Soil Color Research Articles

Quantitative relationships between Munsell colour attributes and organic carbon in highly weathered tropical soils

Soil organic carbon (SOC) is a very important parameter for assessing the quality of agricultural soils. However, the availability and use of such data by resource-poor farmers, especially in Sub-Saharan Africa, remains a major challenge due to the financial and time constrains involved. Thus, there is need to assess and adopt reliable methods for the rapid estimation of soil organic carbon content by indigenous farmers and field users. The objective of this study was to evaluate the quantitative relationships between soil organic carbon and Munsell colour attributes (value and chroma) in highly weathered tropical soils of the Northwestern Highlands of Cameroon. Forty-six soil profiles (28 Acrisols and 18 Ferralsols), including 46 surface (A) horizons and 181 subsurface horizons (Bo, Bt) were used. Soil organic carbon data and Munsell colour attributes, obtained through standard procedures, were subjected to descriptive statistical, correlation, regression and principal components analyses, in order to evaluate the relationships existing between SOC and Munsell colour attributes. In general, there were negative and significant (p < 0.001) correlations between SOC and all Munsell colour attributes (chroma, value, value + chroma, and value +0.5 chroma). The best models relating SOC and Munsell colour attributes were logarithmic models, with soil colour explaining >70 % of the variance. The results indicate that SOC in highly weathered tropical soils can be conveniently estimated using Munsell soil colour attributes (value + chroma). Better estimates were obtained using logarithmic models for surface (A horizon) soil samples having a sand content >50 %.

The Seismic Surface Rupture Zone in the Western Segment of the Northern Margin Fault of the Hami Basin and Its Causal Interpretation, Eastern Tianshan

The Eastern Tianshan region, influenced by the far-field effect of northward compression and expansion of the Qinghai-Xizang block, features highly developed Late Quaternary active faults that exhibit significant neotectonic activity. Historically, the Barkol-Yiwu Basin, located to the north of the Eastern Tianshan, experienced two major earthquakes in 1842 and 1914, each with a magnitude of M71/2. In contrast, the Hami Basin on the southern margin of the Eastern Tianshan has no historical records of any major earthquakes, and its seismic potential, mechanisms, and future earthquake hazards remain unclear. Based on satellite image interpretation and field surveys, this study identified a relatively recent and well-preserved seismic surface rupture zone with good continuity in the Liushugou area of the western segment of the Northern Margin Fault of the Hami Basin (HMNF), which is the seismogenic structure responsible for the rupture. The surface rupture zone originates at Kekejin in the east, extends intermittently westward through Daipuseke Bulake and Liushugou, and terminates at Wuzun Bulake, with a total length of approximately 21 km. The rupture zone traverses the youngest geomorphic surface units, such as river beds or floodplains and first-order terraces (platforms), and is characterized by a series of single or multiple reverse fault scarps. The morphology of fault scarps is clear, presenting a light soil color with heights ranging from 0.15 m to 2.13 m and an average displacement of 0.56 m, suggesting that this surface rupture zone likely represents the most recent seismic event. Comparison with historical earthquake records in the Eastern Tianshan region suggests that the rupture zone may have been formed simultaneously with the Xiongkuer rupture zone by the 1842 M71/2 earthquake along the boundary faults on both sides of the Barkol Mountains, exhibiting a flower-like structural pattern. Alternatively, it might represent a separate, unrecorded seismic event occurring shortly after the 1842 earthquake. The estimated magnitude of the associated earthquake is about 6.6~6.9. Given that surface-rupturing earthquakes have already occurred in the western segment, the study indicates that the Erdaogou–Nanshankou section of the HMNF has surpassed the average recurrence interval for major earthquakes, indicating a potential future earthquake hazard.

Comparing soil colour using colour chart and colour app: A semi-quantitative approach with data transformation Using pedometric methods

Comparing soil colour using colour chart and colour app: A semi-quantitative approach with data transformation Using pedometric methods

Characterization of soil organic carbon at profile scale in two forest soils under pine and holm oak

