OC Content Research Articles

ALUMINUM WASTE CANS RECYCLING IN LAGOS STATE, NIGERIA: ANALYSIS OF SOIL AND WATER BENEFITS

The study empirically evaluated the environmental (water and soil) benefits of aluminum waste cans recycling in Lagos State, Nigeria. Soil samples were collected from three locations using a soil auger the locations were aluminum at the recycling site, soil 100m away from the recycling site, and soil 150m away from the recycling site. From each location, three soil samples were collected and taken to the laboratory for analysis of soil physicochemical properties and heavy metal contents using standard methods. Similarly, a random sampling technique was employed to collect 3 borehole water samples 100m away from the recycling site and 150m away from the recycling site using 750 millimeters of a SMART plastic container. The collected water samples were taken to the laboratory for analysis of heavy metals using standard methods. The results obtained revealed that high contents of physio-chemical properties of OC (2.96%), Ca (10.92 cmol/kg), Mg (0.77 cmol/kg), K (0.24 cmol/kg), Na (0.57 cmol/kg), exchange acidity (0.33 cmol/kg) and ECEC (12.46 cmol/kg) were found in soil 100m away from the recycling site. Also high content of Av. P (23.27 mg/kg) was found in soil 150m away from the recycling. The contents of OC, P, Ca, Mg, K, and ECEC increase with distance away from the recycling site. No significant variations were found in the contents of OC, TN, P, Ca, Mg, K, Na, ,Al and ECEC (p>0.05). The content of Fe (223.87 mg/kg) was found to be high at the aluminum waste cans recycling site (discharge point) and low in soil 150m away from the recycling site while high Mn (2.62 mg/kg) content was found in soil 150m away from the recycling site and low in soil 100m away from the recycling point. The contents of Fe, Mn, Pb,Cd and Zn were withwhomWHO maximum permissible level indicating low concentration in the soil. A negative and significant association was observed between Zn and Cd (rho = -0.812, p<0.05). High Fe (259.18 mg/L), Pb (2.49 m,g/L) and Zn (16.01 mg/L) contents were found in the wastewater (discharge point), while high Mn (56.42 mg/L) content was found in the borehole water sample. The contents of Fe, Mn, Pb and Zn were the above WHO permissible limit. Based on the findings, the study concluded that the government should set up modalities to control the discharge of substances into the soil and water.

Deriving parametric and probabilistic Kd values for fluoroquinolones in soils

The evaluation of the sorption affinity of fluoroquinolone antibiotics (FQs) in soils, by means of the derivation of solid-liquid distribution coefficients (Kd), is a valuable information for assessing their environmental mobility. Aiming to develop Kd (FQ) prediction tools in soils, in the first stage of this study we constructed a Kd (FQ) sorption dataset using current literature data. Furthermore, additional sorption and desorption data for norfloxacin were obtained in seven different soils of contrasting properties. Sorption isotherms of norfloxacin were linear under the experimental conditions tested and desorption percentages increased for scenarios in which low sorption was noted. Sorption tests in the same soils were then extended to ciprofloxacin, enrofloxacin and ofloxacin and pooled in the dataset, revealing comparable Kd (FQ) values among the FQ tested after analyzing the overall dataset consisting in 312 entries of Kd (FQ). A partial least square (PLS) regression model was then developed to predict values of Kd (FQ) based on specific relevant soil properties (i.e., pH, cation exchange capacity and organic carbon and texture information), and, for the first time, FQ properties (fraction of cationic FQ species) affecting sorption. Additionally, probabilistic, Kd (FQ) best estimates in soils were derived through cumulative distribution functions (CDFs) for the overall and for partial datasets created by grouping Kd (FQ) values according to key soil properties affecting FQ sorption (i.e., pH, organic carbon content and texture information). This latter approach permitted to derive more representative Kd (FQ) best estimates for the soils to be assessed, and with a lower related variability than that derived from the overall dataset. Best estimates Kd (FQ) values were > 1000 L kg−1 for most acidic to neutral soils, suggesting strong sorption, although lower sorption and thus higher environmental mobility may be expected in scenarios with soils with alkaline pH, low OC and high sand contents. SynopsisThis study aims to derive parametric and probabilistic Kd values for fluoroquinolone antibiotics in soils on the basis of a few relevant soil physicochemical properties.

