Application Of Chemical Amendments Research Articles

Ammonia emission factors from cattle production systems in Ireland – a review

Ammonia (NH3) emissions from livestock production contribute to environmental pollution. To address this challenge, the European Union (EU) National Emission Reduction Commitments Directive 2016/2284 (NECD) sets NH3 reduction targets for EU member states. In order to achieve these targets, several strategies have been evaluated under Irish conditions. A compilation of emission factors (EFs) from studies which evaluated these strategies is necessary to assess their effectiveness. This paper reports NH3 EFs from cattle production under Irish conditions. The results from the review show that the mean EFs from the deposition of dung, urine and urea applied to urine patches on grasslands were 4%, 9% and 8% total nitrogen (TN), respectively. EFs from the application of urea to urine patches were reduced by 28% after the addition of the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) to urea. The mean EF of 28% TN reported for urea fertiliser was almost 7 times higher than calcium ammonium nitrate (CAN). The inclusion of urease inhibitors with urea fertilisation on grassland led to EF reduction of up to 86%. The mean EFs from cattle houses, concrete yards, slurry storage pits and slurry landspreading were approximately 13%, 35%, 60% and 59% total ammoniacal nitrogen (TAN), respectively. The most effective NH3 abatement strategies for concrete yards and slurry storage were immediate cleaning of concrete floors (up to 89% reduction) after excreta deposition and the application of chemical amendments (sulphuric acid, acetic acid, alum and ferric chloride) to slurry in storage pits (up to 98% reduction), respectively. Low-emission spreading strategies and slurry acidification were effective at abating EFs after slurry application to land.

Phytoremediation of copper-contaminated soil by Artemisia absinthium: comparative effect of chelating agents.

Phytoremediation is a promising method for the removal of toxic trace elements, specifically of copper, from the contaminated soil in the mining regions of Armenia. Thereby, the objectives of our study were the assessment of copper accumulation capacity and phytoremediation suitability of wormwood (Artemisia absinthium L.), a potential metal hyperaccumulator, as well as the identification of the influence of some chelating agents and their combinations on copper phytoremediation effectiveness. The results of studies have shown that A. absinthium is a relatively well-adapted plant species with the ability to grow in copper-contaminated soils collected from the surroundings of Zangezur Copper and Molybdenum Combine (south-east of Armenia). The observed decrease in plant growth in contaminated soil was possible to restore by the use of ammonium nitrate. It was revealed that for the remediation of copper-contaminated soils by phytostabilisation method, A. absinthium could be grown without the application of chelating agents, as being a perennial herb, it is able to accumulate relatively high contents of copper in its root and do not transfer this metal to the above-ground part at the same time. As opposed to the phytostabilisation method, for the cleaning of copper-contaminated soils through phytoextraction method by A. absinthium, the application of chemical amendments is needed for the enhancement of copper bioavailability and for its intensive transportation to the above-ground part of the plant. Collating the effects of various chemical agents on the plant, we concluded that the growth scheme, when the application of NH4NO3, a promoter of plant growth, is combined with the joint use of citric and malic acids, can be applied as the most expedient approach for remediation of copper-contaminated soils by phytoextraction method.

Improving effect of potassium in organic amendments on sodic soils

ABSTRACT Sodification is a major soil problem that limits plant productivity in arid and semi-arid regions. For ameliorating sodic soils, the application of chemical amendments that can release calcium (Ca), which expels soil exchangeable sodium (Na), is the most widely accepted approach for solving this problem. However, an alternative more economical method would be desired in developing countries that have large areas of sodic soils. The goal of the present study was to examine the effectiveness of using compost to expel soil exchangeable Na. Composts made from cattle manure, rice straw, and rapeseed pomace were added to a sodic soil (Tongliao, Inner Mongolia, China) at mass ratios of 0 − 10%, and the soil was leached with water. Soil exchangeable cations in the forms of outer sphere and inner sphere complexes were then extracted successively and their concentrations determined. Changes in the soil dispersibility resulting from the addition of compost was also examined. The concentration of Na in both the outer sphere and inner sphere complexes decreased when rice straw or rapeseed pomace compost added, but this was not observed when cattle manure compost, which is abundant in water-soluble Na, was used. The amount of K in both forms increased with increasing rate of addition of each compost, suggesting that the K in the compost replaced both the Na that is adsorbed to soil by electrostatic attraction and by chemical interactions. The largest removal of Na, 73% for outer sphere complex and 93% for inner sphere complex, was attained in the case of rapeseed pomace compost, which had the largest water-soluble K/water-soluble Na ratio, at a mass ratio of 5%. The addition of compost also neutralized soil pH and reduced soil dispersion, the latter being effective in improving the physical properties of the soil.

