Soil CaCO3 Content Research Articles

Controlling Factors and Prediction of Lead Uptake and Accumulation in Various Soil-Pepper Systems.

Lead (Pb) is a typical toxic heavy metal element in soils and plants, which has a potential threat to human health through the food chain. Uptake of Pb in the soil-vegetable system has attracted broad attention, whereas reports on the main controlling factors of Pb uptake and accumulation in different soil-vegetable systems are limited. The effect of soil properties on Pb uptake and accumulation in pepper (Capsicum annuum L.) was studied by a pot experiment with 16 typical soils in China. The results showed that the Pb bioavailability was lower in alkaline soils, and that soil cation exchange capacity (CEC), CaCO3 , and total phosphorus contents might influence the uptake and transfer of Pb by peppers. Soil pH and CEC were the most significant factors affecting Pb accumulation in pepper fruits. Soil pH was negatively correlated with Pb uptake and accumulation due to its influence on Pb mobility and bioavailability. The accumulation of Pb decreased as soil CEC increased, which might inhibit the absorption and transfer of Pb in peppers. The multiple linear regression function based on soil Pb content, pH, and CEC could provide enough information for a good prediction of the accumulation of Pb in soil-pepper systems (R2 = 0.733). The results are in favor of developing a Pb threshold for vegetables in agricultural soils in China, thus improving the food safety of crops. Environ Toxicol Chem 2021;40:1443-1451. © 2021 SETAC.

Predictive Mapping of Solute‐rich Wetlands in the Canadian Prairie Pothole Region Through High‐resolution Digital Elevation Model Analyses

Prairie Pothole Region wetlands are integral in reducing nutrient mobility in prairie watersheds. Wetland soil CaCO3 content likely plays an important role in wetland phosphorus retention capacity. Accurate predictions of the spatial distributions of wetlands with CaCO3-enriched soils would allow for further study on these relationships and prioritized wetland conservation efforts to encourage this ecosystem service. Solute accumulations (including CaCO3) within wetlands are largely determined by the wetland’s topographic position and relationship with groundwater. These characteristics were estimated by predicting spill channel connections between wetlands using LiDAR-derived digital elevation models. Spatial distributions of solute-rich wetlands were predicted with a simple decision tree model that predicts wetlands as either fresh or solute-rich based on approximated hydrologic characteristics (Strahler order and terminal status) determined from the predicted active spill channel networks. The model was trained and tested using measurements of wetland pond water and soil electrical conductivity (i.e., solute-richness) in three study areas within the Saskatchewan Prairie Pothole Region. The model achieved acceptable predictive accuracies based on training and independent validation tests. The proposed methodologies could be incorporated into more complex multivariate models for the purposes of predictive soil mapping or hydrologic studies in the Prairie Pothole Region.

Biological reclamation of a calcareous sandy soil with improving wheat growth using farmyard manure, acid producing bacteria and yeast

Two pot experiments were performed in the Experimental Farm, Soils and Water Department, South Valley University, Qena, Egypt during two successive winter seasons (2018/2019 and 2019/2020). The main objective is to evaluate the effect of four addition levels of farmyard manure (FYM) (0, 10, 20 and 30 g/Kg of soil) combined with acid producing bacteria (APB) + molasses, yeast + molasses or their mixture on improving the chemical properties of a calcareous sandy soils and enhancing wheat growth. The results showed that, the results showed that with the increasing added level of FYM the soil pH and CaCO3 content were decreased and the soil EC, OM, total N and available P and K were increased. In addition, plant dry matter, N, P and K uptakes and use efficiencies were increased. Also, the application of APB + molasses, yeast+ molasses or their mixture with (FYM) were more effective than adding FYM alone in the improvement of calcareous soil properties and enhancement of wheat growth. It could be concluded that the best treatment in improving the calcareous sandy soil properties and increasing wheat growth, nutrients uptake and use efficiencies was the treatment of FYM with APB + yeast+ molasses especially when FYM was applied ate level 30 g/kg soil.

