Major Soil Types Research Articles

Vertical Transport of HDPE Microplastics through Sandy and Silty Soil

Microplastic pollution is an emerging concern and poses a potential risk to soil ecosystems and subsequently can lead to groundwater contamination. The sandy and silty soils are the major soil types covering more than 31 % of the land area globally. The vertical transport of microplastic in sandy and silty soil and further possible groundwater contamination is still unclear and not fully understood in the literature. The present study focuses on the movement of High-Density Polyethylene (HDPE) microplastics in quartz sand and silty soil using column experiments. Detailed flow through laboratory experiments are performed to understand the effect of varying the critical parameters in contaminant transport such as pore volumes (1PV,2PV,3PV,4PV,5PV,6PV,7PV,8PV,9PV,10PV) and flow rates (20,40,60,80,100,120 ml/min) on HDPE microplastic movement in sandy and silty soil separately. The maximum depth of microplastic transport in sandy soil was 20-22 cm for a flow rate of 120 ml/min, and 10-12 cm for 20 ml/min. In silty soil, the maximum depth of microplastic transport was 12-14 cm for 120 ml/min and 6-8 cm for 20 ml/min. The study also estimates the number of years required for microplastic contamination to reach groundwater under field conditions by considering the L/S ratio. The study estimated that it could take 144 years for microplastics to penetrate sandy soil and 356 years for silty soil, under the study conditions. The study highlights the significant threat posed by microplastics to groundwater contamination. The results suggest that soils may serve as both a sink for microplastics and a potential pathway for their entry into subsurface environments, such as underground habitats and water sources.

Cocoa pod husk-derived organic soil amendments differentially affect soil fertility, nutrient leaching, and greenhouse gas emissions in cocoa soils

The depletion of soil nutrients and decline in yields on cocoa farms in west Africa over time force farmers to abandon their farms and look for new fertile land, thereby contributing to deforestation. Cocoa pod husks (CPH) are a major farm waste representing considerable export of nutrients from cocoa soils, particularly P and K. Here, the impacts of soil amendment with raw CPH residues, CPH compost, CPH biochar, or a CPH compost-biochar mixture on soil fertility, greenhouse gas (GHG) emissions, and nutrient losses via leaching were assessed in two laboratory experiments using two major soil types used for cocoa cultivation in Ghana (an acidic Ferralsol and an alkaline Nitisol). In Experiment 1, soil nutrient availability and CO2 and N2O emissions were quantified, whereas simulation and quantification of nutrient leaching were conducted in Experiment 2. Soil pH increased from 4.8 and 8.6 by 1.4- and 1.1-folds on average in amended Ferralsols and Nitisols, respectively. Soil electrical conductivity increased in soils amended with CPH compost and/or biochar. Addition of raw CPH caused remarkable microbial immobilisation of N and reduced N availability and leaching, whereas CPH compost and/or biochar addition increased soil nitrate availability but reduced soil ammonium availability. Leaching of Ca in Nitisols was reduced when CPH biochar was included in the soil amendment. While soil K availability increased in all amended soils, most notably when CPH biochar was included, soil P and Ca availabilities were greatest where CPH compost was included. Soil total GHG emission (CO2 plus N2O) increased in all amended Ferralsols and the Nitisols amended with CPH compost or raw CPH, with the latter remarkably increasing soil CO2 emission by up to 14.8-folds. Compared to sole CPH compost amendment, CPH compost-biochar mixture amendment reduced soil total GHG emission and N and P leaching. These findings show that composted and/or pyrolysed CPH can be judiciously used to enhance soil fertility in cocoa farms, particularly in acidic soils. Pyrolysed CPH is especially beneficial for reducing soil nutrient leaching and GHG emissions and thus for increasing the sustainability of cocoa production in Ghana and west Africa.