Stabilization methods for the treatment of weathered arsenopyrite mine wastes: Arsenic immobilization under selective leaching conditions

The release of arsenic from weathered arsenopyrite mine wastes represents a grave environmental issue, especially when dealing with former mining areas. The evaluation and development of measures to manage this type of wastes in a sustainable and economic way are required. In this study different methods based on the application of chemical amendments were assessed as stabilization systems. For this purpose, weathered arsenopyrite mine wastes with the occurrence of amorphous ferric arsenates (AFA)/scorodite as main secondary products, as determined by X-ray diffraction (XRD) and polarizing microscopy, were used. Stabilization studies were performed employing two different amendments applied at diverse doses, namely a combination of calcite and ferric sulfate (CC + Fe(III) salt) and a by-product generated from the processing of aluminum salt slags (BP-AlOx). The efficacy of such treatments was assessed using both batch and column leaching essays. Under the equilibrium conditions imposed by the applied standard batch leaching tests, both of the treatments at their optimal conditions attained important reductions in the leachable As concentrations (95–98% and 52–79%, respectively), making mine wastes acceptable at controlled landfills as established by international legislation. Nevertheless, under flow leaching conditions the treatment employing CC + Fe(III) salt was shown not to be an appropriate long-term stabilization method. Conversely, the treatment with BP-AlOx proved to be more perdurable, decreasing considerably the As release (>50%) under prolonged leaching conditions. This stabilization system allowed simultaneously an important transformation of AFA to scorodite. Additionally, it partially neutralized the acidity generated from mine wastes without exceeding the pH values above which the solubilization of scorodite could be enhanced importantly.

Application of inorganic passivators reduced Cd contents in brown rice in oilseed rape-rice rotation under Cd contaminated soil

Immobilization of heavy metals by the application of chemical amendments is an eco-friendly, economical and effective method to remediate cadmium (Cd) -contaminated soils. Field experiments were conducted during 2016–2018 following oilseed rape-rice rotation with the application of inorganic passivators i.e., slaked lime (CaOH2>95%) and sepiolite (SiO2>50%, MgO>20%). The experimental treatments were comprised of: rice planting in winter fallow and without passivator (F-PA0); fallow with slaked lime (F-PA1); fallow with sepiolite (F-PA2); oilseed rape–rice rotation without passivator (R-PA0); rotation with slaked lime (R-PA1); and rotation with sepiolite (R-PA2). The slaked lime and sepiolite were applied after the harvest of rape at 2000 and 5000 kg ha−1, respectively. Results revealed that the Cd contents were reduced by 47.44–49.03% in brown rice for F-PA2 and 9.54–42.66% in soil for R-PA2. The superoxide dismutase (SOD) activity was decreased by 10.65–17.98%, the malondialdehyde (MDA) contents were reduced by 28.57% whereas the proline content was decreased by 32.61% under R-PA2. In addition, the filled grain percentage was improved by 6.87% (F-PA2) and 3.70% (R-PA1), respectively. Overall, rice sown after oilseed rape gave better yields than sown after fallow fields while application of slaked lime and sepiolite as passivator could be a potential management option to grow crops in metal polluted soils.

Leaching of Saline Calcareous Soil under Laboratory Conditions

Soil salinity is a major problem in Kerman pistachio (Pistacia vera) orchards which caused low pistachio’s productivity in recent years. Farmers excessively use gypsum and sulfuric acid amendments to remediate saline soils in their pistachio orchards overcoming this problem. The aim of this study was to investigate type of amendments and the pore volumes of water (PVs) required to efficiently leach excessive salts from saline-calcareous soil. Laboratory experiments were conducted using soil columns that were collected from a pistachio orchard near Kerman city. Four treatments, including irrigation water (control), sulfuric acid, gypsum, and dissolved gypsum were applied to remove salt from these soil columns with using different PVs of water. The concentrations of removed cations and salt from the soil columns were measured by analysis of effluent continuously. The results demonstrated that the effect of chemical amendments in removing soluble salts, sodium, magnesium and calcium was similar to irrigation water and did not differ significantly. Thus, irrigation water removed 62% of the total sodium, 73% of magnesium, and 70% of soluble salts from the soil column up to 1.5 PVs of effluent. Application of chemical amendments was not beneficial to infiltration rate in comparison with irrigation water. Thus, the efficiency of only 1.5 PVs of irrigation water without any amendments can be recommended as the appropriate strategy for practical reclamation of the studied soil.