Initial soil aggregate formation and stabilisation in soils developed from calcareous loess

In soil, carbonates are important inorganic binding agents, controlling aggregate formation and soil structural stability. Until today, a clear understanding of the aggregate forming mechanisms in calcareous soil is missing. The objective of this study was to elucidate the initial aggregate formation in calcareous loess from the point when soil organic matter content was low and soil properties were mostly controlled by the parent material. We used a space-for-time chronosequence approach on agriculturally reclaimed loess soils in an open-cast lignite mining area in Garzweiler, Germany. We selected six time points from 0 to 24 years after reclamation in order to investigate the early processes of soil aggregate formation. Samples from two sampling depths (1–5 cm and 16–20 cm) were wet sieved into four size classes: silt- and clay-sized fraction (<63 µm), large microaggregates (63–200 µm), small macroaggregates (200–630 µm), and large macroaggregates (>630 µm). Each aggregate size class was characterized for soil organic carbon, total nitrogen and CaCO3 content. Organic matter amendment induced the formation of large macroaggregates (>630 µm), but we did not detect an accumulation of soil organic carbon neither in microaggregates nor in the silt- and clay-sized fraction. The silt- and clay-sized fraction contained large amounts of CaCO3 throughout the whole space-for-time chronosequence. This finding shows that in undeveloped loess material, microaggregation is controlled by cementation by carbonates inherited from the loess. These carbonates were likely easily dissolved during contact with water, therefore, aggregates in the early stage of soil development were not water-stable. Soil aggregate formation on young calcareous soils consists of two main mechanisms, 1. fresh soil organic matter predominantly contributes to macroaggregate formation, and 2. intrinsic cementing of loess through carbonates affects microaggregate stability. Therefore, the early stages of soil development in loess material do not show an aggregate hierarchy as we would expect in soils with high silt and clay content, such as Cambisols and Luvisols.

Ash dieback, soil and deer browsing influence natural regeneration of European ash (Fraxinus excelsior L.)

European ash (Fraxinus excelsior L.) dieback affects both overstory trees and natural regeneration. The decline of ash caused by severe crown defoliation and branch mortality has a high impact on ash natural regeneration. The site factors affecting the disease symptoms vary significantly and are not fully understood. Hence, we aimed to assess the joined effects of soil fertility and moisture (expressed by soil pH, CaCO3 content, and summer groundwater table level), herbivory, and health conditions connected with Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz, and Hosoya infestation on natural regeneration of F. excelsior. We examined 32 ash stands in Western Poland across soil fertility gradient. We established randomly selected circular plots (400 m2) in forests with ≥60% of ash in overstory species composition. We assessed natural regeneration density, the proportion of browsed trees, and trees damaged by ash dieback using generalized mixed-effects models. We found a higher proportion of damaged trees in neutral and base soils than in acid soils. Moreover, we found a low proportion of damaged trees in sites with low groundwater table levels. High CaCO3 content decreased the proportion of browsed trees, similarly as high shrub cover. The density of F. excelsior natural regeneration depended on groundwater table level, canopy cover, and proportion of damaged trees. We also found a positive relationship between density and deer browsing. The factor responsible for the higher infestation of saplings (low groundwater table level) also influenced natural regeneration density. This way, our study revealed how soil properties influence ash natural regeneration directly and indirectly. We showed that ash dieback will have a more severe impact on ash regeneration in ash typical sites. This is essential for predicting forest recovery and the ability to resilience after disturbances caused by H. fraxineus. CapsuleJoined effects of ash dieback, soil pH, and CaCO3 content, together with soil moisture, as well as deer browsing, affect ash regeneration.

Temporal changes of calcareous soil properties and their effects on cadmium uptake by wheat under wastewater irrigation for over 50 years

Calcareous soil has a strong buffering capacity for neutralizing acid and stabilizing cadmium (Cd) because of the high calcium carbonate (CaCO3) content. However, it is not clear whether the buffering capacity of calcareous soil can be maintained after long-term wastewater irrigation. We selected a typical area in western China that has been irrigated with wastewater for over 50 years to study the temporal changes of soil properties and their effects on Cd uptake by wheat. The results showed that compared with the background level before the 1960s, the soil pH and CaCO3 content in 2018 were lower by 0.80 units and 35%, respectively, while the soil organic matter (SOM) content, Olsen phosphorus (P) content, and soil total Cd content in 2018 increased by 1.54, 13.05, and 164 times, respectively. Due to the significant decrease in the soil pH and CaCO3, the high load of soil total Cd and electrical conductivity, the low soil clay content, and the coupling of SOM with soil nitrogen and P, the input Cd was activated. Furthermore, the activated Cd was effectively taken up by wheat roots and transported to grains with the assistance of dissolved organic carbon. Our results highlight that long-term wastewater irrigation caused irreversible damage to soil buffering capacity, resulting in the Cd activation and the enhancement of Cd uptake by wheat.

