A. K. Alva

Engineered carbon (biochar) prepared by direct pyrolysis of Mg-accumulated tomato tissues: Characterization and phosphate removal potential

An innovative method was developed to produce engineered biochar from magnesium (Mg) enriched tomato tissues through slow pyrolysis in a N2 environment. Tomato plants treated with 25mM Mg accumulated much higher level of Mg in tissue, indicating Mg can be substantially enriched in tomato plants, and pyrolysis process further concentrated Mg in the engineered biochar (8.8% Mg). The resulting Mg-biochar composites (MgEC) showed better sorption ability to phosphate (P) in aqueous solutions compared to the other four tomato leaves biochars. Statistical analysis showed a strong and significant correlation between P removal rate and biochar Mg content (R(2)=0.78, and p<0.001), indicating the enriched Mg in the engineered biochar is the main factor controlling its P removal ability. SEM-EDX, XRD and XPS analyses showed that nanoscale Mg(OH)2 and MgO particles were presented on the surface of MgEC, which serve as the main adsorption sites for aqueous P.

Nitrogen mineralization and transformation from composts and biosolids during field incubation in a sandy soil.

Field evaluation of nutrient release from composts is important to estimate nutrient contribution to crops, potential leaching of nutrients, and, ultimately, to determine optimum application rates, timing, and placement of composts. Field incubation and laboratory analyses were conducted to evaluate

AMMONIA VOLATILIZATION FROM DIFFERENT FERTILIZER SOURCES AND EFFECTS OF TEMPERATURE AND SOIL pH1

Improved understanding of nitrogen sources, environmental factors, and nitrification effects on NH 3 volatilization is needed for optimal management of nitrogen in crop production systems. In the laboratory, a sponge-trapping and KCl-extraction method was modified for measuring NH 3 volatilization from different N sources as affected by temperature and soil pH. The kinetics of NH 3 volatilization from four N sources surface applied to an Alfisol (a Riviera fine sand, pH 7.9) followed an initial rapid reaction, and then a slow reaction, which was adequately described by a Langmuir kinetic model. The potential maximum NH 3 volatilization (q m ) under the experimental conditions, as predicted by the Langmuir equation, decreased in the order: NH 4 HCO 3 (23.2% of applied NH 4 -N) > (NH 4 ) 2 SO 4 (21.7%) > CO(NH 2 ) 2 (21.4%) > NH 4 NO 3 (17.6%). With an increase in NH 4 -N application rate, NH 3 volatilization increased significantly for (NH 4 ) 2 SO 4 , CO(NH 2 ) 2 , and NH 4 HCO 3 but decreased for NH 4 NO 3 . Ammonia volatilization was minimal at the initial soil pH of 3.5 and increased rapidly with increasing pH up to 8.5. The potential maximum NH 3 volatilization increased by 2- and 3-fold, respectively, with an increase in the incubation temperature from 5 to 25 °C, and from 25 to 45 °C, respectively. The greatly enhanced NH 3 volatilization at 45 °C, compared with that at 25 °C, was related to the inhibition of nitrification at the high temperature, which increased the availability of NH 4 for NH 3 volatilization over a prolonged period of time.

Clinoptilolite zeolite and cellulose amendments to reduce ammonia volatilization in a calcareous sandy soil

Leaching of nitrate (NO3−) below the root zone and gaseous losses of nitrogen (N) such as ammonia (NH3) volatilization, are major mechanisms of N loss from agricultural soils. New techniques to minimize such losses are needed to maximize N uptake efficiency and minimize production costs and the risk of potential N contamination of ground and surface waters. The effects of cellulose (C), clinoptilolite zeolite (CZ), or a combination of both (C+CZ) on NH3 volatilization and N transformation in a calcareous Riviera fine sand (loamy, siliceous, hyperthermic, Arenic Glossaqualf) from a citrus grove were investigated in a laboratory incubation study. Ammonia volatilization from NH4NO3 (AN), (NH4)2SO4(AS), and urea (U) applied at 200 mg N kg−1 soil decreased by 2.5-, 2.1- and 0.9-fold, respectively, with cellulose application at 15 g kg−1 and by 4.4-, 2.9- and 3.0-fold, respectively, with CZ application at 15 g kg−1 as compared with that from the respective sources without the amendments. Application of cellulose plus CZ (each at 15 g kg−1) was the most effective in decreasing NH3 volatilization. Application of cellulose increased the microbial biomass, which was responsible for immobilization of N, and thus decreased volatilization loss of NH3–N. The effect of CZ, on the other hand, may be due to increased retention of NH4 in the ion-exchange sites. The positive effect of interaction between cellulose and CZ amendment on microbial biomass was probably due to improved nutrient retention and availability to microorganisms in the soil. Thus, the amendments provide favorable conditions for microbial growth. These results indicate that soil amendment of CZ or CZ plus organic materials such as cellulose has great potential in reducing fertilizer N loss in sandy soils.