Context It is essential to promote soil carbon sequestration as a means to mitigate climate change. Thus, it is fundamental to know the distribution of C in the soil at profile scale, the characteristics of humic substances as indicators of soil organic matter (SOM) turnover and their relationship with other soil properties. Aims Two forest ecosystems under pine and holm oak developed under a Meso-Mediterranean climate in Spain were used to characterize SOM through the complete sequence of layers of the soil profile. Methods General soil analysis, infrared spectroscopic analysis and soil color measurements were conducted for the characterization. Key results Humus form under oak was found to be Mull mesotrophic–Mull acid while humus under pine Moder oligotrophic. The infrared spectrum determined that oxidation of the humic acids was more complete in the deeper horizons. Relationships between intensities of the main spectral bands in both soils followed similar maximum and minimum sequence values. The total humic extract (THE) color measured by reflection was found inversely related to the THE color measured by transmission. In the same way, the color spectrum between 350 and 800 nm in the THE showed an inverse relation between hue/brightness and absorbance values. Conclusions Infrared analysis and color measurements provided evidence of a different level of stabilization of humic substances from each soil, and between the different horizons. Large spatial variability in soil organic carbon quantity and quality was observed. Implications Better understanding of carbon sequestration behavior in different soil ecosystems in its crucial role within the global carbon cycle

Soil Physical Properties of Oil Palm Plantations in Tidal Areas of Peatland

Oil palm (Elaeis guineensis Jacq) is a plant with a higher vegetable oil content than other oil-producing plants, so palm oil is widely used as the main raw material for processed vegetable oil. The increasingly limited land area and the larger land area in Indonesia so that the space for plantation companies to expand the land is increasingly limited, so that the expansion of oil palm plantations began to change from optimal land to suboptimal land. Soil physical properties are properties related to the shape or original condition of the soil. This study aims to determine the physical properties of soil (texture, porosity, moisture content, soil color, particle density, and bulk density) on peatlands in the tidal area of PT Sinar Gunung Sawit Raya. This research used survey method with descriptive analysis. The soil samples taken were peat soil in the tidal area with purposive random sampling method at a depth of 30 cm. This research was conducted in November 2023 and continued in the laboratory for testing each soil physical properties. The results of the research on soil physical properties at PT Sinar Gunung Sawit Raya on peatlands in tidal areas show that the soil texture is loamy sand, soil porosity is good, moisture content is relatively normal, soil color looks relatively dark, particle density is still low and bulk density value shows low. Keywords: Loamy sand, Oil palm, Peat soil, Soil color, Soil texture.

Biofertilizers: A sustainable strategy for enhancing physical, chemical, and biological properties of soil

A biofertilizer is a biologically derived substance that can enhance soil fertility. It is beneficial for enhancing soil fertility by introducing microorganisms that produce organic nutrients and perhaps decreasing plant illnesses. An extensive review was done to examine the efficacy of several biofertilizers in improving soil properties, including their physical, chemical, and biological characteristics. The secondary data and material for the article were gathered from a variety of sources, including government reports, published research papers, reports from various organizations, and pertinent websites that were examined and their conclusions presented. Although biofertilizers have proven to be a very sustainable method for improving soil quality and increasing crop output, there is a lack of extensive research on their effects on soil’s physical, chemical, and biological aspects. This study aims to offer a comprehensive understanding of various biofertilizers and their effects. This investigation indicated that biofertilizers such as Nitrogen-fixing bacteria, phosphate solubilizers, and potassium solubilizers help to increase NPK content in the soil leading to an increase in the productivity of soil. Moreover, biofertilizers help to enhance soil physical properties (soil bulk density, soil moisture, soil temperature, and soil color), chemical properties (soil pH, soil nitrogen content, soil phosphorus content, soil potassium content, and soil organic carbon content), and chemical properties (population of bacteria, fungi, and actinomycetes). Overall, by overcoming the challenges with biofertilizers in agriculture, we can attain agricultural sustainability.

Effect of In Situ Polymerization of Super Absorbent Polymers on the Protection of Earthen Heritage Sites in Semi-Arid Regions

As precious cultural heritage, earthen sites are susceptible to various natural factors, leading to diverse forms of degradation. To protect earthen sites, the effects of super absorbent polymers (SAPs) on soil water retention, physical properties, and color compatibility at different concentrations were studied. After applying SAP treatment to an earthen site with different degrees of weathering, we drew the following conclusions. SAP-2 improved soil water retention capacity, increased soil water content, and slowed down the precipitation of soluble salts. At the same time, SAP-2 had the least effect on soil color difference and reduced the development of cracks by filling soil pores and enhancing the cohesion between soil particles, thus giving the earthen sites better weathering resistance. Therefore, the results provide a useful reference for the surface cracking of earthen sites in semi-arid areas and the degradation caused by flaking and block spalling.