Soil Fertility Status and Correlation of Available Macro and Micronutrients in Warangal District of Telangana State

Fertility status of red and medium black soils and their correlation studies were carried out insoils of Warangal District (R) of Telangana State. All samples in red and medium black soils were neutral to alkaline in reaction and pH values ranged from 7.25 to 8.56 by medium black soilfollowed (6.50 to 7.52) by red soil with mean values of 7.64 in medium black soilfollowed 7.53 in red soil. The EC varies from 0.08 to 1.90 dS m-1 in red soil and 0.08 to 2.17 dS m-1 in medium black soil.The calcium carbonate (CaCO3) content varies from 0.59 to 1.95% in red soil and 1.69 to 2.92% in medium black soil and maximum mean valuewas recorded in medium black soil (1.69%) followed by red soil (0.69%). Red soils were Loam to Clay loam whereas medium black soils were clay in texture. Organic carbon content ranges from 0.14 to 0.75% in red soil and from 0.50 to 0.79% in medium black soil with an average value of 0.38% in red soil and 0.53% in medium black soil. 81and 45% of soils were low, 15 and 55% in medium and none of the soil samples were found higher categoryin OC content in red soil and medium black soils, respectively. Available N, P, K and S content varied from 59 to 201kg ha-1, 14 to 133kg ha-1, 211 to 341kg ha-1 and 6.9 to 24.59 mg kg-1with mean values of 144 kg ha-1, 56 kg ha-1, 247 kg ha-1 and 19.26 mg kg-1 in red soils, respectively. In medium black soils available N, P, K and S content varied from 100 to 276 kg ha-1, 21 to 103 kg ha-1, 332 to 450 kg ha-1 and 10.50 to 41.40 mg kg-1with mean values of 177 kg ha-1, 54 kg ha-1, 398 kg ha-1and 27.40 mg kg-1, respectively. In red soils 100% samples were low in available N, 25%low, 32 % medium and 43% higher in available P2O5,1% medium and 99% higher in available K2O and 62% low and 38% medium in available S. In medium black soils 100% samples were low in available N, 22% low, 38% medium and 40% higher in available P2O5, 38% medium and 62% samples were higher in available K2O and 51% low and 49% medium in available S. The DTPA-Zn in 23% samples were deficient in medium black soil. In case of DTPA-Fe in 47 and 90% samples were found deficient in red and medium black soil, respectively. None of the samples in both soil groups were found deficient in Cu and Mn. In case of available-B in 29 and 34% samples were deficient in red and medium black soils, respectively. The data indicated that only 9.2% samples in medium black soil were deficient in case of available Mo. The nutrient index indicated that the red and medium black soils were low, medium and high in available N, P and K, respectively. Deficiency of micronutrients was in the order: Fe > B in red soils, Fe > B >Zn in medium black soils. Available N, P, K, S, Fe, Cu, Zn, Mn, B decreased, whereas Mo increased with increasing pH. Available N and P decreased, whereas K and S increased with increasing EC. Available N, P, K, S, Fe, Cu, Zn, Mn and B increased with increasing level of organic carbon.

Spatial variability of soil properties of intensively cultivated rice soils of selected command areas of Karnataka

The spatial distribution of soil properties and plant available Si was studied in three important rice producing command areas of Karnataka by collecting random georeferenced surface (0-15cm) soil samples using GPS and GIS techniques. The soil samples were analysed for different soil properties and plant available Si and the data along with GPS reading were used for the preparation of soil thematic maps using interpolation method and the interpolated maps were analysed with geostatistical parameters and the corresponding kriging maps for pH, electrical conductivity (EC), soil organic carbon (SOC), available nitrogen, phosphorus, potassium and plant available Si (CCSi and AASi) were prepared. These soil samples were categorized as low, medium and high as per criteria followed by soil testing laboratories. The content of soil pH, EC, OC, CEC, sand, silt and clay in surface soils varied from 5.2- 8.7, 0.05-0.49 dS m-1 , 2.2-17.5 g kg-1 , 3.6- 26.5 c mol (p+ ) kg-1 , 20.4-85.6, 0.9-59.7 and 1.9-47.8%, 15.7-65.4 mg g-1 and 19.2-106.7 mg g-1 , respectively. The available nitrogen (89.6- 313.6 kg ha-1 ) was low whereas, phosphorus (10.4-206.9 P2O5 kg ha-1 ) and available K2O (68.9-516.9 K2O kg ha-1 ) were low to medium in range. The CCSi and AASi content ranged from 15.7-65.4 mg g-1 and 20.0-106.7 mg g-1 , respectively

Particulate and mineral-associated organic carbon fractions reveal the roles of soil aggregates under different land-use types in a karst faulted basin of China