Impacts of Irrigation with Sewage Effluent on Physical and Chemical Parameters of Egyptian Soil آثار الری بمیاه الصرف الصحی على المعاییر الفیزیائیة والکیمیائیة للتربة المصریة

Egypt may soon suffer from water problems due to many factors, including the intransigence of upstream countries in addition to climate change and various pollution factors. Under these circumstances, many farmers are forced to use sewage water for irrigation, which may eventually lead to deterioration of soil and environmental quality. Therefore, the present investigation aims to study the influences of sewage water application for varied extended periods on some physical and chemical parameters of Abu-Rawash soil and to compare between the general properties of sewage effluent water and Nile water. In sewage effluent, Na+ was the dominant cation and EC, SAR, pH, and NH4+ values below the Permissible Maximum Level while nitrate content exceeds the safe level. The total N content in sewaged water was more than 13 folds that of Nile water. In sewage effluent irrigated soils, there are appreciable increases in clay fraction by 8.02 and 12.0 folds compared with the virgin soil. CaCO3 content of soil continuously irrigated with sewage water reduced as increasing period of application while there are an increasing in soil pH and EC. Only remarkably increase in ESP was occurred in the top soil layers of sewage irrigated soils. Bulk density and Hydraulic conductivity of sewaged soil decreases with increasing period of application and total porosity and available water capacity increased. The results reflect deficiency of nutritional status of uncultivated sandy soils in an arid zone, especially in N content.

Infectivity of the palm groves arbuscular mycorrhizal fungi under arid and semi-arid climate and its edaphic determinants towards efficient ecological restoration

Arbuscular mycorrhizal fungi (AMF) play a pivotal role in ecological restoration. To date, indigenous AMF remain unexplored but could be a potential resource for successful restoration programs. In this study, we evaluated the infectivity of AMF of five degraded oasis soils in Morocco (Marrakesh, Tafilalet, Draa, Tata-Guelmim and Figuig). Our data showed that mycorrhizal parameters; AMF spore number, MIP (mycorrhizal infectious potential) and AMF infection, in the arid palm groves soils, were more important than in the semi-arid ones. Principal component analysis (PCA) showed that the percentage of sand in the soil had a positive impact on AMF parameters, while soil available phosphorus, total nitrogen, electrical conductivity, organic matter, CaCO3 content, C/N ratio and clay percentage had a negative impact on these parameters. Results of the present study demonstrate that the mycorrhizal status of these palm groves soils is closely related to the edaphic parameters and suggest that native AMF can be used to restore ecological function of degraded oases in arid and semi-arid area.

Sugarecane molasse and vinasse added as microbial growth substrates increase calcium carbonate content, surface stability and resistance against wind erosion of desert soils

Wind erosion is one of the main factors of soil degradation and air pollution in arid and semi-arid regions. In this study we evaluated microbial-induced carbonate precipitation (MICP) as an alternative soil conservation method against wind erosion using sugar cane molasse and vinasse as growth substrates in comparison to tryptic soy broth (TSB). The three substrates were applied in laboratory tests with and without addition of MICP cementing solution (1 M urea plus calcium chloride) to two sandy soils differing in calcium carbonate content. The performance of MICP solution inoculated with a cultured urease-producing strain of Sporosarcina pasteurii was compared to that of an autoclaved MICP solution. For control we also performed a blank treatment without substrate, MICP solution and inoculation. In addition to lab tests in which we determined the effects of treatments on soil pH, electrical conductivity (EC), calcium carbonate (CaCO3) content and surface penetration resistance, we performed wind tunnel experiments to determine soil loss by deflation under different wind velocities. Applying vinasse and molasse strongly increased soil CaCO3 content and penetration resistance, with and without addition of inoculated or non-inoculated MICP solution. Vinasse generally had stronger effects than molasse, while TSB was less effective, especially on penetration resistance. The addition of MICP solution in most treatments did not enhance but rather decrease the substrate effects. In the treatments with vinasse and molasse, increase in penetration resistance translated into substantially decreased soil loss in the wind tunnel tests, down to around one third of the loss in the blank treatment. In contrast, soil loss substantially increased in the treatments with TSB, probably due to the high input of sodium with this substrate. Our results show that molasse and, even more, vinasse can have a strong soil stabilization effect against wind erosion, which is primarily related to the formation of CaCO3 content and does not depend on additional amendments. Thus, these substrates have a great potential to be used on their own as environmentally friendly and cost-effective amendments to control wind erosion of bare sandy soils in arid environments.