Characterization and Classifications of Saline/Sodic Soils of Ambo Area of Irrigated Farm Land in Golina Watershed in Raya Valley, Amhara Region, Ethiopia

All soils are known to contain a certain amount of soluble salts and exchangeable sodium, magnesium, potassium, and calcium. However, excessive enrichment of any one of them can interfere with many soil processes, including plant growth, and the effects depend on the degree of enrichment and the type of plant. Therefore, the objective of this study was to characterize the salt-affected soils of the Ambo area for irrigated farmlands in the Golina Watershed in Raya Kobo Woreda, Amhara region. One profile was excavated from an irrigated field to carry out this activity. One profile was excavated from the irrigated field to conduct this activity. Ten soil samples were taken from the soil profile at 2 m depth at 20 cm depth intervals. The samples were analyzed for several soil physical properties, including soil pH, soluble cations and anions, soluble salts (electrical conductivity, EC), exchangeable cations (Ca, Mg, Na, K), total nitrogen, organic carbon, soluble phosphorus, percent exchangeable sodium, sodium absorption, and soil physical properties (soil color, texture, bulk density, and soil porosity). Chemical properties were also analyzed. The analysis showed that the irrigated farmland soils had a pH of 7.6 to 8.8, electrical conductivity of 1.3 to 14 dsm-1, organic carbon of 0.3 to 1.2%, total nitrogen of 0.11 to 0.35%, soluble phosphorus of 24 to 41.4 mg kg-1, and cation exchange capacity of 50.3 to 65.5 cmol(+) kg-1. The distribution of exchangeable calcium was not consistent across the soil profiles of the irrigated farmlands. In general, the top layer of soil at both sites (because of its agricultural use) was considered for EC, ESP, and pH values. The irrigated farmland soils were classified as saline soils.

Effects of Agricultural Land Use on Desert Soil Classification in Holy Karbala Governorate

This study was conducted to evaluate physical, chemical, and morphological features to classify soils at the subgroup level. The research area, located west of Karbala, consists of three locations, each comprising pedons in both cultivated and uncultivated lands. GPS coordinates were recorded, and morphological descriptions of pedon horizons were made in accordance with the American Soil Survey Manual. This study investigates the effect of agricultural land use on the classification of desert soils in the Holy Karbala Governorate. The results revealed that the dry climate caused diversity in the morphological features of the soils, mainly in horizon type, thickness, and arrangement. Agricultural usage had an impact on diagnostic horizons, particularly the gypsic horizon, and features such as soil color, structure, organic matter, carbonate minerals, gypsum, and root distribution. However, there was no substantial impact on soil texture development, and soils did not show a consistent pattern of soil separation distribution with depth, indicating weak pedogenic processes. The most common texture classes were loamy sand, sandy loam, and sand, with sand contents ranged from 902.08 to 574.12 g kg. Soil bulk density differed from 1.67 to 1.30 Mg m³, with lower values in farmed areas. Chemical properties were influenced, with soil pH ranging from 8.36 to 7.54, electrical conductivity (EC) from 5.46 to 2.03 dS m, cation exchange capacity (CEC) from 15.25 to 2.05 meq.100g, organic matter from 43.51 to 1.18 g kg, carbonate minerals from 461.18 to 174.06 g kg, and calcium sulfate from 182 to 21 g kg. The soils were classed as Aridisols because they were found in a dry desert with an Aridic moisture regime. The presence of distinctive saline layers such as Calcic and Gypsic was discovered, resulting in the classification of cultivated soils as Typic Haplocalcids and uncultivated lands as Typic Calcigypsids.

Attributes and Fertility Ranking of Lade Soils in the Southern Guinea Savanna of Nigeria