Impact of Contrasting Rates of Phosphate Fertiliser Addition in Two Vertisols: Effects of Fresh Application and Residual Fertiliser on Sorption and Plant Uptake

Cropping systems in many sub-tropical and tropical regions rely on phosphorus (P) fertilisers to maintain crop yields. However, crop responses are often spatially and temporally inconsistent. This study evaluated P availability from dispersed applications of fresh phosphate fertiliser and their residual effect in two contrasting Vertisols - a major soil type for crop production. We collected soils that had received mono-ammonium phosphate (MAP) fertiliser four years prior to sampling (residual), as well as unfertilised soils to which we applied MAP at equivalent rates (‘fresh’). Soil P tests quantified the potential P availability arising from the residual and fresh P applications, and P sorption curves were generated to describe the P sorption/desorption dynamics. A 45-day pot trial evaluated wheat growth and P uptake from fresh and residual P applications in both soils. Soil tests and sorption curves reflected differences in P addition in the two soils, although the sorption characteristics did not differ appreciably in response to residual P. Crop growth and P uptake strongly increased with increasing P availability, with greater responses for the freshly applied P. Low P recovery from aged fertiliser applications demonstrated that the availability of residual P for crop uptake after dispersed applications is limited in Vertisols. P-tests and sorption measurements could collectively capture potential soil P reactions and plant P availability in two contrasting Vertisols. Residual P benefits from dispersed applications remained low. Enrichment in a defined soil volume (i.e., banding) merits further investigation in this soil type.

Evaluating different green manuring plant species and stool destruction methods for enhancing sugarcane yield at Wonji-Shoa Sugar Estate, Ethiopia

The long-term intensive production system employed in the Sugar Estates in Ethiopia, characterized by monoculture, preharvest burning, and excessive tillage, has led to soil degradation with a concomitant decline in sugarcane yield. Therefore, a study was conducted at Wonji-Shoa Sugar Estate (WSSE) with the objective of evaluating the effectiveness of different green manuring plant species and cane stool destruction methods (SDMs) in improving cane yield. To that end, seven green manure plant species (sunn-hemp, lablab, cowpea, soybean, mungbean, dhaincha, and sugarcane trash) were evaluated under three SDMs (cultivating-out, spraying-out with herbicide, and maintaining the stool as it is) using a split-plot design. The experimental fields were established on two major soil types, with green manure crops incorporated into the soil before planting the sugarcane. The dry matter production and nitrogen contribution of the green manure plants, as well as the height, population, diameter, and yields of sugarcane, were determined and subsequently subjected to statistical and economic analysis. The results showed that cowpea, followed by lablab, dhaincha, and sunn hemp, were the most effective green manures in terms of improving cane performance, with up to 17–20 % yield advantage and 21–40 % net economic benefits over the control treatment. Additionally, the spraying-out MSD was as effective as the cultivating-out MSD, but both outperformed maintaining the stool. In conclusion, utilizing these green manuring crops in combination with the spraying-out SDM presents notable advantages for improved cane yield and enhanced economic benefits in a sustainable manner. Adoption of these practices, therefore, holds significant potential for reversing the constantly declining sugarcane yields at WSSE.

Prediction of Historical, Current, and Future Configuration of Tibetan Medicinal Herb Gymnadenia orchidis Based on the Optimized MaxEnt in the Qinghai-Tibet Plateau.

Climate change plays a pivotal role in shaping the shifting patterns of plant distribution, and gaining insights into how medicinal plants in the plateau region adapt to climate change will be instrumental in safeguarding the rich biodiversity of the highlands. Gymnosia orchidis Lindl. (G. orchidis) is a valuable Tibetan medicinal resource with significant medicinal, ecological, and economic value. However, the growth of G. orchidis is severely constrained by stringent natural conditions, leading to a drastic decline in its resources. Therefore, it is crucial to study the suitable habitat areas of G. orchidis to facilitate future artificial cultivation and maintain ecological balance. In this study, we investigated the suitable zones of G. orchidis based on 79 occurrence points in the Qinghai-Tibet Plateau (QTP) and 23 major environmental variables, including climate, topography, and soil type. We employed the Maximum Entropy model (MaxEnt) to simulate and predict the spatial distribution and configuration changes in G. orchidis during different time periods, including the last interglacial (LIG), the Last Glacial Maximum (LGM), the Mid-Holocene (MH), the present, and future scenarios (2041-2060 and 2061-2080) under three different climate scenarios (SSP126, SSP370, and SSP585). Our results indicated that annual precipitation (Bio12, 613-2466 mm) and mean temperature of the coldest quarter (Bio11, -5.8-8.5 °C) were the primary factors influencing the suitable habitat of G. orchidis, with a cumulative contribution of 78.5%. The precipitation and temperature during the driest season had the most significant overall impact. Under current climate conditions, the suitable areas of G. orchidis covered approximately 63.72 × 104/km2, encompassing Yunnan, Gansu, Sichuan, and parts of Xizang provinces, with the highest suitability observed in the Hengduan, Yunlin, and Himalayan mountain regions. In the past, the suitable area of G. orchidis experienced significant changes during the Mid-Holocene, including variations in the total area and centroid migration direction. In future scenarios, the suitable habitat of G. orchidis is projected to expand significantly under SSP370 (30.33-46.19%), followed by SSP585 (1.41-22.3%), while contraction is expected under SSP126. Moreover, the centroids of suitable areas exhibited multidirectional movement, with the most extensive displacement observed under SSP585 (100.38 km2). This study provides a theoretical foundation for the conservation of biodiversity and endangered medicinal plants in the QTP.