Soil aggregation has been recognized as the main mechanism of organic carbon (C; OC) stabilization, and OC dynamics within aggregates are closely linked to soil OC (SOC) sequestration. To unravel the roles of different-sized aggregates and the associated OC fractions in SOC accumulation, SOC stocks (SOCS), aggregate distributions, and OC fractions within aggregates were measured under five typical land-use types (cropland, grassland, shrubland, plantation forest, and natural forest) in a karst faulted basin, China. Land-use type had distinct effects on SOCS in the topsoil (0–10 cm) and along the soil profile (0–60 cm), and the primary factors influencing SOCS varied with the soil horizons. Plantation forest had the highest SOCS (51.2 Mg C ha−1) in the topsoil, whereas the SOCS in shrubland (182.7 Mg C ha−1) was distinctively higher than those of other land-use types across the soil profile. Soil microbial biomass C and mean weight diameter were the major factors driving SOCS variation in the topsoil layer and the entire soil profile, respectively. OC content within macroaggregates (>0.25 mm) was significantly positively correlated with the SOC content of bulk soil, whereas only the mass proportion of large macroaggregates (>2 mm) showed a positive relationship with SOC. Additionally, mineral-associated OC (MAOC) was the dominant fraction of SOC and was abundant in macroaggregates. However, particulate OC (POC) within aggregates was relatively enriched in the topsoil and microaggregates. Considering the decomposition and distribution characteristics of OC fractions in different-sized aggregates, we suggest that the POC/MAOC ratios of macro- and microaggregates could respectively reflect aggregate capacity to sequestrate MAOC and POC across different land-use types. Overall, shrubland is the optimal land-use type for rocky desertification control in the karst fault basin, due to the protection of POC and MAOC within different-sized aggregates.

Nitrogen input level modulates straw-derived organic carbon physical fractions accumulation by stimulating specific fungal groups during decomposition

Microbial-driven straw-derived soil organic carbon (SOC) sequestration plays pivotal role in promoting soil productivity and achieving C neutrality, while nitrogen (N) and phosphorus (P) input levels are the impetus of this process. However, our understanding of the microbial mechanism underpinning the straw-derived SOC fractions accumulation within aggregates under contrasting N and P application rates is rudimentary. Here, a 90-day incubation experiment was conducted to observe the dynamics of straw-derived SOC fractions accumulation within aggregates by adding C3 straw (natural 13C-labeled substrate) to a Mollisol (in which C3 plants had never been grown). Treatments included straw combinations of half N and regular P (N1/2 +P + SR), regular N and half P (N + P1/2 +SR) and regular N and P (N + P + SR). Regular N input accelerated the succession of the microbial community from bacteria-dominated to fungi-dominated and increased the contents of straw-derived particulate OC (POC) at 10 days and mineral-associated OC (MOC) at 30 days within aggregates. Differential abundance analysis and slopes of linear regression models showed that the fungal community, especially the core enriched taxon of Chaetomiaceae, was strongly positively correlated with straw-derived MOC after N input. Random forest models strengthened the view that N input rate and Chaetomiaceae richness may directly mediate straw-derived POC and MOC accumulation process, respectively, during incubation. To verify our conjecture, another 60-day incubation experiment was carried out to elucidate the effects of Chaetomium globosum inoculation and N application on SOC turnover after straw addition. Chaetomium globosum inoculation with regular N input promoted straw decomposition and SOC sequestration than other treatments, but no difference was observed in soil respiratory quotient compared with control. The slopes of linear regression model show the more significant and positive correlations between SOC content and Chaetomiaceae richness in the present study than data from previous references, impling the important role of Chaetomiaceae in SOC sequestration in Mollisols. Our work provides new ecophysiological angles for understanding the effect of Chaetomiaceae richness on the accrual of SOC in response to varying N levels in agroecosystems on the Northeast China Plain.

Pyrolysis Temperature and Application Rate of Sugarcane Straw Biochar Influence Sorption and Desorption of Metribuzin and Soil Chemical Properties

Pyrolysis temperature and application rate of biochar to soil can influence herbicide behavior and soil fertility. The objective was to investigate the effect of soil amendments with application rates of sugarcane straw biochar, produced at different pyrolysis temperatures, on the sorption–desorption of metribuzin in soil. The analysis was performed using high-performance liquid chromatography (HPLC). The treatments were three pyrolysis temperatures (BC350, BC550 and BC750 °C) and seven application rates (0, 0.1, 0.5, 1, 1.5, 5 and 10% w w−1). Amended soil with different application rates decreased H + Al and increased pH, OC, P, K, Ca, Mg, Fe, Mn, CEC and BS contents. Kf values of sorption and desorption of metribuzin were 1.42 and 0.78 mg(1−1/n) L1/n Kg−1, respectively, in the unamended soil. Application rates < 1% of biochar sorbed ~23% and desorbed ~15% of metribuzin, similar to unamended soil, for all pyrolysis temperatures. Amended soil with 10% of BC350, BC550 and BC750 sorbed 63.8, 75.5 and 89.4% and desorbed 8.3, 5.8 and 3.7% of metribuzin, respectively. High pyrolysis temperature and application rates of sugarcane straw biochar show an ability to immobilize metribuzin and improve soil fertility, which may influence the effectiveness in weed control.