The response of soil Olsen-P to the P budgets of three typical cropland soil types under long-term fertilization.

The Olsen phosphorus (Olsen-P) concentration of soil is generally a good indicator for estimating the bioavailability of P and environmental risk in soils. To maintain soil Olsen-P at adequate levels for crop growth and environmental sustainability, the relationship between soil Olsen-P and the P budget (the P input minus the output) as well as the variations of soil Olsen-P and P budget were investigated from three long-term (22 years) experiments in China. Five treatments were selected: (1) unfertilized control (CK); (2) nitrogen and potassium (NK); (3) nitrogen, phosphorous, and potassium (NPK); (4) nitrogen, phosphorous, potassium and straw; (5) nitrogen, phosphorous, potassium and manure. The results showed that without P fertilizers (CK, NK), there was a soil P deficit of 75-640 kg ha-1, and the lowest P deficit (mean of CK and NK) was in Eutric Cambisol. Soil Olsen-P decreased by 0.11-0.39 mg kg-1 year-1 in the order of Luvic Phaeozems > Eutric Cambisol > Calcaric Cambisol. Soil Olsen-P and the P deficit had a significantly (P<0.01) positive linear relationship. For every 100 kg of P ha-1 of deficit, soil Olsen-P decreased by 0.44-9.19 mg kg-1 in the order of Eutric Cambisol > Luvic Phaeozems > Calcaric Cambisol. Under the P fertilizer treatments (NPK, NPKS, and NPKM), soil Olsen-P showed an obvious surplus (except the NPK and NPKS in Luvic Phaeozems) of 122-2190 kg ha-1, and the largest P surplus was found under the NPKM treatment at each site. The relation between soil Olsen-P and the experimental years could be simulated using quadratic equation of one unknown in Calcaric Cambisol for the lower P input after 14 years of fertilization. And soil Olsen-P increased by 1.30-7.69 mg kg-1 year-1 in the order of Luvic Phaeozems > Eutric Cambisol. The relation between soil Olsen-P and the P surplus could be simulated by a simple linear equation except under NPK and NPKS in Luvic Phaeozems. With 100 kg ha-1 P surplus, soil Olsen-P increased by 3.24-7.27 mg kg-1 in the order of Calcaric Cambisol (6.42 mg kg-1) > Eutric Cambisol (3.24 mg kg-1). In addition, the change in soil Olsen-P with a 100 kg P ha-1 surplus (soil Olsen-P efficiency) was affected by the soil organic matter (SOM), pH, and CaCO3 content, etc. In the practice of fertilization, it's not necessary to increase the amount of P fertilizers, farmers should take measure to solve the local problem, for adjust the soil pH of Eutric Cambisol and Calcaric Cambisol, and apply more nitrogen in Luvic Phaeozems. In the area of serious soil P surplus, it is encouraged to stop applying P fertilizers for a few years to take advantage of soil accumulated P and make the high Olsen-P content decrease to a reasonable level.

