significance of soils and soil science towards realization of the United Nations Sustainable Development Goals

Abstract. In this forum paper we discuss how soil scientists can help to reach the recently adopted UN Sustainable Development Goals (SDGs) in the most effective manner. Soil science, as a land-related discipline, has important links to several of the SDGs, which are demonstrated through the functions of soils and the ecosystem services that are linked to those functions (see graphical abstract in the Supplement). We explore and discuss how soil scientists can rise to the challenge both internally, in terms of our procedures and practices, and externally, in terms of our relations with colleague scientists in other disciplines, diverse groups of stakeholders and the policy arena. To meet these goals we recommend the following steps to be taken by the soil science community as a whole: (i) embrace the UN SDGs, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030; (ii) show the specific value of soil science: research should explicitly show how using modern soil information can improve the results of inter- and transdisciplinary studies on SDGs related to food security, water scarcity, climate change, biodiversity loss and health threats; (iii) take leadership in overarching system analysis of ecosystems, as soils and soil scientists have an integrated nature and this places soil scientists in a unique position; (iii) raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services; (iv) improve the transfer of knowledge through knowledge brokers with a soil background; (v) start at the basis: educational programmes are needed at all levels, starting in primary schools, and emphasizing practical, down-to-earth examples; (vi) facilitate communication with the policy arena by framing research in terms that resonate with politicians in terms of the policy cycle or by considering drivers, pressures and responses affecting impacts of land use change; and finally (vii) all this is only possible if researchers, with soil scientists in the front lines, look over the hedge towards other disciplines, to the world at large and to the policy arena, reaching over to listen first, as a basis for genuine collaboration.

Securing our soil

Through the recognition and interplay of biochemicophysical (pedologic and edaphic), economic, social and policy dimensions, soil security is a wider and more integrative concept than previous policy- and management-focused notions such as soil conservation, soil care, soil quality, soil health and soil protection. It is the soil homolog of food, water and energy security. In this way, global significance of soil for sustainable development is emphasized. Through the five dimensions of soil security, the value of soil in addressing at least six of the current global existential challenges is formulated, and the intrinsic import of soil security as an equally essential worldwide pragmatic requirement is resolved. The immediate quest is for a multidisciplinary understanding to qualify and quantify the five dimensions effectively and efficiently so that the security of soil in fields, catchments or watersheds, regions, countries, continents and globally can be measured, maintained or improved through appropriate management and policy, and monitored on an ongoing basis.

Soil Infiltration Characteristics in Agroforestry Systems and Their Relationships with the Temporal Distribution of Rainfall on the Loess Plateau in China.

Many previous studies have shown that land use patterns are the main factors influencing soil infiltration. Thus, increasing soil infiltration and reducing runoff are crucial for soil and water conservation, especially in semi-arid environments. To explore the effects of agroforestry systems on soil infiltration and associated properties in a semi-arid area of the Loess Plateau in China, we compared three plant systems: a walnut (Juglans regia) monoculture system (JRMS), a wheat (Triticum aestivum) monoculture system (TAMS), and a walnut-wheat alley cropping system (JTACS) over a period of 11 years. Our results showed that the JTACS facilitated infiltration, and its infiltration rate temporal distribution showed a stronger relationship coupled with the rainfall temporal distribution compared with the two monoculture systems during the growing season. However, the effect of JTACS on the infiltration capacity was only significant in shallow soil layer, i.e., the 0–40 cm soil depth. Within JTACS, the speed of the wetting front’s downward movement was significantly faster than that in the two monoculture systems when the amount of rainfall and its intensity were higher. The soil infiltration rate was improved, and the two peaks of soil infiltration rate temporal distribution and the rainfall temporal distribution coupled in rainy season in the alley cropping system, which has an important significance in soil and water conservation. The results of this empirical study provide new insights into the sustainability of agroforestry, which may help farmers select rational planting patterns in this region, as well as other regions with similar climatic and environmental characteristics throughout the world.

Volume based expression of soil variables: Good descriptor of soil-plant interrelationships