Pedological characteristics and classification of soils along landscape at highlands of Tsegede, Western Zone of Tigray, Ethiopia

Dynamics and distribution of soil characteristics as influenced by landscape /topographic features in acidic soils of Tsegede area in Northern Ethiopia has limited information. This study was conducted to characterize soil properties and classify major soil types. Four representative profiles along top sequence from varying slope positions crest at (Chegarkudo), upper slope and middle slope at (Endassilassie) and lower slope at (Intabela) were opened and described in-situ for morphological properties of soils and sampled horizon-wise for physico-chemical soil properties’ analysis. The results showed that soils at crest and upper-slope position were characterized by shallow depth, whereas those at middle and lower-slope positions exhibited relatively deep. The soil consistence ranges from slightly hard to hard (dry), friable to very friable (moist), yellowish red to dark red brown (dry) in color, moderate medium sub-angular to strong thick angular blocky in structure. The pH of surface soil ranged from 5.14 to 5.74 which was strongly acidic to slightly acidic and varied from clay loam to clay in texture, organic carbon, exchangeable bases and cation exchange capacity varied with profile depth. Based on the world reference base legend, the soils were classified as Skeletic Leptosols about 3756 ha, Cambic Leptosols about 1926 ha, Dystric Cambisols about 1883 ha and Leptic Cambisols about 1966 ha.

Evaluation of Soil Organic Carbon Stability in Different Land Uses in Lithuania

The effective management of soil organic carbon (SOC) is highlighted as one of the strategies and cost-effective options for mitigating climate change, while soil nitrogen (N) often is specified as an essential element for plant growth. This study was conducted to evaluate basic soil physical, chemical, and microbial indicators in three major soil types dominated in Lithuania—Arenosols, Retisols, and Cambisols—under forest land, perennial grassland, and arable land. Furthermore, soil microbial biomass carbon (SMBC) and nitrogen (SMBN), their ratio, and soil microbial respiration (microbial CO2) next to SOC and total N were hypothesized to be important measures for assessing SOC stability under different land uses. Therefore, selected soil indicators were evaluated in the surface 0–10 and 10–20 cm mineral soil layers. The study results showed higher concentrations of SOC, N, SMBC, and SMBN, and soil microbial CO2 in forest land and perennial grasslands than in arable land. The higher SMBC/SOC and SNBN/TN ratios indicated a higher ability to accumulate SOC and N in forest land and grasslands. Higher SOC immobilization in forest land and higher N immobilization in arable land were both specified by the obtained SMBC:SMBN ratio. This study identified forest land followed by grassland as the best land management practice that addresses soil C sequestration through higher C immobilisation. Assessing soil in forest land as a control land use next to the agricultural land could be a reasonable soil management practice to evaluate C sequestration in the region. Additionally, it was assumed that evaluation of the SMBC and SMBN concentrations together with soil physical and chemical indicators allow for a more effective assessment of SOC stability. Taken together, these findings support recommendation to develop grassland (and especially forest land systems) through afforestation or within agroforestry system, without reducing the importance of the agricultural sector.