Chemical Association Of Cu, Zn, Mn, And Pb In Selected Sandy Citrus Soils

Distribution of various forms of copper, zinc, manganese and lead in the surface horizon and the distribution of total metal concentrations in different soil horizons down to 150 cm depth in six soil series (representing Spodosols, Alfisols, and Entisols) under citrus production were investigated

Nutrient content of biomass components of Hamlin sweet orange trees

ABSTRACT: The knowledge of the nutrient distribution in trees is important to establish sound nutrientmanagement programs for citrus production. Six-year-old Hamlin orange trees [ Citrus sinensis (L.) Osb.] onSwingle citrumelo [ Poncirus trifoliata (L.) Raf. x Citrus paradisi Macfad.] rootstock, grown on a sandy Entisolin Florida were harvested to investigate the macro and micronutrient distributions of biomass components.The biomass of aboveground components of the tree represented the largest proportion of the total. Thedistribution of the total tree dry weight was: fruit = 30.3%, leaf = 9.7%, twig = 26.1%, trunk = 6.3%, and root =27.8%. Nutrient concentrations of recent mature leaves were in the adequate to optimal range as suggestedby interpretation of leaf analysis in Florida. Concentrations of Ca in older leaves and woody tissues weremuch greater than those in the other parts of the tree. Concentrations of micronutrients were markedly greaterin fibrous root as compared to woody roots. Calcium made up the greatest amount of nutrient in the citrus tree(273.8 g per tree), followed by N and K (234.7 and 181.5€g€per€tree, respectively). Other macronutrientscomprised about 11% of the total nutrient content of trees . The contents of various nutrients in fruits were: N= 1.20, K = 1.54, P = 0.18, Ca = 0.57, Mg = 0.12, S = 0.09, B = 1.63€x€10

Biogeochemistry of Trace Elements in Coal and Coal Combustion Byproducts

Introduction. 1. Coal Combustion Product (CCP) Production and Use: Survey Results B.R. Stewart. Environmental Effects from Power Plants. 2. Flue Gas Desulfurization (FGD) Residue: Potential Applications and Environmental Issues T. Punshon, et al. 3. Environmental Aspects of Power Plants Fly Ash Utilization in Deep Coal Mine Workings I. Twardowska. 4. Coal Ash From Thermal Power Plants in Finland: A Review A.K. Mukherjee, R. Kikuchi. 5. Environmental Behavior of Power Plants Fly Ash Containing Flue Gas Desulfurization (FGD) Solids Untilized in Deep Coal Mines I. Twardowska. Trace Elements in Size-Density Fractionated Fly Ashes and Ash Utilization. 6. Trace Elements in Indian Coal and Coal Fly Ash M.P. Khandekar, et al. 7. Concentrations and Distribution of Major and Selected Trace Elements in Size-Density Fractionated Fly Ashes S.V. Mattigod, et al. 8. Coal Fly Ash Chemistry and Carbon Dioxide Infusion Process to Enhance its Utilization K.J. Reddy. 9. Evaluation of Coal Combustion Products as Components in Disturbed Land Reclamation by the Baker Soil Test D.E. Baker, et al. 10. The Revival of a Failed Constructed Wetland Treating a High Fe Load AMD A.D. Karathanasis, C.D. Barton. Transport and Leachability of Metals from Coal and Ash Piles. 11. Leaching of metals from Soils Amended With Fly Ash and Organic By-Products A.K. Alva, et al. 12. Effect of Fly Ash and Sewage Sludge Amendments on Transport of Metals in Different Soils A.K. Alva, et al. 13. The Use of Cyclonic Ashes of Fluidized Bed Burning of Coal Mine Refuse for Long-Term Immobilization of Metals in Soil J. Vangronsveld, et al. 14. Impact of Coal Pile Leachate and Fly Ash on Soil and Groundwater G.S. Ghuman, et al. 15. Contaminant Mobility in Soil Columns Amended with Fly Ash and Flue Gas Desulfirization Gypsum C.F. Ishak, et al. Use of Coal Ash for Plant Growth. 16. Nickel, Lead, Cadmium, and Chromium Concentrations in Shoots of Maize Grown in Acidic Soil Amended with Coal Combustion By-products R.B. Clark, et al. 17. Fly Ash-Borne Arsenic in the Soil-Plant Syatem M.E. Summer, S. Dudka. 18. Effect of Rock Phosphate on Arsenic Uptake from Fly Ash Treated Mine Soil D.K. Bhumbla, et al. 19. Citrus Tree Growth and Fruit Production Response to Flue-Gas Desulfurization Gypsum A.K. Alva, et al. 20. A Review of Selenium Uptake, Transformation, and Accumulation by Plants with Particular Reference to Coal Fly Ash Landfills P.B. Woodbury, et al.