Susceptible soil organic matter, SOM, fractions to agricultural management practices in salt-affected soils

In the recent decades, soil salinity became the main human-induced soil degradation causes in Egypt’s Nile Delta Valley (ENDV) by affecting the stabilization processes of soil organic matter (SOM). However, soil organic carbon (SOC) is highly conserved by aggregating the stabilized organic molecules under sound agricultural management. In particular, labile SOM fractions assumed to be dually influenced by salinity and agricultural management practices other than the stabilized fractions. This work aimed to study various labile and stable SOM fractions that are more susceptible to the current agricultural practices in salt-affected soils of the ENDV area. Three different agro-ecological sites were studied: Eastern (EH, EM soils) and Western (WM, WL soils) Delta regions dominated by Vertic Torrifluvents, and Coastal region (NCH, NCM soils) dominated by Typic Calcitorrerts of high CaCO3 contents. Two different salinity levels were detected in each site; low in WL soils, medium in WM, NCM, and EM soils, and high in EH and NCH soils. The least values in EM, WL, and NCM soils were due to the recurrent legume applications. The carbon content of glomalin-related soil protein (GRSP) (C-GRSP) was positively correlated with SOC and water-extractable organic carbon (WEOC) fraction confirming the contribution of GRSP to the stabilization of SOM. The lower soil β-glucosidase, phosphatase, and protease enzymes activities were in those soils with larger salinity levels in each site as NCH < NCM, WM < WL, and EH < EM reflecting the effect of soil salinity and CaCO3 contents on soil metabolic activities. Extracted organic carbon (EOC) in both humic and fulvic fractions was higher in EH, WM, WL, and EM soils than in NCH and NCM soils. The chemical composition of SOM obtained by the pyrolysis gas chromatography showed that lignocellulosic and condensed aromatic structures in SOM increased significantly with CaCO3 and salinity. In conclusion, the considered SOM fractions such as WEOC, EOC, GRSP, C-GRSP, together with the pyrolytic results can be considered as significant indicators in the dynamic stability of SOM. Intercropping with legumes may increase the stability of SOM fractions in salt-affected soils of degraded lands. In calcareous soils, severe alteration in SOC conservation was observed and negatively influenced the active constituents of SOM.

The composition characteristics of arbuscular mycorrhizal fungal communities associated with barley in saline-alkaline soils in Central Anatolia

ABSTRACT Central Anatolia, which suffers from salinity, alkalinity, and drought stresses, is one of the most important cultivation regions of barley (Hordeum vulgare) in Turkey. Arbuscular mycorrhizal fungi (AMF) could promote barley production under several stresses; however, only a little information is available for AMF community composition in Turkish arable soils. In this study, barley root samples were collected from eight sites in the Central Anatolian region during the growing season (GS: April) and the harvest season (HS: July) in 2012, and the composition of AMF communities were elucidated based on the partial sequence of the AMF 18S rRNA gene using high-throughput sequencing technology. As a result, barley-AMF symbioses in this region were highly dominated by Glomeraceae (71.8% in GS and 59.2% in HS), followed by Claroideoglomeraceae (10.3% in GS and 15.9% in HS), Gigasporaceae (9.1% in GS and 13.1% in HS), and Acaulosporaceae (5.8% in GS and 7.7% in HS). Compared to Glomeraceae and Claroideoglomeraceae families, communities of Acaulosporaceae, Diversisporaceae, Paraglomeraceae, and Gigasporaceae consisted of fewer AMF species. The AMF evenness significantly increased from GS to HS. The most dominant AMF sequence, VTX00248 in the MaarjAM database, was closely related to Rhizophagus, which occupied 25.8% and 14.7% of the total AMF sequences in GS and HS, respectively. The relative abundance of AMF related to Rhizophagus tended to be reduced in HS, suggesting that the species could form mycorrhiza in the early stages of barley growth in this region. On the other hand, the relative abundance of Claroideoglomeraceae and Scutellosporaceae tended to increase in HS. Soil CaCO3 content significantly influenced AMF community compositions in GS, while soil pH and EC showed no significant impact on AMF community compositions. Based on discriminant analysis, 11 VTXs (related Acaulospora, Claroideoglomus, Funneliformis, Gigaspora, and Glomus) showed higher abundance in the barley roots grown in the soil with relatively high CaCO3 content, suggesting that these sequences might be adapted to such an environment.