Profile Distribution of Iron and Zinc in Soils formed from Three Different Parent Materials in Akwa Ibom State, Nigeria

The distribution of total and available levels of iron (Fe) and zinc (Zn) was studied in three major soil types derived from different parent materials in Akwa Ibom State. The parent materials were: Sandstone (SS), Coastal Plain Sands (CPS) and Beach Ridge Sands (BRS), respectively. Six representative soil profiles, two each for SS, CPS and BRS were dug. The soils from the different parent materials were sampled at different depths of 0 – 20, 20 – 40, 40- 60, 60 – 80, 80 – 100 and 100 – 120 cm. The soil samples were air dried, crushed and sieved using a 2mm sieve and stored in labeled bags for analysis. Laboratory analysis was conducted. The soils were strongly weathered, coarse in texture, acidic and generally low in fertility. Total Fe contents ranged from 365-1576mg/kg with sandstone soils having the highest mean of 1400mg/kg, followed by those of the coastal plain sand with a mean value of 883mg/kg and 485mg/kg for beach ridge sands. The total content of Zn followed the same trend ranging from 43 to 335mg/kg with a mean value of 246, 114 and 79mg/kg for the sandstone soils, coastal plain sands and beach ridge sand soils, respectively. Available Fe contents in the entire profiles ranged from 9.8 to 33.3mg/kg with sandstone having the highest mean value of 28.2mg/kg, followed by those of coastal plain sands with a mean of 14.7mg/kg and beach ridge sands with a mean of 12.2mg/kg. The available Zinc content followed the same trend. Available Zn content ranged from 4.2-20.0mg/kg with a mean value of 12.2, 9.3 and 6.5 mg/kg for the sandstone, coastal plain sands and the beach ridge sands, respectively. The distribution of the micronutrients in the soil profile was generally irregular, but in some profiles, it decreased with depth. The micronutrients were weakly correlated with organic carbon, clay and silt in the three parent materials. The available levels of the micronutrients in the soils were relatively high, having values above the critical levels of 4.5mg/kg for available Fe and 1mg/kg for available Zn. The result showed that the content of the two micronutrients were highest in sandstone soils, followed by that of coastal plain sands and least in the beach ridge sand. The high content of the available iron and zinc indicate possible toxicity effect to plant grown on these soils.

Soil-MobiNet: A Convolutional Neural Network Model Base Soil Classification to Determine Soil Morphology and Its Geospatial Location.

Scholars have classified soil to understand its complex and diverse characteristics. The current trend of precision agricultural technology demands a change in conventional soil identification methods. For example, soil color observed using Munsell color charts is subjective and lacks consistency among observers. Soil classification is essential for soil management and sustainable land utilization, thereby facilitating communication between different groups, such as farmers and pedologists. Misclassified soil can mislead processes; for example, it can hinder fertilizer delivery, affecting crop yield. On the other hand, deep learning approaches have facilitated computer vision technology, where machine-learning algorithms trained for image recognition, comparison, and pattern identification can classify soil better than or equal to human eyes. Moreover, the learning algorithm can contrast the current observation with previously examined data. In this regard, this study implements a convolutional neural network (CNN) model called Soil-MobiNet to classify soils. The Soil-MobiNet model implements the same pointwise and depthwise convolutions of the MobileNet, except the model uses the weight of the pointwise and depthwise separable convolutions plus an additional three dense layers for feature extraction. The model classified the Vellore Institute of Technology Soil (VITSoil) dataset, which is made up of 4864 soil images belonging to nine categories. The VITSoil dataset samples for Soil-MobiNet classification were collected over the Indian states and it is made up of nine major Indian soil types prepared by experts in soil science. With a training and validation accuracy of 98.47% and an average testing accuracy of 93%, Soil-MobiNet showed outstanding performance in categorizing the VITSoil dataset. In particular, the proposed Soil-MobiNet model can be used for real-time soil classification on mobile phones since the proposed system is small and portable.