This research compared the gravimetric method of expression of soil nutrient concentration with actual soil volume based expression in terms of yield response using rubber as a test crop. A rubber plantation (planted in year 1989 under a NPK fertilizer trial) was investigated. The experiment was laid out with thirteen treatments in three replications in a randomized block design planted with rubber (Clone RRII 105) at a spacing of 4.9 × 4.9 m. Twenty-four trees formed the main plot and 8 trees were used for measurements of plant related and soil parameters. The treatments included selected combinations of N, P and K; three rates of N (30, 60 and 90 kg ha-1 year-1), two rates of P (30 and 60 kg ha-1 year-1) and two rates of elemental potassium (20 and 40 kg ha-1 year-1) and a control (without fertilizer application). Urea, rock phosphate and muriate of potash were applied as source of elements, N, P and K, respectively. All the nutrients were supplied in two equal splits during April-May and September-October every year. During August 1999, soil samples were collected from all the 39 plots from a depth of 0 to 30 cm. From all these plots rubber latex yield data were also recorded simultaneously at the time of soil sampling. Results revealed that soils vary in plant exploitable actual soil volume (ASV) and its contents. However soil nutrients are not widely expressed on volume basis and gravimetric expression can be misleading when ASV is not known. Soils had different descriptive statistics of variables when expressed in both ways. No gravimetric variables were correlated with rubber yield while volumetric Ca correlated significantly (r = 0.576**). Path analysis showed that log P, log Ca, Mg, log Mn and log Fe had prominent direct effects (0.521, 0.944, 0.454, -0.595 and -0.735, respectively) and variable indirect effects through other variables. However, log Ca only yielded significant correlation with yield even after partial neutralization of direct effect with indirect effects. Path analysis revealed prominent interactions through indirect effects although some correlations (sum of direct and indirect effects) were insignificant and described 57% variability indicating the scope for inclusion of other variables to describe yield. The study provided a lead indicating the merit of volumetric expression over gravimetric expression to explore further as these observations are of practical significance in soils with spatially varied contents of coarse fragments. Key words: Actual soil volume, expression, nutrient content, path analysis, rubber latex yield.

Fungal biotransformation of zinc silicate and sulfide mineral ores

In this work, several fungi with geoactive properties, including Aspergillus niger, Beauveria caledonica and Serpula himantioides, were used to investigate their potential bioweathering effects on zinc silicate and zinc sulfide ores used in zinc extraction and smelting, to gain understanding of the roles that fungi may play in transformations of such minerals in the soil, and effects on metal mobility. Despite the recalcitrance of these minerals, new biominerals resulted from fungal interactions with both the silicate and the sulfide, largely resulting from organic acid excretion. Zinc oxalate dihydrate was formed through oxalate excretion by the test fungi and the mineral surfaces showed varying patterns of bioweathering and biomineral formation. In addition, calcium oxalate was formed from the calcium present in the mineral ore fractions, as well as calcite. Such metal immobilization may indicate that the significance of fungi in effecting metal mobilization from mineral ores such as zinc silicate and zinc sulfide is rather limited, especially if compared with bacterial sulfide leaching. Nevertheless, important bioweathering activities of fungi are confirmed which could be of local significance in soils polluted by such materials, as well as in the mycorrhizosphere.

Soil Seed Bank and Standing Vegetation of Abandoned Croplands on Chinese Loess Plateau: Implications for Restoration

Vegetation succession depends on the availability of suitable propagules in the soils, and an understanding of soil seed banks is important for effective vegetation restoration of abandoned croplands. Aims of this study were to identify characteristics of soil seed bank, relationship with standing vegetation, and potential significance of soil seed bank for vegetation restoration in abandoned croplands on the hilly-gullied Loess Plateau. Results of field survey, germination, and correspondence analysis showed that density of soil seed bank ranged from almost 900 through almost 6470 seeds m−2 at 0–5 cm depth and almost 120 through almost 2470 seeds m−2 at 5–10 cm depth, with species richness of 7–14. Early successional species dominated soil seed bank, while later successional species occurred only at low densities. Similarity between soil seed bank and standing vegetation was low (with an average of 0.261). Most important variables contributing to the variation of the standing vegetaion included soil water, extractable P, soil seed bank density, and aspect. Soil seed bank alone explained 32% of vegetation community variation. Potential for vegetation restoration from soil seed banks is limited, and it is recommended to transplant some later successional species into abandoned croplands to accelerate succession.

Significance of Wettability‐Induced Changes in Microscopic Water Distribution for Soil Organic Matter Decomposition

The significance of soil water‐repellent properties has been discussed with respect to water dynamics and distribution; however, there are indications of their importance also for C stabilization processes. Water‐repellent aggregates, for example, have been shown to protect soil organic matter (SOM) due to their stability against water slaking. Soil wettability can act as a key factor for SOM decomposition as it controls the microbial availability of water and nutrients. The main objective of this study was therefore to investigate the impact of wettability on C release by linking the wetting properties in terms of the contact angle to soil respiration parameters. For this, the wetting properties of two topsoil samples (an Orthic Luvisol and a Dystric Cambisol) were altered by the addition of particles that were hydrophobized by treatment with dichlorodimethylsilane (DCDMS). Additionally, aggregates were created to assess whether artificial aggregation also can contribute to SOM protection. Environmental scanning electron microscopy revealed a locally confined distribution of water for the DCDMS‐treated material, compared with untreated soil where water was uniformly distributed. Measurements indicated an increasing contact angle with increasing amount of DCDMS‐treated particles in the mixtures. With increasing contact angle, C release decreased, suggesting that wettability‐induced changes in water distribution can significantly affect the decomposition of SOM. Respiration from artificial aggregates, however, was not reduced compared with the corresponding homogeneous material. We conclude that wettability is an important factor for SOM decomposition as it governs the spatial distribution and availability of water necessary for microbial activity.