Effect of Altitude on Forest Soil Properties at Northern Karakoram

This study aims to determine variation in soil physical, chemical and microbial properties along altitudinal gradients in fragile mountains region of the Karakoram. The soil samples were collected at the altitude ranging from 2787 to 3600 m from the alpine forest of the Bagrot valley, northern Karakoram, Pakistan and analyzed for various physical, chemical, and microbial parameters. The results indicate that there is a strong relationship of the soil parameters with altitude (p ≤ 0.01). With increasing elevation, soil bulk density, sand content, electrical conductivity (EC), pH, CaCO3 content, and 16S rRNA decreased significantly, while total porosity, saturation percentage, soil organic matter (SOM) contents, soil nutrients, and fungi-to-bacteria ratio increased with increasing altitude. These findings increase the understanding of dynamics of soil properties and enhance predictions of the responses of alpine soils to global warming.

Available macronutrient status of soils in various cropping systems of Thotapalli irrigation project ayacut of North coastal Andhra Pradesh

Assessment of macronutrient status of soils under five major cropping systems namely, rainfed mango/cashew orchards, rainfed groundnut/mesta cropping, irrigated rice followed by pulses, irrigated rice followed by maize and irrigated sugarcane in Thotapalli irrigation project ayacut area of north coastal Andhra Pradesh was carried out. A total of 125 random soil samples were collected from five different cropping systems from five villages of five Tehsils (mandals) namely, Cheeprupalli, Therlam (both tehsils from Vizianagarm district), Ranasthalam, Regidiamadalavalasa and Laveru (from Srikakulam district). The results of the study revealed that the soil organic carbon (OC), available nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) contents of the irrigated land was higher than adjacent rainfed upland, however the exchangeable calcium and magnesium were higher in rainfed uplands and relatively lower in irrigated cropping systems. Significant positive correlation was noticed between percent clay content with available N (r = 0.311**), available P2O5 (r = 0.232*), available K2O (r = 0.473**), available Sulphur (r = 0.249*), likewise organic carbon content also positively correlated with available N (r = 0.456**), available P2O5 (r = O.578**), available K2O (r = 0.211*) and available sulphur (r = 0.298*), while available phosphorous, was negatively correlated with soil pH, EC and CaCO3 contents. The variations in soil properties and nutrient status among cropping systems indicate need for employing integrated and soil test based nutrient management in sustainable manner.

Soils of Thotapalli Major Irrigation Project of North- Coastal Andhra Pradesh: Physical and Chemical Properties

Physical and chemical properties of the soils were assessed for the ayacut area of Thotapalli major irrigation project of North-Coastal Andhra Pradesh. Six representative soil pedons were studied in Devarapalli, Gujjangivalasa, Patikivalasa, Gangada, Aamiti and Maddivalasa villages falling in ayacut area of Thotapalli major irrigation project. The soil texture ranged from sandy loam to sandy clay loam in upland pedons while sandy clay loam to clay in pedons under cultivated plains. In general, relatively low bulk density was recorded at surface horizons compared to sub-surface layers. Maximum water holding capacity, pore space and volume expansion increased with soil depth. The soils were acidic to alkaline in reaction, non-saline, low to medium in organic carbon content. The CEC ranged from 6.4 to 32.5 cmol (p+) kg-1. The soil exchange complex was dominated by calcium followed by magnesium, sodium and potassium. The soils were found to be low in nitrogen, low to medium in phosphorus and medium to high in available potassium status. Manganese and copper were sufficient but zinc and iron were deficient in soils. The total silica (SiO2) content of pedons varied from 48.10 to 71.40 per cent. Sesquioxide (R2O3) and the molar ratio of SiO2 / R2O3 ranged from 19.01 to 32.4 per cent and varied from 3.74 to 6.59, respectively in different pedons. The SiO2 / Al2O3 ratio and the SiO2 / Fe2O3 ratio varied from 4.43 to 7.65 and from 13.7 to 47.8, respectively. A significant positive correlation of clay content with cation exchange capacity (CEC), maximum water holding capacity (MWHC) was observed. Sand content was positively correlated with silica and negatively correlated with MWHC and volume expansion. Soil organic carbon had a significant positive correlation with soil pore space, available nitrogen, phosphorous, potassium, zinc, manganese, copper and iron, but a negative correlation with soil bulk density. Soil pH was positively correlated with CaCO3 but negatively correlated with available phosphorous, potassium, zinc, manganese, and copper and iron. Soil CaCO3 content was negatively correlated with available phosphorous, potassium, zinc, manganese and copper and iron of the soil.