Soil macroaggregates determine soil organic carbon in the natural grasslands of the Loess Plateau

Soil aggregates are generally thought to be the nucleus of all carbon sequestration mechanisms. However, the Loess Plateau, a typical region where a fragile ecosystem has gradually recovered, has high variability in soil aggregates due to differences in climate and soil properties; thus, the driving mechanism of soil aggregates to changes in soil organic carbon (SOC) content remain unclear. To determine the dominant mechanisms affecting SOC content, we performed a large-scale investigation of the aggregate size fractions, aggregate-associated OC, OC in bulk soil, and environmental factors of the natural grasslands across a climatic gradient (semi-arid to semi-humid) on the Loess Plateau. The results showed that the proportion of macroaggregates (MA) decreased but that of microaggregates (MI) increased in the soil from south to north on the Loess Plateau. MA content decreased with soil depth, whereas MI and the silt + clay fraction (SC) contents increased with soil depth. In addition, aggregate-associated OC decreased with soil depth. The contribution rate of macroaggregate-associated OCwf (MAFC) to OC in bulk soil from south to north in the Loess Plateau showed a trend of decreasing first and then increasing, and the contribution rates were 73.77 % (Fufeng), 62.29 % (Huangling), 32.78 % (Suide), 28.31 % (Shenmu), and 47.62 % (Dalad Banner), respectively. For the entire Loess Plateau, MAFC contributed the most to SOC in different soil layers and the contribution rates were 64.68 % (0–5 cm), 49.54 % (5–10 cm), 44.43 % (10–20 cm), and 37.23 % (20–30 cm), respectively. Across the considered depths and sites, the MA, MAFC, and OC content of MA had significantly (p < 0.05) positive direct effects on the OC in bulk soil. Furthermore, MAFC was mainly dependent on the OC content and proportion of MA. Therefore, these results indicated that the proportion of MA and OC content within MA dominated the OC dynamics in bulk soil in the Loess Plateau.

Inter-annual variability of source contributions to PM10, PM2.5, and oxidative potential in an urban background site in the central mediterranean

Airborne particulate matter (PM) is studied because of its effects on human health and climate change. PM long-term characterisation allows identifying trends and evaluating the outcomes of environmental protection policies. This work is aimed to study the inter-annual variability of PM2.5 and PM10 concentrations and chemical composition in an urban background site (Italy). A dataset of daily PM2.5 and PM10 was collected in the period 2016–2017, including the content of OC, EC, major water-soluble ions, main metals, and compared to a similar dataset collected in the period 2013–2014. Oxidative potential using DTT assay (dithiothreitol) was evaluated and expressed in DTTV as 0.39 nmol/min·m3 in PM10 and 0.29 in PM2.5 nmol/min·m3. PM source apportionment was computed using the EPA PMF5.0 model and source contributions compared with those of a previous dataset collected between 2013 and 2014. Multi linear regression analysis identified which source contributed (p < 0.05) to the oxidative potential of each size fraction. Inter-annual trends were more evident on PM2.5 with reductions of biomass burning contribution and increases in traffic contribution in the 2016–2017 period. Crustal contributions were similar for the two periods, in both size fractions. Carbonates were comparable in PM10 with a slight increase in PM2.5. Sea spray decreased in PM10. The DTTV of PM2.5 peaked during cold periods, while, the DTTV of the PM10-2.5 fraction peaked in summer, suggesting that different sources, with different seasonality, influence OP in the PM2.5 and PM10-2.5 fractions. Analysis showed that sea spray, crustal, and carbonates sources contribute ∼13.6% to DTTV in PM2.5 and ∼62.4% to DTTV in PM10-2.5. Combustion sources (biomass burning and traffic) contribute to the majority of DTTV (50.6%) in PM2.5 and contribute for ∼26% to DTTV in PM10-2.5. Secondary nitrate contributes to DTTV in both fine and coarse fraction; secondary sulphate contribute to DTTV in PM2.5 with negligible contributions to DTTV in PM10-2.5.

Influence of Copper Amendments on Soil Properties, Growth and Metal Accumulation by Mentha arvensis L.