Chemical Amendments of Dryland Saline–Sodic Soils Did Not Enhance Productivity and Soil Health in Fields without Effective Drainage

Core IdeasThe amount of land impacted by salinity or sodicity is increasing worldwide.Precision conservation can be used to target corrective treatments to problem areas.Chemical amendments did not enhance soil health or plant productivity in northern Great Plains soils that did not have effective drainage systems.The application of chemical amendments as preventative treatment in tile drained North America northern Great Plains fields did not improve soil health (water infiltration and microbial diversity) and either reduced or did not increase crop yields.These results were partially attributed to high subsoil bulk densities and low drainable porosities.A common restoration treatment for saline–sodic soils involves improving soil drainage, applying soil amendments (e.g., CaSO4, CaCl2, or elemental S), and leaching with water that has a relatively low electrical conductivity. However, due to high subsoil bulk densities and low drainable porosities, these treatments many not be effective in glaciated dryland systems. A 3‐yr field study conducted in three model systems determined the impact of chemical amendments (none, CaCl2, CaSO4, and elemental S) on plant growth, microbial composition, temporal changes in electrical conductivity (ECe), and the relative sodium content (%Na). Chemical amendments (i) either reduced or did not increase maize (Zea mays), soybean (Glycine max), and sorghum (Sorghum bicolor) yields; (ii) did not increase water infiltration or microbial biomass as determined using the phospholipid‐derived fatty acid (PLFA) technique; and (iii) did not reduce ECeor %Na. These results were attributed to high bulk densities and low drainable porosities that reducing the drainage effectiveness in the model backslope and footslope soils, the presence of subsurface marine sediments that provided a source for sodium and other salts that could be transported through capillary action to the surface soil, high sulfate and gypsum contents in the surface soil, and relatively low microbial biomass values. The results suggests that an alternative multistep saline sodic soil restoration approach that involves increasing exchangeable Ca+2through enhanced microbial and root respiration and increasing transpiration and soil drainage by seeding full season deep rooted perennial vegetation should be tested.

Effect of chemical amendments on remediation of potentially toxic trace elements (PTEs) and soil quality improvement in paddy fields.

Remediation of potentially toxic trace elements (PTEs) in paddy fields is fundamental for crop safety. In situ application of chemical amendments has been widely adapted because of its cost-effectiveness and environmental safety. The main purpose of this research was to (1) evaluate the reduction in dissolved concentrations of cadmium (Cd) and arsenic (As) with the application of chemical amendments and (2) monitor microbial activity in the soil to determine the remediation efficiency. Three different chemical amendments, lime stone, steel slag, and acid mine drainage sludge, were applied to paddy fields, and rice (Oryza sativa L. Milyang 23) was cultivated. The application of chemical amendments immobilized both Cd and As in soil. Between the two PTEs, As reduction was significant (p<0.05) with the addition of chemical amendments, whereas no significant reduction was observed for Cd than that for the control. Among six soil-related variables, PTE concentration showed a negative correlation with soil pH (r=-0.70 for As and r=-0.54 for Cd) and soil respiration (SR) (r=-0.88 for As and r=-0.45 for Cd). This result indicated that immobilization of PTEs in soil is dependent on soil pH and reduces PTE toxicity. Overall, the application of chemical amendments could be utilized for decreasing PTE (As and Cd) bioavailability and increasing microbial activity in the soil.

Efficiency of Chemical Amendments for Reducing Ecotoxicity in Heavy Metal Polluted Agricultural Fields

This study was conducted to evaluate effect of chemical amendments on reducing bioavailable fraction of heavy metals in soil along with ecotoxicological effect on earthworms, Eisenia fetida. Three different chemical amendments, lime (L), steel slag (SS), and acid mine drainage sludge (AMDS), were applied with varied application ratio (1, 3, 5%). Heavy metal contaminated soil was mixed with chemical amedments and earthworms, Eisenia fetida, were cultivated for 28 days. Bioavailable fraction of heavy metals (Cd, Cu, Pb, and Zn) extracted with 0.1N HCl was monitored and also, mortality, growth, and metal concentration in earthworm were assessed. Result showed that all three amendments had high efficiency to reduce bioavailable fraction of heavy metals in soil. In particular, lime showed the highest reduction rate of Cu (63.9-87.7%), Pb (7.90-24.65%), and Zn (40.83-77.60%) among three amendments. No mortality of earthworm was observed during experimental period except 3% and 5% AMDS treatment indicating that application of chemical amendments is safe in terms of ecotoxicological aspect. However, no positive correlation was observed between reduction of bioavaialble fraction of heavy metals in soil and earthworms. Overall, application of chemical amendments in agricultural field can be adapted for reducing bioavailable fraction of heavy metals and detoxification in soil.