A major constraint restraining agricultural production in Nigeria is the scarcity of gen on soil property. The concomitant improper land use results in land degradation and dwindled agrarian efficiency. Consequently, this study seeks to assess the physicochemical attributes and classify and rank Lade soils according to fertility potential. The free survey was conducted to collect representative soil data. Six (6) profile pits designated L1 to L6 were dug to characterize the mapping units using soil samples obtained from horizons in respective profiles for the study of physical and chemical characteristics employing standard laboratory techniques. Profile description and soil classification at the Great Group level followed USDA guidelines. Fertility Capability Classification system was used to evaluate the soils for arable cropping. Soil was indicative of a relatively high structural index (&gt;9%), strong to slightly acidic (4.0 – 6.3). Organic carbon (8.02 – 9.24 g kg -1 ), available P (9.66 – 25.76 mg kg -1 ) and total N (0.09 – 0.34 g kg -1 ) were mostly moderate. Extractable bases ranged from high to very high while soil color diverse from dark yellowish brown (10YR 4/4) on the surface to reddish brown (2.5YR 4/3) in the subsoils. Soils L1 - L6 were classified as Endoaqualfs, Kandiustalfs, Haplustalfs, Haplustalfs, Plinthustalfs and Kandiustalfs, respectively. Potential suitability for arable crop place pedons L1 and L3 in class S2 (moderately suitable), whereas other pedons were rated as S3 (marginally suitable). The study gives an insight into the judicious use of inorganic fertilizer combined with good residue management and drainage for fertility improvement of the soil. Keywords : Characterization, Fertility capability classification, nutrient status, sandstone, soil taxonomy

Pedogenic variables with color indices of rubified Alfisols in the Kakalachinte microwatershed, Karnataka, South India

Soil properties and processes can often be estimated by soil color, which provides valuable information about composition and other properties. We focused on the morphology, particle size distribution, and chemical properties of Alfisols in Kakalachinte microwatershed, Karnataka, India. Soil redness indices were calculated: Buntley's and Westin's rate (BWR), Hurst's rate (HR); Torrent’ rates (TR1 and TR2); Barrón's and Torrent's rates (BTR1 and BTR2), and Viscarra's rate (VR). The Munsell notation was converted to the CIE (Commission Internationale del'Eclairage, CIE) Lab system, Lab model: L*, luminance, a*, redness, and b*, yellowness of moist soil samples. Forty-five soil samples were characterized for texture, soil reaction (pH), electrical conductivity, calcium carbonate content, organic carbon (OC) content, exchangeable cations (sodium, Na; potassium, K; magnesium, Mg; and calcium, Ca), base saturation (BS), and cation exchange capacity (CEC). The pH of the soils ranged from strongly acid (pH of 5.25) to strongly alkaline (pH of 8.73). These soils exhibited low CEC, with a mean of 8.36 cmol(+)/kg and a coefficient of variation of >35%. The BS was found to be >70%, with a dominance of exchangeable Ca (6.93 ± 1.08 cmol(+)/kg). Correlation analysis revealed strong positive relationships between OC and the L* value (r = 0.6**). The correlation results revealed a strong positive correlation of a* value with TR1 (r = 0.54**), significant negative relationship between L* and BTR1 (r = −0.54*), BTR2 (r = −0.525*), and VR (r = −0.53*). Regression between soil OC and the L* value showed R2 of 0.40 and RMSE of 0.01; soil exchangeable K and Mg with the R2 = 0.74; RMSE = 0.12 and the R2 = 0.42; RMSE = 0.11 at p < 0.001. The study highlights the importance of converting Munsell color notation to the CIELab system for understanding the rubification process in relation to soil properties in Alfisols at the microwatershed level.

Assessment of Physico-Chemical Properties of Soil from Different Blocks of Eluru District, Andhra Pradesh, India

The experiment was conducted in 2023 to assess the physical and chemical properties of different blocks of Eluru district, Andhra Pradesh. Three distinct villages were chosen from each block for the study. The physical properties of Eluru district soils, soil colour, texture, bulk density(mg m-3), particle density (mg m-3), percent pore space and percent water retaining capacity and chemical properties pH, EC (dSm-1 ) at 25˚C, percent organic carbon, available nitrogen, phosphorus and potassium (kg ha-1), calcium C mol (p+) kg-1 and magnesium C mol(p+) kg at 0-15, 15-30 and 30-45 cm depth. Findings showed that in terms of depth, there was a minor rise in both bulk and particle density. The water retaining capacity of the soil and the overall physical condition of the soil was found good and supportive for plant growth. The soils of selected villages of different blocks in Eluru district were found to acidic to basic in nature due to soil minerals producing sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) upon weathering. The organic carbon, nitrogen and phosphorus were observed as medium to high. The potassium content was low in all locations. There was enough calcium present, however there were several regions where magnesium was lacking. The deficiency of the nutrients can be mitigated by the use of organic and inorganic fertilizers.