Soils of Thotapalli Major Irrigation Project of North- Coastal Andhra Pradesh: Physical and Chemical Properties

Physical and chemical properties of the soils were assessed for the ayacut area of Thotapalli major irrigation project of North-Coastal Andhra Pradesh. Six representative soil pedons were studied in Devarapalli, Gujjangivalasa, Patikivalasa, Gangada, Aamiti and Maddivalasa villages falling in ayacut area of Thotapalli major irrigation project. The soil texture ranged from sandy loam to sandy clay loam in upland pedons while sandy clay loam to clay in pedons under cultivated plains. In general, relatively low bulk density was recorded at surface horizons compared to sub-surface layers. Maximum water holding capacity, pore space and volume expansion increased with soil depth. The soils were acidic to alkaline in reaction, non-saline, low to medium in organic carbon content. The CEC ranged from 6.4 to 32.5 cmol (p+) kg-1. The soil exchange complex was dominated by calcium followed by magnesium, sodium and potassium. The soils were found to be low in nitrogen, low to medium in phosphorus and medium to high in available potassium status. Manganese and copper were sufficient but zinc and iron were deficient in soils. The total silica (SiO2) content of pedons varied from 48.10 to 71.40 per cent. Sesquioxide (R2O3) and the molar ratio of SiO2 / R2O3 ranged from 19.01 to 32.4 per cent and varied from 3.74 to 6.59, respectively in different pedons. The SiO2 / Al2O3 ratio and the SiO2 / Fe2O3 ratio varied from 4.43 to 7.65 and from 13.7 to 47.8, respectively. A significant positive correlation of clay content with cation exchange capacity (CEC), maximum water holding capacity (MWHC) was observed. Sand content was positively correlated with silica and negatively correlated with MWHC and volume expansion. Soil organic carbon had a significant positive correlation with soil pore space, available nitrogen, phosphorous, potassium, zinc, manganese, copper and iron, but a negative correlation with soil bulk density. Soil pH was positively correlated with CaCO3 but negatively correlated with available phosphorous, potassium, zinc, manganese, and copper and iron. Soil CaCO3 content was negatively correlated with available phosphorous, potassium, zinc, manganese, copper and iron of the soil.

Structural stabilization of soil backfill with quicklime

AbstractThe application of quicklime (CaO) to soil backfill for the amelioration of poorly aerated grave soils (sandy loam) was tested in a cemetery in Germany. Two grave simulations (soil pits 9 m × 2 m × 1.6 m, l × w × d) were set up. Variation sans was only excavated and refilled, while in variation qlm, 20 kg quicklime per m3 soil were added to the backfill. Soil matric potential and gas composition were recorded over a period of 24 months in the two refilled pits and in the surrounding undisturbed soil (ref) at the 50 cm and 135 cm depths, respectively. Soil samples were taken in the beginning from ref and in three‐month intervals from the treatments sans and qlm. Soil pH and CaCO3 content, as well as bulk density (ρB), air capacity (AC), air conductivity (kl), and saturated hydraulic conductivity (ks) were measured. Excavation and backfill of the untreated soil (sans) led to an increase in ρB at the 50 and 90 cm depths and decreases in AC, kl, and ks when compared to ref. Quicklime application led to an increase in pH, the formation of CaCO3 in the formerly carbonate‐free soil, consistently reduced ρB, and increased AC, kl and ks. Although the quicklime application did not lead to notably more negative matric potentials, it increased the O2 concentration in the soil air and reduced the CO2 concentration to zero. The results show that the application of quicklime helps the structural amelioration of cemetery soils even at relatively low clay contents.

Measurement of uranium distribution coefficient and 235U/238U ratio in soils affected by Fukushima dai-ichi nuclear power plant accident

Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted radioactive contamination in soil due to deposition of mainly radiocesium as well as many long-lived radionuclides surrounding a large area around FDNPP. Depending upon environmental conditions, radionuclides in soil can be mobilized in aquatic systems. Therefore, the fate and transfer of these radionuclides in the soil water system is very important for radiation protection and dose assessment. In the present study, soil and water samples were collected from contaminated areas around FDNPP. Inductively coupled plasma mass spectrometry (ICP-MS) is used for total uranium concentration. Emphasis has been given on isotope ratio measurement of 235U/238U ratio using thermal ionization mass spectrometry (TIMS) that gives us the idea about its contamination during accident. For the migration behavior, its distribution coefficient (Kd) has been determined using laboratory batch method. Chemical characterization of soil with respect to different parameters has been carried out. The effect of these soil parameters on distribution coefficient of uranium has been studied in order to explain the radionuclide mobility in this particular area. The distribution coefficient values for uranium are found to vary from 30 to 36000 L/kg. A large variation in the distribution coefficient values shows the retention or mobility of uranium is highly dependent on soil characteristics in the particular area. This variation is explained with respect to soil pH, Fe, Mn, CaCO3 and organic content. There is a very good correlation of uranium Kd obtained with Fe content. There is no enrichment of 235U has been noticed in the studied area.

Phenotypic plasticity of Artemisia ordosica seedlings in response to different levels of calcium carbonate in soil

Plant phenotypic plasticity is a common feature that is crucial for explaining interspecific competition, dynamics and biological evolution of plant communities. In this study, we tested the effects of soil CaCO3 (calcium carbonate) on the phenotypic plasticity of a psammophyte, Artemisia ordosica, an important plant species on sandy lands in arid and semi-arid areas of China, by performing pot experiments under different CaCO3 contents with a two-factor randomized block design and two orthogonal designs. We analyzed the growth responses (including plant height, root length, shoot-leaf biomass and root biomass) of A. ordosica seedlings to different soil CaCO3 contents. The results revealed that, with a greater soil CaCO3 content, A. ordosica seedlings gradually grew more slowly, with their relative growth rates of plant height, root length, shoot-leaf biomass and root biomass all decreasing significantly. Root N/P ratios showed significant negative correlations with the relative growth rates of plant height, shoot-leaf biomass and root length of A. ordosica seedlings; however, the relative growth rate of root length increased significantly with the root P concentration increased, showing a positive correlation. These results demonstrate that soil CaCO3 reduces the local P availability in soil, which produces a non-adaptive phenotypic plasticity to A. ordosica seedlings. This study should prove useful for planning and promoting the restoration of damaged/degraded vegetation in arid and semi-arid areas of China.

Phytoavailability of potentially toxic elements from industrially contaminated soils to wild grass

Topsoil and grass samples from 14 sites located in different distances from three copper mining factories and a copper smelter were collected in Srednogorie, Bulgaria. The paper discusses results of studies on the mobility of potentially toxic elements (As, Cd, Cr, Cu, Mn, Ni, Pb, Zn) from contaminated soils to wild grass Cynodon dactylon in terms of transfer (TF: soil to plant) and phytoavailability (PF: EDTA (ethylenediaminetetraacetic acid)-soluble to plant) factors. Soils located close to mine and smelter factories were heavily contaminated by As and Cu reaching levels up to 500 mg/kg and 2400 mg/kg, respectively for As and Cu. At seven sites arsenic and copper in grass were over the normal levels (1 mg/kg As; 20 mg/kg Cu). The content of Cu in grass averaged 63 mg/kg exceeding the maximum allowable for sheep. Relationship between PF and TF values was found for As, Cd, Cu, Ni, Pb, Zn but not for Mn and Cr. To some extent the soil pH, TOM (total organic matter) and CaCO3 content are related to the phytoavailability of As, Cd and Cu since for Zn and Pb this relation is attributed to Al- and Fe-content of soil. Statistically significant correlation coefficients were determined between the EDTA-soluble fraction of soil and content in grass in the case of As, Cd, Cr, Cu, Mn and Pb indicating the suitability of the short procedure for phytoavailability studies of those elements. The application of hierarchical cluster analysis and self-organizing maps of Kohonen made it possible to reveal specific hidden relationships between the soil variables and transfer factors as well as between the sampling locations. This additional information helps in more detailed interpretation of phytoavailability and transfer processes in the region of interest.The novelty in this study is achieved by careful consideration of the possibility of using EDTA extracts of the toxic metals in investigating of the phytoavailability and transfer processes soil/plant. Additionally, chemometric expertise used makes it possible to differentiate the behavior of each toxic metal in the processes studied. The combination of easy option for rapid extraction and intelligent data analysis gives a new perspective for contributions in explanation of the complex interactions between soils and plants when assessing pollution events in a certain environment.