A polyhouse study was conducted to assess the influence of copper amendments on the soil properties, plant growth parameters (fresh weight and plant height) and metal accumulation in Mentha arvensis L. The amendments of copper were 270, 500, 700 and 900 mg kg-1 in triplicate along with an unamended control. After 90 days of plant growth, the aerial parts of the plant were harvested and the physicochemical properties of the soil such as pH, EC, %OC, %OM and metal content in plant and soil were recorded. The pH and EC values were higher for the amendments as compared to the control. The pH (8.22) and EC (0.80 dS m-1) values were the highest for Cu270 mg kg-1 and Cu500 mg kg-1 amendments, respectively. The percentage of OC and OM was the highest (1.16%, 2.00%) for Cu500 mg kg-1. The plant height was maximum (36.30 cm) for the control plant while the fresh weight was maximum for Cu700 mg kg-1 amendment. The copper accumulation was observed to be the highest (19.3 mg kg-1) for the Cu500 mg kg-1 amendment and least (13.7 mg kg-1) for the higher amendment (Cu900 mg kg-1) showing that for all the amendments along with control, copper accumulation was within the permissible limit. Thus, growing medicinal and aromatic plants in the metal-rich soils can be a sustainable and environment-friendly approach to obtaining metal-free commercially important end products.

Spectroscopic and Kinetic Study of Sucrose Oxidation by Cr(VI) and Its Application in the Quantitative Analysis of Soil Organic Carbon

The percent organic carbon (%OC) is an important soil fertility measure that has important implications in agricultural productivity and food security. In this study, a UV-visible spectrophotometric technique was investigated and applied to quantify %OC from selected soil samples along a river basin that traverses agricultural farmlands, a forest and sewage treatment lagoons for a comparative survey purposes. The study was based on the measurement of absorbance of Cr(III) species that arise from oxidation of sucrose (which is 42.11% carbon) by dichromate ions which contain Cr(VI) species. The uv-visible spectrophotometric double beam wavelength scan measurements elucidated the conversion of Cr(VI) to Cr(III) ions and a calibration plot was developed with r2= 0.99. The analyte peak was identified in the region from 750 nm to 550 nm (the absorbing Cr(iii) species) with a turning point maximum at 576 nm. The kinetic profile of sucrose oxidation by the dichromate ions was studied via absorbance of Cr(III) and Cr(VI) as a function of the reaction time and was used to characterize the reaction model. The absorbance of Cr(III) as a function of reaction time fitted best into the non-linear Belehradek power function equation y=a(x-b)c,, where y = absorbance; x = time(s); a, b, c = are constants (r2 of 0.91). Kinetic analysis revealed that the reaction that leads to the formation of Cr(III) during sucrose oxidation proceeds via pseudo first-order kinetics (r2= 0.83). A comparative quantitative analysis indicated that the sewage treatment lagoons had the highest %OC content at about 5.5-6.6%OC. The soils sampled from the forest regions had about 4.6-5.8%OC whereas the river bank soils had the lowest levels at about 2.0-2.5%OC. A statistical t-test analysis showed that the %OC levels in sub-soils were significantly higher than those of the top-soils (p &gt; 0.05 at 95% CI).

Potential effects of laccase on the formation and accumulation of Fe-OM complexes in coastal saline paddy soil under straw and nitrogen fertilization

ABSTRACT The bindings of organic matter (OM) with iron (Fe-OM complexes) are important for soil carbon (C) sequestration. Our objective was to evaluate the role of laccase in the formation of Fe-OM complexes in a coastal saline paddy soil. The experiment included two factors: (1) two nitrogen (N) levels, 255 (N1) and 400 (N2) kg N ha−1; (2) three straw levels: 0 (S0), 4500 (S1) and 9000 (S2) kg C ha−1. The results showed that the combined application of straw and N fertilizer increased the content of Fe-bound OC and laccase activity, both of which were the highest in N1S1 treatment, which was 7.48% and 0.58 μmol g−1 h−1, respectively. The content of Fe-bound OC was positively correlated with laccase activity, Feam content and soil moisture content, but negatively correlated with pH. Both Fe-bound OC and laccase activity were positively correlated with aliphatic functional groups and hydroxyl or amidogen, while both were negatively correlated with aromatic functional groups. Therefore, laccase might promote the formation of Fe-bound OC by changing the chemical structure of OC. In addition, the combined application of straw and N fertilizer could change laccase activity by changing microbial community structure (e.g. Chloroflexi, Ascomycetes and Zygomycota).

Can soil type interfere in sorption-desorption, mobility, leaching, degradation, and microbial activity of the 14C-tebuthiuron herbicide?

Understanding the behavior in soil of herbicides applied PRE-emergence, such as tebuthiuron, is essential for more accurate weed management and less environmental impact. Thus, the objective of this research was to evaluate the effect of the physicochemical attributes of soils in 14C-tebuthiuron behavior. All studies were carried out by radiometric technique. The Kf and Kd values of 14C-tebuthiuron sorption were 30% and 35% higher in clay soil (1.15 mg(1–1/n) L1/n Kg−1 and 1.32 L Kg−1) compared to loamy sand soil (0.80 mg(1-1/n) L1/n Kg−1 and 0.85 L Kg−1, respectively). The desorbed amount was ∼19% higher in loamy sand soil compared to loamy sand soil, and this process was influenced by OC and clay content. The 14C-tebuthiuron leaching in clay soil was up to 10 cm depth, while in loamy sand soil was higher, up to 25 cm, and this difference can be explained by high mobility and low sorption of herbicide in loamy sand soil. 14C-tebuthiuron had a long persistence in both soils (DT90 of ∼385 and 334 d in loamy sand and clay soil, respectively). Although, the microbiological activity in soils differed little in the presence and absence of herbicide. Soil type interfered in 14C-tebuthiuron behavior, and then the application recommendation of this herbicide as a function of the physicochemical attributes of the soil is an alternative to increase efficiency in weed control and reduce the risk of environmental contamination.