Assessment of Physico-Chemical Properties of Tea Garden Soils of Darjeeling, West Bengal, India

The experiment was conducted in 2023-2024 to assess the physical and chemical properties of tea garden soils of Darjeeling, West Bengal within its geographical coordinates ranging from 27° 2' 9.6252'' N latitude to 88° 15' 45.6192''E longitude. Nine distinct villages located in the Darjeeling district covering Glenburn, Soureni, and Selimbong tea gardens were chosen for the study. The physical properties of tea garden soils, soil colour, texture, bulk density (Mg m-3), particle density (Mg m-3), percent pore space and percent water holding capacity were analysed at 0-15, 15-30 and 30-45 cm depths. The results showed that the soil colour varied from brown to yellowish brown in dry condition and dark brown to dark reddish brown in wet. The soils of Selimbong were sandy loam to sandy clay loam, Soureni were clay loam, and soils of Glenburn were clay loam to sandy clay loam in texture. The variation in bulk density and particle density was recorded non-significant with the values ranging from 1.01-1.22 Mg m-3 and 2.21-2.64 Mg m-3 respectively. The percent pore space and percent water holding capacity were found significant with the values ranging from 50.53-68.96% and 53.36-79.43% respectively. The soil pH ranged from 4.32-5.28 and electrical conductivity (EC) 0.03-0.97 dS m-1 which were found to be non-significant. The organic carbon and available nitrogen were found to be significant with values ranging from 0.63-2.02% and 177.70-696.3 kg ha-1 respectively. The available phosphorus ranged from 16.13-29.54 kg ha-1 and available potassium 100.64-334.92 kg ha-1 which was found to be significant. The values of exchangeable calcium and magnesium were recorded significant ranging from 0.02-0.42 C mol(p+) kg-1 and 0.016-0.223 C mol(p+) kg-1 respectively.

The assessment of soil organic matter in the KwaZulu-natal province of South Africa and its relationship to spectroscopy data

Soil organic matter (SOM) is made up of decomposing biotic material in various stages, as well as compounds generated by plant roots and soil organisms—it helps the soil’s biophysical functions. Laboratory spectroscopy, for example, provides a novel technique to analyse SOM content because it is both cost and time-efficient. Because of its composition and biophysical features, SOM has a distinct spectral reflectance; this relationship has been effectively exploited to estimate and predict SOM. The purpose of this study is to investigate the link between SOM concentration and laboratory-based soil spectral reflectance in the Emakhosaneni subplace of uThukela District, KwaZulu-Natal, South Africa. We collected 13 random soil samples from each of the four major land use types (agricultural, residential, eroded land, and rangeland), totalling 52 samples. To assess the SOM content, we oven-dried the materials overnight (105 °C), crushed them, sieved them (1 mm), and analysed them using the Walkley-Black method. The spectral reflectance of the soil samples was then acquired using the Analytical Spectral Device (ASD) FieldSpec3 and pre-processed for noise reduction before analysis. We found that the area’s average SOM content was 2.19%, with agricultural land having the greatest average SOM content (2.98%), followed by rangeland (2.46%), residential (1.77%), and eroded land area (1.56%). However, the average reflectance of the spectra was higher on eroded areas and decreased to a minimum on agricultural areas. This is attributed to the relationship between soil colour and SOM. Correlation analysis demonstrated a moderately negative relationship between SOM concentration and spectral reflectance over the whole spectral range covered (400–2400 nm). Our partial least squares regression analysis revealed that pre-processed spectra data models (FDT; R2 = 0.46 and SG; R2 = 0.34) performed better than raw data models, in both calibration and validation data sets, respectively. Despite the influence of noise on raw data model performance, they modestly predicted SOM content, particularly on the validation data set. However, the developed model cannot be used due to the very low coefficient of determination. Our results highlight the importance of spectroscopy to assess SOM content, and further research can be carried out on a larger scale.