English

The objectives of this study were to characterize, classify and evaluate the potential and constraints  of  the soils of Sakure and Nginda Payams in Nzara and Yambio counties in the Greenbelt zone of Western Equatoria State, South Sudan. Ten soil pits were dug, described and sampled based on FAO soil profile description guideline and samples were analysed using standard routine lab analyses for physical and chemical properties. Data generated were analysed statistically using the coefficient of variation (CV) and correlation. Results showed that top and subsoil were dominated by sandy clay loams. The soil reactions were strongly to slightly acidic (pH = 5.4 - 6.7). The most limiting nutrients were P and N. SOC was highest in the top soil and consistently decreased with depth, the CEC was low  (4 - 14.4 Cmol kg-1). The soils were classified into six major soil types: Ferralsol, retisols, acrisols, umbrisols, fluvisols, and chernozems. The soils have poor inherent soil fertility. It is recommended that further soil survey be carried out in the Greenbelt zone and  to conduct more research to determine the type of soil fertility management feasible. Key words: Acid soils, Nginda Payam, Sakure Payam, soil fertility management, shifting cultivation.

Endmember variability based abundance estimation of red and black soil over sparsely vegetated area using AVIRIS-NG hyperspectral image

Visible-near-and-short-wave-infrared hyperspectral images (HSI) have proven helpful for mapping the soil types over bare soils pixels. However, the accuracy of the traditional pixel-based classification methods decreases due to the spectral mixing between the significant agricultural features such as vegetation, soil and crop residue. In this context, spectral unmixing algorithms are handy for estimating the sub-pixel abundances of soil over sparsely vegetated areas. Most of the spectral unmixing methods focus on analyzing the HSI by considering the pixels as independent entities. However, in the HSIs of agricultural fields, the endmembers are spatially and temporally variable. It is also known that there exists a strong spatial correlation among neighbourhood pixels over agricultural fields. Therefore, both endmember variability and the neighbourhood spatial-spectral information are critical to estimate soil abundance accurately. Here we address the issue of estimating the abundances of two major soil types with spectral variability. The proposed approach combines the endmember bundle extraction with the spectral-spatial weighted unmixing approach (SSWU-SV). Experimental analysis has been carried out on the airborne HSI acquired by airborne-visible-and-infrared-imaging- spectrometer-next-generation (AVIRIS-NG) sensor. The quantitative analysis reveals that the proposed method consistently achieves a better unmixing performance than the traditional linear mixing model in terms of spectral angle mapper (SAM), and root-mean-square error (RMSE). Our results also indicate the saturation of normalized difference vegetation index (NDVI) at high vegetative fractions obtained from SSWU-SV.

The Nature of Soils and Their Agricultural Potential at Enemor Ener Woreda, Southern Ethiopia

Background: Availability of accurate soil data is necessary in understanding the nature of the soil and its status of the agricultural potential.
 Aim: Thus, a research was carried out to investigate physicochemical and morphological properties of the soils and characterize, classify and mapping them accordingly at Enemor Ener woreda, southern Ethiopia.
 Methods: Nineteen (19) representative pedons were opened from lower, middle and upper slopes and described them according to WRB (2014). Soil samples from each horizon were analysed for physicochemical properties.
 Results: Soils in the study area are so variable in their formation and nutrient availability. The major soil textural classes are clay loam and clay. Calcium the most dominant exch. bases whereas, Magnesium, sodium and potassium follow in decreasing order. The soil pH was ranged from strongly acidic to neutral reaction. Total nitrogen and organic carbons contents in all soils of the pedons are low to very low. Phosphorous content was ranged from optimum to very low content. Cation exchange capacity and percentage of the base saturation were ranged from very high to optimum, in regards to the micronutrients such as iron, manganese, copper and zinc in the soils were ranged from sufficient III to sufficient I. Major soil types revealed in the study area are Chromic Luvisols, Haplic Nitisols, Mollic Leptosols and Mesotrphic Vertisols.
 Conclusion: Soil properties and their potential status influenced by topography and land use type. Therefore, practice of soil integrated fertility management is vital for their sustainability.