NUTRIENT POTENTIAL FROM VERMICOMPOST OF TWO CONTRASTING ORGANIC WASTES USING TROPICAL EARTHWORM AND MOSQUITO NET AS CULTURE MATERIAL

The biochemical break down of plant litters by earthworm and the associated micro-organisms are the main process of humus development. Nutrient potential from vermicompost of two contrasting organic wastes using tropical earthworm (Eudrilus eugeniae) and mosquito net as culture material was studied. The organic wastes diet is fruit wastes (FRW) and vegetable wastes (VGW). Ten earthworms were inoculated to each of the eight (8) sacks. The result of the experiment after three (3) months and three (3) weeks inoculation showed that the Eudrilus eugeniae can be cultured in sack made from old window mosquito net and the vermicompost produced in each waste are of high-quality humus. The nutrient content of the vermicompost varied among the wastes. The pH level of the wastes was found to be alkaline of which VGW recorded higher value (9.15) compared to FRW. The OC content and electrical conductivity (EC) were significantly different among the treatments. Higher values of Na, OC, K, and P were recorded in FRW, while VGW recorded higher values in Ca, Mg and EC. The highest dry matter weight of 115.75gkg -1 of vermicompost was recorded in VGW as against 109.5gkg-1 recorded in FRW. Earthworm production measured by the number survived, number of cocoons, and biomass weight at the end of the study showed VGW as best culture for earthworm production. FRW did not record any cocoon at harvest. Findings of the study confirm that tropical earthworm - Eudrilus eugeniae can be easily used for high quality vermicompost production which is socioeconomically very beneficial for soil fertility improvement and sustainable crop production. The wastes and the earthworm are in abundance in the study area and within the reach of the farmer. The farmers are therefore encouraged to harness this technology for their soil and crop production.

Characterization and Taxonomic Classification of Soils under a Toposequence Located at North-Eastern Ghat Agro-Climatic Zone of Odisha, India

The present investigation was carried out to study the characterization and Taxonomy classification of soils under a Toposequence located at North-Eastern Ghat Agro-Climatic zone of Odisha, India. Three representative pedons of the Nayagarh district located in different topographic positions of upland (pedon 1), medium land (pedon 2) and low land (pedon 3) respectively were studied for their morphology, physico-chemical characteristics and taxonomic classification. Results show that the bulk density and particle density found with higher values in the lower horizon and lower values in the upper horizon. Total porosity values found to be higher in upper horizons and lower in the lower most horizons. The soil pH found to gradually increase with increasing depth in all three pedons. The OC content decreasing along with depth in all the pedons. In pedon 2 and 3, fully developed genetic horizons with distinct sub-horizons within the B horizon. However, in pedon 1, no such horizons are developed. The clay content increases in pedon 2 and 3 from upper sub-horizon to the lower sub horizon of B horizon with increasing depth which could be due to the process of illuviation of clay and development of argillic horizon (Bt). Pedon 1, are classified under order Entisols; while that of pedon 2 and 3 under soil order of Alfisols. Pedon 1, are classified under sub order Orthents, great group Ustorthents and sub group Typic Ustorthents; while that of pedon 2 and 3 are classified under sub order Ustalfs, great group Haplustalfs and sub group Udic Haplustalfs.

Morphological Feature and Physicochemical Characteristics of Soils under &amp;lt;i&amp;gt;Festuca&amp;lt;/i&amp;gt; spp. Dominant Steppe at High Mountain and Mountain of Khuvsgul, Mongolia