Assessment of Physico-chemical Properties of Soil from Various Regions of Different Taluk of Pathanamthitta District in the State of Kerala, India

The assessment of Physico-Chemical Properties of Soil from Various Regions of Different Taluk of Pathanamthitta District of Kerala in 2023-24 was a valuable endeavour. A total of 27 samples were collected at profile depths of 0-15, 15-30, and 30-45. It is interesting to note the variations in soil colour between dry and wet conditions, ranging from light brown to dark reddish brown.The soil textural class was identified as Sandy clay Loam, and the sand, silt and clay percentage varied from 45.18% to 50.64%, 17.21% to 20.70%, 30.91% to 34.61%. Bulk Density was varied from 1.08 Mg m-3 to 1.28 Mg m-3. The Particle Density varied from 2.02 Mg m-3 to 2.55 Mg m-3. The Pore Space (%) ranged from 40.18% to 50.62%. The Water Retaining Capacity (%) ranged from 39.19 to 48.98%. The pH value ranged from 4.9 to 6.9. The Electrical Conductivity ranged from 0.03 to 0.30 dS m-1. The value of total Organic Carbon (%) varied from 0.16 to 1.68 %. The available Nitrogen content of soil ranged from 119.45 to 286.07 kg ha-1. The available Phosphorus content of soil ranged from 13.23 to 64.20 kg ha-1. Available Potassium content of soil ranged from 100.80 to 382.40 kg ha-1. Exchangeable Calcium content of soil ranged from 1.7(meq 100g-1) to 9.1(meq 100g-1). Exchangeable Magnesium content of soil ranged from 0.23 (meq 100g-1) to 0.74(meq 100g-1). The Sulphur content of soil ranged from 0.03 to 0.44 kg ha-1. The findings revealed minor increases in bulk and particle density with depth, yet the overall physical condition of the soil seems favourable for plant growth. It is evident that the soils are slightly acidic but meet the acceptable EC limit. The high levels of Organic Carbon are promising, while Nitrogen is lower and Phosphorus and Potassium levels are moderate to high. However, secondary nutrients like Calcium, Magnesium, and Sulphur are relatively low. Nutrient levels appear to be influenced by soil depth, with leaching due to higher precipitation levels in the area contributing to nutrient deficiencies. The results suggest that improvements can be made by implementing strategies such as cover crops, green manure, legume cultivation, mulching, and specific cropping systems to address leaching concerns.

Automatic Irrigation System Based on Computer Vision and an Artificial Intelligence Technique Using Raspberry Pi

Efficient irrigation water use directly affects crop productivity as demand increases for various agricultural products due to population growth worldwide. While technologies are being developed in various fields, it has become desirable to develop automatic irrigation systems to reduce the waste of water caused by traditional irrigation processes. This paper presents a novel approach to an automated irrigation system based on a non-contact computer vision system to enhance the irrigation process and reduce the need for human intervention. The proposed system is based on a stand-alone Raspberry Pi camera imaging system mounted at an agricultural research facility which monitors changes in soil color by capturing images sequentially and processing captured images with no involvement from the facility’s staff. Two types of soil samples (sand soil and peat moss soil) were utilized in this study under three different scenarios, including dusty, sunny, and cloudy conditions of wet soil and dry soil, to take control of irrigation decisions. A relay, pump, and power bank were used to achieve the stability of the power source and supply it with regular power to avoid the interruption of electricity.

Assessing the utility of Munsell soil color in building and evaluating spectral models for soil clay content prediction

AbstractThe present study examined how the use of soil color can help build and evaluate clay content prediction models from laboratory visible and near infrared spectroscopic data. This study was based on a regional database containing 449 soil samples collected over Karnataka state in India, which has been divided into red soils (240 samples) and black soils (209 samples) based on their Munsell soil color. Partial least squares regression models were calibrated and validated from both the regional datasets and subsets stratified as red and black soils. In addition, a random forest model was used to classify the validation soil samples into black and red classes to evaluate models’ performance. First, while the clay content predicted by the regression model built from regional data was evaluated as correct at regional scale (R2val of 0.75), this model was evaluated as more accurate over black (R2val of 0.8) than red (R2val of 0.63) soil samples. Second, the regression models built from subsets stratified per soil color provided different performances than the regression model built from the regional data, both at the regional scale and soil color scale. In conclusion, this study demonstrated that (1) predictions are highly dependent on calibration data, (2) the interpretation of prediction performances relies heavily on validation data, and (3) pedological knowledge, such as soil color, can be effectively employed as an encouraging covariate in both the construction and evaluation of regression models.

Soil organic carbon and nutrient characteristics of Anogeissus groves in old Opara forest reserve, Nigeria.