Characterisation of organic carbon distribution and turnover by stable carbon isotopes in major types of soils in China

Environmental context Soil carbon sequestration plays an important role in achieving the goal of carbon neutrality. We studied the characteristics of organic carbon distribution and sequestration by stable carbon isotopes in nine types of soils in China and found that macro-aggregates possessed more organic carbon with a low degree of decomposition, while the overall direction of organic carbon transfer between aggregates was from macro-aggregates through micro-aggregates to the grain-size fractions of chalky clay. These results provide a foundation for understanding soil carbon sequestration in China’s cultivated lands. Rationale Soil is the largest carbon reservoir of terrestrial ecosystems. Studying carbon turnover in cultivated soils is vital for China to achieve its carbon neutrality goal. Methodology In this research, we investigated the distribution characteristics of soil organic carbon and its turnover among aggregates in nine major soil types in China by 13C stable isotopes. Results Since the second national soil survey in China 1979, the surface soil organic carbon (SOC) content of cultivated lands in boggy soils, black soils and dark brown forest soils in northeastern China has decreased (129.06, 2.70 and 7.78 g kg−1, respectively) while increased in cinnamon soils, brown soils, red soils, latosols, paddy soils and chestnut soils (0.85–7.79 g kg−1). Overall, the SOC content was highest in 1–0.25 mm aggregates, lowest in 0.053–0.02 mm aggregates and higher in <0.02 mm aggregates. The Δ13C value showed that the silt-clay size class fraction > micro-aggregates > macro-aggregates. Discussion The overall turnover direction of SOC among aggregates starts from macro-aggregates to micro-aggregates and ends with the silt-clay size class fraction. The result directly confirms both the ‘hierarchical development model’ and ‘embryonic development model’ of soil aggregate formation. The SOC flow direction and mobility potential between aggregates, as indicated by Δ13C values, suggest that cultivated soils are more susceptible to soil type than wasteland soils.

Nano- to Global-Scale Uncertainties in Terrestrial Enhanced Weathering.

Enhanced weathering (EW) is one of the most promising negative emissions technologies urgently needed to limit global warming to at least below 2 °C, a goal recently reaffirmed at the UN Global Climate Change conference (i.e., COP26). EW relies on the accelerated dissolution of crushed silicate rocks applied to soils and is considered a sustainable solution requiring limited technology. While EW has a high theoretical potential of sequestering CO2, research is still needed to provide accurate estimates of carbon (C) sequestration when applying different silicate materials across distinct climates and major soil types in combination with a variety of plants. Here we elaborate on fundamental advances that must be addressed before EW can be extensively adopted. These include identifying the most suitable environmental conditions, improving estimates of field dissolution rates and efficacy of CO2 removal, and identifying alternative sources of silicate materials to meet future EW demands. We conclude with considerations on the necessity of integrated modeling-experimental approaches to better coordinate future field experiments and measurements of CO2 removal, as well as on the importance of seamlessly coordinating EW with cropland and forest management.

Projected climate effects on soil workability and trafficability determine the feasibility of converting permanent grassland to arable land

CONTEXTAdapting to changes in climate and in consumer demand for commodities will force us to diversify land uses from the current status. Livestock grazing systems are dominant agricultural practices in the western regions of the British Isles. It has been suggested that grasslands in the region could be converted to other land uses, e.g. growing of cereal crops. We hypothesized that soil workability and trafficability would be important factors determining the feasibility and environmental impact of such conversion. OBJECTIVEObjectives were 1) to investigate the impacts of weather conditions under the current climate on agronomic management and crop yield of winter wheat using the SPACSYS model; and 2) to assess potential impacts of the land use conversion (grassland converted into arable land) on the environment under soil conditions representative of the region under baseline and future climatic conditions. METHODSUsing simulation modelling we investigated the impacts of baseline and future climates under the Representative Concentration Pathways (RCP2.6, 4.5 and RCP8.5) on soil workability and trafficability at sowing and harvest respectively of winter wheat and its consequences for crop productivity and key indices of environmental sustainability for three major soil types of the region.RESULTS AND CONCLUSIONS.Under baseline and future projections, the probability of successfully sowing winter wheat on these soils was between 38 and 76%. Simulations showed that grassland conversion to arable in the region would not be sustainable in terms of carbon sequestration with a decline in soil carbon stock of 165–280 kg C ha−1 yr−1 on average over the simulation period. Rates of decline were greater when soil workability was taken into consideration. Although CO2eq emissions from silage–based grassland soil were higher than those from the converted arable land, these were offset by the greater net productivity of grassland making it a larger net sink for carbon. When soil workability at sowing was considered, the NUEcrop (crop N content/N fertiliser applied) for winter wheat was lower than that for perennial ryegrass on all soil types under the baseline climate and RCP2.6, but comparable or greater under RCP4.5 and RCP8.5. In terms of carbon sequestration, grassland conversion for production of winter wheat is unsustainable under these soil–climatic conditions. SIGNIFICANCEOur results demonstrated that soil workability is a major factor influencing the potential impact of land-use conversion in clay soils and a wetter climate.