The morphology, physicochemical, humic substances and micromorphological characteristics of four soil profiles of the steppe dominant by Festuca lenensis (F. lenensis) at the high mountain and mountain of Khuvsgul, Mongolia were studied. Soils were classified as Regosols and Leptosols at high mountain steppe, Leptosols and Cambisols at mountain steppe. On a high mountain, the plant root distribution, OC, N and moisture contents were high due to its high precipitation and low temperature. The soils show immature characteristics with low available nutrients, weakly developed crumb structure, many semi- and undecomposed plant residues, and few little organic pigments with few excrements. The humic acids with immature to degraded characteristics indicate that the climatic condition of high mountains inhibits the soil decomposition process. Due to extremely different landform positions, there a sharp difference was observed between studied soils on high mountain steppe. On the summit with a flat position, the soil of TSO1 showed finer soil texture with higher CEC, exchangeable Mg2+ and humification degree of SOM compared with the soil of TSO2, which located on the steep slope. This confirms that the abrupt changes in landform on high mountain strongly affect the properties of topsoil. On the mountain steppe, the soil contains higher exchangeable Na+, exchangeable K+ and water soluble at topsoil; however, the plant root distribution, OC, N and moisture contents were lower than that of high mountain soil. Because of warmer air and soil temperature in comparison with that of high elevation, active turnover in humic horizon and chemical weathering process lead to higher available nutrients in mountain steppe. The degraded to well humified characteristics of humic acid, moderately developed crumb structure, a higher component of little organic pigment and many intact excrements indicate that the soil decomposition process and biological activity were higher than that of the high mountain steppe. Our finding suggests that the climatic condition dependent on altitude and landform position at the high mountain and mountain of Khuvsgul had a large impact and played a key role in the soil properties and characteristics of steppe dominant by F. lenensis.

Extraction, characterization, and optimization of biodiesel production from Pachira aquatica Aubl

Given the great energy demand to meet the needs of modern society, it is essential that new alternatives to replace fossil diesel are studied. And biodiesel is an alternative that has been gaining prominence on the world stage, mainly with the use of vegetable oils with a high lipid content, such as Pachira aquatica Aubl, also known as munguba. Given the above, the objective of this work was to extract the oil from the seeds of Pachira aquatica, evaluate the physicochemical characteristics of the oil and define the best conditions for catalytic mixing with temperature variation in the production of biodiesel from the oil obtained. Thus, the acidity index, saponification, refraction, peroxide, water content and fatty acid profile of the oil were evaluated. Fourteen treatments of biodiesel produced with different amounts of sulfuric acid and temperature were evaluated. They were analyzed for water content, specific mass, kinematic viscosity at 40 ºC, refractive index and ester content. It was found that the lipid content of Pachira aquatica seeds was 42.19% and its physical chemistry analysis showed that it can be used in the production of biofuels. There was a greater presence of saturated fatty acids, with a predominance of palmitic acid with 81.95%. Biodiesel produced from oil, on the other hand, showed higher production of esters in relation to the volume used at temperatures of 60 ºC and 0.6 mL of sulfuric acid, and that its properties showed that the plant can be a possible alternative for the production of biodiesel.

Regional differences in mineral weathering characteristics of zonal soils under intensive agriculture

A good understanding of mineral evolution and soil properties in the context of agricultural activities is important for soil utilization and management. To investigate the effect various forms of intensive agriculture in different climate regions on the evolution of phyllosilicate minerals and iron (hydr)oxides, three zonal soils were studied under various long-term agriculture with different fertilizers and using fallow soil as reference state. The phyllosilicate composition and Fe species of the clay fractions (<2 μm) were determined, and the detailed mineralogical differences together with selected soil specific properties were analyzed. The results were used to unravel the most likely reasons for the distinctive mineral weathering differences caused by the different conditions. The variation of the extent of mineral weathering of the soils was mainly controlled by climate conditions. The relatively arid climate restrained the chemical weathering in Orthic Entisols. In subtropic humid area, intensive agriculture promoted the decilication of Udic Ferrisols, resulting in a slignt increase in kaolinite content by <5%. However, in the temperate humid area the phyllosilicate mineral assemblage of Udic Isohumosols was sensitive to tillage and fertilization practices. This was mainly reflected by the mutual transformation between non-expandable illite and expandable vermiculite or smectite depending on the variation of K pool. This conclusion was supported by the significant positive correlations between illite and available K (P = 0.005) and between illite and slow-available K (P = 0.047). Compared with phyllosilicate minerals, the iron species and crystallinity indicated by Feo/Fed ratio were more susceptible to intensive agriculture. This could be inferred from the one order of magnitude larger variation coefficients of the Feo/Fed ratio in the three soils under different agriculture/fertilization than the variation of the Fed/Fet ratio. The key factor affecting the Feo/Fed ratio was the OC/Fed molar ratio. Highest values of the Feo/Fed ratio and its variation coefficients in Udic Isohumosols also illustrated that iron (hydr)oxides were more vulnerable to agricultural activities in the temperate monsoon climate region. It can conclude that it is necessary to manage the agricultural utilization of arable soils in temperate humid areas with more by specifically regarding the K and OC content for a good soil quality.