Forest-savanna transition zones of West Africa are uniquely characterized by forest groves, forest patches, or forest islands, the importance of which for sustainable resource management and their potential for carbon sequestration and nutrient cycling is often underrated. Our study conducted a comparative analysis of the soil organic carbon and nutrient characteristics of the Anogeissus groves in the old Opara forest reserve and their adjoining arable lands. We established 30 sampling frames of 100m × 100m plots with 15 frames per land use type. For each sampling frame, six observation points were randomly selected, and composite soil samples were collected at soil depths of 0-20cm and 20-50cm per observation point. Our results showed Anogeissus groves and their adjoining arable lands to exist on similar landscapes while the groves have enriched soil morphological characteristics (e.g., soil color), higher soil organic carbon (SOC), and better nutrient characteristics. There were strong positive relationships between SOC, effective cation exchange capacity, total nitrogen, calcium, magnesium and calcium, zinc, electrical conductivity, and copper. The significant soil organic matter accumulation in the groves accounts for the overall improved soil characteristics over the adjoining arable lands. Preserving the groves and similar Africanecosystems may be important in climate regulation, resources and biodiversity conservation, and ethnopharmacology for rural communities. Thus, a question arises: should more land be set aside for ecological conservation or for agricultural productivity?

Pedological features of a sustainable halophyte wetland: El Hito saline pond (Central Spain)

AbstractIn semi‐arid Mediterranean regions, particularly in some wetland soils, salinity is thought to be an indicator of low‐quality soils. In this study, a characterization is presented of the soils surrounding El Hito saline pond (Castilla La Mancha, Central Spain), an ecological halophyte niche within a natural semi‐arid steppe land. The main aim is to classify the salt‐affected soils and their morphology, genesis, and physico‐chemical properties. Four soil profiles were opened with a backhoe machine for sampling and subsequent description on the basis of their pedogenetic morphology. Systematic surface sampling was also performed. Standard methods were followed to measure the soil properties of 27 samples. Overall electrical conductivity (EC) and pH levels of the wetland were mapped (using ArcGIS 3.1.3). Soil salinity at elevated levels was detected, inhibiting plant uptake of water and nutrients. Distinct sub‐areas of extreme elevated surface salinity providing specialized plant habitats and poor soil structure were observed, as well as a mainly whitened‐yellowish‐greenish soil colour due to salt accumulation and poor drainage. The soils also showed alkaline pH values. In most samples, the pH was over 8.5, and EC was higher than 4 (dS m−1), and in several samples higher than 20 (dS m−1). A low sodium (Na) content was detected in the saturation extract where magnesium (Mg+) was the dominant soluble cation, followed by both calcium (Ca+) and sodium (Na+), and then potassium (K+), present in lower proportions. Sulphate (SO42−) and then chloride (Cl−) anions were dominant, although carbon trioxide, (CO3−) and carbonate (CO32−) anions were also present. The percentages of organic carbon (C) were very low, while total nitrogen (TN) and available phosphorus (P) were higher in the upper horizons, suggesting a degree of eutrophication. The present work will increase the existing knowledge about the role of El Hito saline pond, that play a vital ecological role in the broader biosphere, providing new suggestions to readers on how this knowledge can be used to improve these types of ecosystems. In particular, the agricultural pesticides and fertilizers continuously damage the soil fertility as evidenced by the high content of soluble phosphorus found in some points of the Hito saline pond.

High-Throughput Phenotyping for the Evaluation of Agronomic Potential and Root Quality in Tropical Carrot Using RGB Sensors

The objective of this study was to verify the genetic dissimilarity and validate image phenotyping using RGB (red, green, and blue) sensors in tropical carrot germplasms. The experiment was conducted in the city of Carandaí-MG, Brazil, using 57 tropical carrot entries from Seminis and three commercial entries. The entries were evaluated agronomically and two flights with Remotely Piloted Aircraft (RPA) were conducted. Clustering was performed to validate the existence of genetic variability among the entries using an artificial neural network to produce a Kohonen’s self-organizing map. The genotype–ideotype distance index was used to verify the best entries. Genetic variability among the tropical carrot entries was evidenced by the formation of six groups. The Brightness Index (BI), Primary Colors Hue Index (HI), Overall Hue Index (HUE), Normalized Green Red Difference Index (NGRDI), Soil Color Index (SCI), and Visible Atmospherically Resistant Index (VARI), as well as the calculated areas of marketable, unmarketable, and total roots, were correlated with agronomic characters, including leaf blight severity and root yield. This indicates that tropical carrot materials can be indirectly evaluated via remote sensing. Ten entries were selected using the genotype–ideotype distance (2, 15, 16, 22, 34, 37, 39, 51, 52, and 53), confirming the superiority of the entries.