Genotype- by-environment interaction for marketable tuber yield in advanced potato clones using AMMI and GGE methods

Analysis of genotype-by-environment interaction (GEI) is critical in the local potato breeding and selection programme to obtain information on the performance of the genotypes for yield adaptability and stability. The objective of this study was to assess the marketable tuber yield of 18 advanced potato clones compared to the commercial variety Spunta at four locations (Bigara, Réduit, St. Antoine and Rivière du Poste), representative of four major soil types in Mauritius. They were analysed for adaptability and stability using the additive main effects and multiplicative interaction (AMMI) model and genotype main effect and genotype x environment interaction (GGE) biplot. Five clones gave significantly the highest marketable tuber yield in terms of overall ranking with yield increase of 47.4% to 59.6% over the control variety Spunta. AMMI analysis of variance detected significantly (P < 0.001) higher proportion of variation in marketable tuber yield due to environment (42%); followed by genotype x environment interaction (21%) which justified multi-locational testing. AMMI1 biplot demarcated clones 142/161/2 and 142/161/5 as high yielding and most stable while AMMI 2 biplot identified the winning genotypes for a specific environment. Thus, clones142/161/4 and 161/142/16 had specific adaptation to Bigara, 29/5/2 and 21/5/3 were adapted to St. Antoine, 21/5/10 to Rivière du Poste whereas 29/5/3 was adapted to Réduit. The GGE biplots identified clones 142/161/2 and 142/161/5 as the two most desirable genotypes close to the “ideal genotype”. The “which- won- where” view of the GGE biplot further pointed to the presence of two mega-environments, which corresponded to the sub-humid irrigated/humid environments (Réduit, St. Antoine and Rivière du Poste) and the high altitude super-humid environment (Bigara). These results showed that in future both AMMI and GGE methods can be integrated in the local potato breeding programme to select superior genotypes through multi-year and multi-locational yield evaluation.

Thoron activity concentration in Malaysian soil gas: Geogenic impact assessment

Given the rather short half-life of thoron (220Rn), at 56 s, its contribution to radiation exposure is often overlooked. Nevertheless, in a thorium (232Th) rich environment potential hazard does exist, in particular regarding prolonged duration exposures to 220Rn and its short-lived alpha-particle emitting progeny [polonium (216Po)]. Herein, concerning the geology and major soil types in the Malaysian state of Perak, an activity concentration map has been established for 220Rn in soil gas, with the use made of a RAD7 detector and the THORON protocol for in-situ measurements. The detector has been coupled to a soil probe driven to a depth of 0.8 m. The activity concentration of 220Rn in the soil ranged from undetectable to 563 kBq m−3 with a mean value of 38 ± 11 kBq m−3. Granite and Triassic-Jurassic formations in the region showed more elevated 220Rn activity while Quaternary and Silurian formations revealed low 220Rn values. Moreover, while elevated 220Rn activity concentrations were found in peat, riverine, and granite source soils, the activity concentrations in marine and other soils were low. A primary map of 220Rn in the soil gas has been developed based on geogenic impact assessment, with a greater 220Rn activity concentration in the central part of the state.