Soil and organic carbon redistribution in a recently burned Mediterranean hillslope affected by water erosion processes

Forest fires cause many changes in the physical, chemical and biological soil properties such as aggregation and soil organic carbon contents (SOC) as well as on soil hydrology and erosion processes. Most studies on post-fire soil erosion in Mediterranean environments have been plot-based and research at hillslope or broader scale is scarce. Understanding SOC nature, distribution and modifications, as produced by forest fires and erosion, has become crucial to model and define the role of soil erosion as source or sink of C, and to sustainably manage ecosystem services related to the soil resource. This research provides data about the loss and redistribution of soil and SOC in a Mediterranean forest hillslope burned with high severity, at the Natural Park of Sierra de Espadán, Spain. Soil was sampled in coupled hillslopes (ca. 0.25 ha) (BU: burned, CO: control) at bottom (depositional), middle (transport) and top positions (eroding) at two depths (0–2 cm, 2–5 cm), and under two environments (UC: under canopy soil, BS: bare soil). Sediments were collected after each erosive event along one year, and yields were calculated. Samples were analysed to assess aggregate stability (AS), size and density fractionations, SOC contents and stocks. The main hypothesis is that fire affects soil characteristics related to aggregation and SOC stabilization and, together with erosion processes, may modify SOC distribution within aggregates and the burned hillslope.Soils were in general very stable, but some differences in the results of the methods used were observed. Significant differences were found for the environment (under canopy vs bare) and soil depth but not for slope position. SOC content was high both at BU and CO with no significant differences. In the BU hillslope, a homogenization of SOC contents was observed along the hillslope, while in the CO, a higher SOC content was measured in the depositional and transport sites than in the eroding one. Similar trends were observed for SOC stocks. Only four erosive rain events were registered in this study, which generated no sediment yields in CO hillslope. In the BU one, sediment yields were measured (0.05–0.58 Mg ha−1, total 0.925 Mg ha y−1), which mobilised OC amounts ranging between 0.005 and 0.04 MgC ha−1. When samples were fractioned, changes were observed in the mass distribution of soil and sediment aggregates by size and density, and in the OC content between density fractions of BU soils with regard to sediment and CO soils.According to the results, effective post-fire management should be oriented to control and reduce the erosion of aggregates < 2 mm, which present the highest SOC content and are very prone to be transported off-site. This fraction should include all the partially burned biomass (free light material), which acts as a first mulching and contains high amounts of OC that should be kept within the burned hillslope to increase soil fertility, promote vegetation recovery and act as a C sink. In the BU hillslope, eroded free light material might be buried at the depositional site and if the conditions are favourable for its conservation, SOC accumulation would be promoted, which may have implications for its stabilization, and the role of soil erosion as a C sink.

Runoff and soil conservation effects in Nagpur mandarin orchard under a sub-humid tropical climate of central India

Limited availability of water and nutrients in soil affects the yield and longevity of citrus plantation. Conservation of rainfall runoff not only enhances water availability but improves the nutritional status in soil which might increase the orchard efficiency in citrus. Keeping this in view, a long term (7 years) experiment was imposed to study the response of Nagpur mandarin (Citrus reticulate Blanco) orchard in relation to fruit yield, water use, water productivity, sustainability of production and energy use efficiency to various conservation practices (CPs) on 12% land slope in a vertisol of central part of India. The CPs tested, against without conservation practice (WCP) were continuous trenching (CT) and staggered trenching (ST) alone and with grass mulch (GM). All the treatments were imposed in randomized block design (RBD) with 4 replications. The combined use of CT and GM conserved the highest rainfall runoff (48%), soil (51%), organic carbon (OC, 52%) and nutrients (43–53%) compared with WCP in mandarin orchard. The GM enhanced the available nutrients (N, P, K, and Cu) and OC contents in soil. The relationship between rainfall and runoff was linear (R2 = 0.85–0.93) in the plots with CPs, whereas in WCP plot, it was exponential (R2 = 0.88). However, the runoff was linearly related to soil loss under both CPs (R2 = 0.76–0.91) and WCP (R2 = 0.79). The empirical models developed were found reasonably accurate in predicting the runoff and soil loss with R2 value of 0.81–0.93 and 0.87–0.96, respectively. The soil water content was improved by 3–55% in different CPs compared with WCP. The CT with GM improved the fruit yield by 53%, utilizing 31% less water which resulted in 53% higher physical water productivity (PWP) and 123% higher irrigation water productivity (IWP) than that in WCP. The fruit quality (juice content, total soluble solids, acidity and ascorbic acid content) under CT with GM was better than that in WCP. The sustainability yield index (SYI) and energy use efficiency (EUE) under CT with GM were increased by 25.4% and 39.4%, respectively, compared with WCP. Overall, these results reveal that the CT with GM could be imposed to sustain and enhance yield and water productivity, by conserving rainwater and soil in citrus orchards of water scarce regions.