Relationship Between Ionic Strength And Electrical Conductivity For Soil Solutions

Activity of an element is a better predictor of plant growth response than its concentration. Ionic strength of the soil solution is an important property that is required to calculate ionic activity. Since its calculation requires measurement of all major cations and anions in solution, an alternative approach was sought to estimate it on the basis of a single measured property of solution. Griffin and Jurinak reported a linear relationship between ionic strength and electrical conductivity which was employed to predict ionic strength using soil solution samples from a wide range of soils subjected to varying treatments with respect to source of amendment, concentration of supporting solution, soil moisture content, and duration of incubation. This study has shown a very close agreement between ionic strength predicted using the Griffin-Jurinak relationship and the ionic strength calculated using concentration and valence values for all cations and anions in solutions. Furthermore, for the conditions of soil solutions from variable charge soils, the Griffin-Jurinak relationship was modified.

Leaching of nitrogen forms from controlled‐release nitrogen fertilizers

Abstract Application of soluble forms of nitrogen (N) fertilizers to sandy soils may cause leaching of nitrate N (NO3‐N) resulting in contamination of groundwater. The leaching loss of N may be reduced to a certain extent by the use of controlled‐release N formulations. A leaching column study was conducted to evaluate the leaching of urea, ammonium N (NH4‐N), and NO3‐N forms from selected urea‐based controlled‐release formulations (Meister, Osmocote, and Poly‐S) and uncoated urea under eight cycles of intermittent leaching and dry conditions. Following leaching of 1,760 mL of water (equivalent to 40 cm rainfall) through the soil columns, the recovery of total N (sum of all forms) in the leachate accounted for 28, 12, 6, or 5% of the total N applied as urea, Poly‐S, Meister, and Osmocote, respectively. Loss of urea‐N from all fertilizer sources was pronounced during the initial leaching events (with the exception of Meister). Cumulative leaching of urea‐N was 10% for uncoated urea while <1.7% for the cont...

Phosphorus in China's Intensive Vegetable Production Systems: Overfertilization, Soil Enrichment, and Environmental Implications.

Chinas vegetable production has experienced a rapid growth in recent years. Total production amounted to 522.7 million Mg (1 Mg = 10 g) in 2009, which was more than nine times that in 1980 and represented >50% of the world production. Meanwhile, excessive use of animal manures and chemical fertilizers in vegetable fields has brought various production and environmental challenges, including excessive accumulation of nutrients in soils and accelerated water pollution problems. In this study, we have evaluated the current status of phosphorus (P) in Chinas intensive vegetable production systems based on data summarized from nearly 100 publications plus results from our recent experiments. Gross overfertilization occurred in greenhouse (571 kg P ha) and open-field (117 kg P ha) vegetable systems compared with P removal in harvested crops (44 and 25 kg P ha) per season. Excess P input led to soil enrichment of labile P, measured as Olsen-P, averaging 179 (greenhouses) and 100 mg P kg (open fields) in the 0- to 20-cm soil depth, and in some cases led to P leaching, as evidenced by increases in Olsen-P and CaCl-P at the 40- to 60-cm soil depth. The vast majority of vegetable soils had Olsen-P exceeding the critical level (46.0-58.0 mg P kg) for optimum vegetable yield. Innovative policies and strategies are urgently needed to implement science-based nutrient management practices to attain sustainable vegetable production while protecting natural and environmental resources.