CYTOTAXONOMIC STUDIES ON NIGERIAN VERNONIA ADOENSIS LOWE & SOLADOYE

Nigeria, the study area lies between latitude 40 and 140 north of the equator and between longitudes 30 and 150 east of the Greenwich meridian with two major landforms- lowlands and highlands. The vegetation is made up of forests in the southern part and savanna in the northern part. The major soil types are ferruginous tropical soils, lithosols, vertisols, regosols, ferrasols and alluvial soils. Cytological and morphological studies were carried out on Nigerian Vernonia adoensis Lowe & Soladoye. Chromosome counts of n=10 was obtained for Vernonia stenostegia while V. tenoreana and V. kotschyana had n=9 which differed from earlier report. Pollen fertility test revealed that the 3 different species had normal regular bivalent pairing during meiosis, suggesting that they were diploids and hybridization was not responsible for their differences. Anonocytic stomata withagenous ontogeny was observed in all the 3 species, the epidermal walls of the 3 species differed from each other, the presence of contiguous stomata in V. tenoreana and the presence of eglandular multicellular trichomes in V. stenostegia and V. tenoreana is reported for the first time. the achenes of the 3 species differed from each other. Ecological, morphological and cytological observations have been discussed. They have proved that the habit and habitat preference is not responsible for their differences and thus V. adoensis was actually 3 species lumped together.

Studies on the Genesis of Soils in Jong River Basin in the Northern Province of Sierra Leone

The soil resources of Sierra Leone remain an integral part of sustainable agricultural development but knowledge of the suitability of soils and their management requirements for a variety of land uses is still lacking to a greater extent. In this view, a detailed soil survey of three chiefdoms in Northern Sierra Leone was undertaken to evaluate the genesis of soils and interpret soil-landscape properties and their relationships using the toposequence and free style approach of soil survey. Three major soil types, viz, gravelly, gravel-free over gravel and gravel-free soils, formed either directly or indirectly from weathered and disintegrated parent materials of two geologic origins namely Rokel River Series (comprising of sandstone, shale and mudstone), and Granite and Acid Gneiss were identified. The gravelly soils are formed from sandstone and sandy shales of the Rokel River Series, which upon weathering released iron and hydrated oxides that hardened into plinthite upon drying. The gravel-free over gravel soils are formed from acid gneiss containing acid and intermediate igneous and metamorphic rocks, which upon weathering produced sandy clay textured soils whereas the gravel-free soils are derived from sedimentary rocks (shales and mudstones) of Rokel River Series, which upon weathering and action of organisms produced sandy clay loam and sandy clay textured soils. The gravel-free over gravel soils are mostly located in the summit and back slopes and show dark brown to dark yellowish-brown hue and moderate chroma, weak to moderate structure and absence of coarse fragments in the 0 - 40 cm layer, and a strong brown hue and high chroma, very weak fine angular blocky structure having abundance of coarse fragments from 40 cm and above. In these soils, the compactness of ironstone and sandstone gravels increases with depth. The gravel-free soils are found on three landscape positions, viz, back slopes, foot slopes and toe slopes. On the back and foot slopes, the soils are characterized by very dark brown to dark yellowish-brown hue and high chroma, sandy loam to sandy clay texture, coarse angular to moderate sub-angular blocky structure and absence of coarse fragments throughout the horizon. In these soils, the clay content and sand grain sizes were observed to increase with depth. On the toe slopes, the soils show black to greyish-brown hue and low chroma, silty loam to sandy loam, structureless and high water holding capacity.

Regional soil moisture prediction system based on Long Short-Term Memory network

In the context of climate change, drought has been recognised as one of the most severe threats for agricultural production since absence of water is one of the most limiting factors for the growth of plants. In this study, a regional system for soil moisture prediction based on ERA5 climate reanalysis dataset, an open-source meteorological dataset issued by Copernicus Climate Change Service, was developed. It consisted of the relevant meteorological parameters for Serbia, during the period 2011–2020. Daily values of maximum and minimum air temperature, precipitation and vapour pressure deficit were used as features, and they were fed to recurrent neural network in order to predict volumetric soil moisture for three days ahead. A Long Short-Term Memory (LSTM) network was designed and trained at a regional scale using the data from the 2011–2016 period, at 28 locations that cover four major soil types. Validation was done on 2017–2018 data and LSTM was compared with a statistical forecasting technique and a classical machine learning approach. Evaluation was done with error measures commonly used in literature. The resulting network yielded the lowest errors and proved to have good generalisation properties. The system was tested from September 2019 to April 2020 using short-range weather forecasts of Yr service. It will present the cornerstone of the irrigation scheduling service in AgroSense.rs, the Serbian national platform for digital agriculture.