Different response of silicate fertilizer having electron acceptors on methane emission in rice paddy soil under green manuring

Cultivation of green manure plants during the fallow season in rice paddy soil has been strongly recommended to improve soil properties. However, green manuring may impact greenhouse gas emission, methane (hereafter, CH4) in particular, under the flooded rice cultivation and thus, application of chemical amendments being electron acceptors can be an effective mitigation strategy to reduce CH4 emissions in irrigated rice (Oryza sativa L.) field amended with green manure. To investigate the effect of iron (Fe) slag silicate fertilizer (hereafter, silicate fertilizer), which was effective in reducing CH4 emission and increasing rice productivity, in green manure-amended paddy soil, the aboveground biomass of Chinese milk vetch (hereafter, vetch) was added at rates of 0, 10, 20, and 40 Mg (fresh weight) ha−1 before the application of silicate fertilizer, which was added at rates of 0 and 2.3 Mg ha−1. Silicate fertilization reduced the seasonal CH4 flux by ca. 14.5% and increased rice yield by ca. 15.7% in the control (no vetch application) treatment. However, CH4 production was increased by silicate fertilization in vetch-treated soil particularly at the initial rice growing stage, which was probably due to the enhanced decomposition of added organic matters by the silicate liming effect. In conclusion, silicate fertilization is not effective in reducing CH4 production in green manure-amended rice paddy soils and its use should be properly controlled.

Physicochemical and Biogeochemical Stabilization of Uranium in a Low Level Radioactive Waste Disposal Cell

An on-site disposal cell is being evaluated for the long-term disposition of materials generated by CERCLA (Comprehensive Environmental Response Compensation and Liability Act of 1980) remediation activities on the U.S. Department of Energy Oak Ridge Reservation (ORR), Oak Ridge, Tennessee. The leaching characteristics of the expected waste materials indicates that uranium concentrations in the leachate could exceed 30 mg/L. Addition of a geochemical barrier to the disposal cell design, or the application of chemical amendments to the waste materials, have been suggested as methods to reduce uranium levels in leachate leaving the disposal cell. Three promising approaches were identified: a) stabilization of mobile uranium by sulfate-reducing bacteria; b) stabilization of uranium as low solubility oxides by hydrated lime addition; and c) sorption of mobile uranium by a peat moss-based geochemical barrier in the disposal cell. Bench scale tests were conducted to evaluate the relative effectiveness of these three approaches. The results suggest that: a) a peat moss-based barrier would be effective in removing uranium initially, but long-term exposure to an alkaline leachate would result in the resolubilization and transport of uranium previously sorbed onto the peat moss; b) even large applications of hydrated lime to uranium-contaminated soils would not stabilize uranium in a high alkalinity, high pH environment; and c) mixed cultures of sulfate-reducing bacteria will greatly attenuate uranium levels (even in alkaline solutions) by precipitating it in the reduced form as UO 2 . Consequently, a geochemical barrier containing sulfate-reducing bacteria should be more effective than one using peat moss or hydrated lime.

The Stable Isotope Chemistry of a Native and Irrigated Typic Natrargid in the San Joaquin Valley of California

AbstractThe stable C and O isotope chemistry of native and irrigated Typic Natrargids was examined in order to determine the relationship between the climate and vegetation and the δ13C and δ18O of the native pedogenic carbonates (CaCO3) and the effect of irrigation on the CaCO3 in the cultivated soils. The native soil had a sparse vegetative cover consisting of grasses and salt tolerant shrubs, especially Atriplex polycarpa (Torr.), S. Wats. The δ13C of the CaCO3 reflected the mixture of C3 and C4 vegetation and the δ18O of the CaCO3 suggested that it had formed from soil H2O that had undergone extensive amounts of evaporation. At the time of sampling, alfalfa (Medicago sativa L.) was being grown on the irrigated soils. These soils had CO2 partial pressures of up to 7 KPa, nearly 20 times that of the native soil. The δ13C of the CaCO3 in the irrigated soils was not significantly different than that of the native soils which was due, in part, to the relatively small isotopic difference between the newly formed CaCO3 in the irrigated soil and much of that which occurred naturally. However, the δ18O of CaCO3 in the irrigated soils appeared to be shifted to more negative values than the δ18O of the native CaCO3. Based on the differences in the δ18O of the CaCO3 in the irrigated and native soils, it was semiquantitatively estimated that between 10 to 40% of the carbonate in the irrigated soils was newly formed or had dissolved and reprecipitated as a result of irrigation, increased biological activity, and the application of chemical amendments.