Extractable Cations
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2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Norbert W. Temba ◽  
Thomas Kivevele ◽  
Tatiana Pogrebnaya

The presence of elevated concentrations of carbon dioxide, hydrogen sulfide, ammonia, and trace impurities in biogas affect its caloric value as well as causes corrosion and is extremely toxic. There are various methods in existence for removal of these impurities, but most are chemically based and expensive and are limited in use. In our work, cryptogams (moss) integrated with soil and biochar packed in a filter have been employed for simultaneous removal of CO2, H2S, and NH3, from biogas. Different soil types rich in metallic oxides at different masses of 100 g, 150 g, and 200 g with a fixed mass of moss and biochar were tested in an on-site experiment to determine the removal efficiency (RE) and sorption capacity (SC). The adsorption dynamics of the filters were investigated at two flow rates, 80 ml/min and 100 ml/min, by determining removal efficiency. For the contribution of each substrate, sorption capacity and breakthrough time were determined by considering 5 g of each substrate that made up the filter. The soils with a high content of extractable cations showed excellent adsorption capacity for H2S by about 20 g S/100 g, which was higher than other adsorbents tested. It was found that integrated biofilter made up of bed arrangement of the soil, biochar, and moss plant improved the quality of biogas with SC of 11 g S and RE of 93% for H2S, 72% for NH3, and 68% for CO2.


Solid Earth ◽  
2015 ◽  
Vol 6 (2) ◽  
pp. 393-402 ◽  
Author(s):  
J. Young ◽  
T. K. Udeigwe ◽  
D. C. Weindorf ◽  
T. Kandakji ◽  
P. Gautam ◽  
...  

Abstract. Site-specific information on land management practices are often desired to make better assessments of their environmental impacts. A study was conducted in Lubbock, Texas, in the Southern High Plains of the United States, an area characterized by semi-arid climatic conditions, to (1) examine the potential management-induced alterations in soil salinity indicators in golf course facilities and (2) develop predictive relationships for a more rapid soil salinity examination within these urban landscape soils using findings from a portable X-ray fluorescence (PXRF) spectrometer. Soil samples were collected from managed (well irrigated) and non-managed (non-irrigated) areas of seven golf course facilities at 0–10, 10–20, and 20–30 cm depths and analyzed for a suite of chemical properties. Among the extractable cations, sodium (Na) was significantly (p < 0.05) higher in the managed zones of all the golf facilities. Soil electrical conductivity (EC), exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR), parameters often used in characterizing soil salinity and sodicity, were for the most part significantly (p < 0.05) higher in the managed areas. Water quality reports collected over a 22-year period (1991–2013, all years not available) indicated a gradual increase in pH, EC, SAR, total alkalinity, and extractable ions, thus supporting the former findings. Findings from the PXRF suggested possible differences in chemical species and sources that contribute to salinity between the managed and non-managed zones. PXRF-quantified Cl and S, and to a lesser extent Ca, individually and collectively explained 23–85% of the variability associated with soil salinity at these facilities.


2015 ◽  
Vol 7 (1) ◽  
pp. 91-114 ◽  
Author(s):  
J. Young ◽  
T. K. Udeigwe ◽  
D. C. Weindorf ◽  
T. Kandakji ◽  
P. Gautam ◽  
...  

Abstract. Site-specific information on land management practices are often desired to make better assertions of their environmental impacts. A study was conducted in Lubbock, TX, in the Southern High Plains of the United States, an area characterized by semi-arid climatic conditions, to (1) examine the potential management-induced alteration in soil salinity indicators in golf course facilities and (2) develop predictive relationships for a more rapid soil salinity examination within these urban landscape soils using findings from portable x-ray fluorescence (PXRF) spectrometer. Soil samples were collected from the managed (well irrigated) and non-managed (non irrigated) areas of seven golf course facilities at 0–10, 10–20, and 20–30 cm depths, and analyzed for a suite of chemical properties. Among the extractable cations, sodium (Na) was significantly (p < 0.05) higher in the managed zones of all the golf facilities. Soil electrical conductivity (EC), exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR), parameters often used in characterizing soil salinity and sodicity, were in most part significantly (p < 0.05) higher in the managed areas. Water quality report collected over a 22-year period (1991–2013, all years not available) indicated a gradual increase in pH, EC, SAR, total alkalinity, and extractable ions, thus, supporting the former findings. Findings from the PXRF suggested possible differences in chemical species and sources that contribute to salinity between the managed and non-managed zones. PXRF quantified Cl and S, and to a lesser extent Ca, individually and collectively explained 23–85% of the variability associated with soil salinity at these facilities.


Soil Research ◽  
2006 ◽  
Vol 44 (8) ◽  
pp. 783 ◽  
Author(s):  
A. J. Mills ◽  
M. V. Fey ◽  
A. Gröngröft ◽  
A. Petersen ◽  
T. V. Medinski

Relationships were sought between infiltrability and the properties of hundreds of surface soils (pedoderms) sampled across Namibia and western South Africa. Infiltrability was determined using a laboratory method, calibrated against a rainfall simulator, which measures the passage of a suspension of soil in distilled water through a small column packed with the same soil. Other properties determined were EC, pH, water-soluble cations and anions, ammonium acetate-extractable cations, organic C, total N, a 7-fraction particle size distribution, water-dispersible silt and clay, and clay mineral composition. Our objective was to ascertain whether general principles pertaining to infiltrability can be deduced from an analysis of a wide diversity of soils. To achieve this we compared correlation analysis, generalised linear models (GLMs), and generalised additive models (GAMs) with a segmented quantile regression approach, in which parametric regression lines were fitted to the 0.9 and 0.1 quantile values of equal subpopulations based on the x variable. Quantile regression demarcated relational envelopes enclosing four-fifths of the data points. The envelopes revealed ranges for soil properties over which infiltrability is potentially maximal (spread over a wide range) or predictably minimal (confined to small values). The r2 value of the 0.9 quantile regression line was taken as an index of reliability in being able to predict limiting effects on infiltrability associated with a variety of soil properties. Prediction of infiltration was most certain from textural properties, especially the content of water-dispersible silt (r2 = 0.96, n = 581), water-dispersible clay (0.88, n = 581), very fine sand (0.86, n = 174), and medium sand (0.84, n = 174). Chemical properties such as EC, sodium status, organic C content, and clay mineralogy were less clearly related to infiltrability than was texture. The role of fine-particle dispersion in blocking pores was highlighted by the stronger prediction in all statistical analyses provided by the water-dispersible as opposed to total content of silt and clay. All the statistical analyses revealed a probable skeletal role of medium and fine sand fractions in shaping pores and a plasmic (mobile) role of finer fractions in blocking pores. A noteworthy discovery was an apparent switch in role from skeletal to plasmic at a particle diameter of about 0.1 mm (i.e. between fine and very fine sand).


2003 ◽  
Vol 33 (12) ◽  
pp. 2321-2330 ◽  
Author(s):  
C SM Washburn ◽  
M A Arthur

Established species have been shown to affect soil nutrient availability, but the effects of "native invasive" species on soil nutrient availability are relatively unknown. Oak-dominated forests in the eastern deciduous forest are dynamic in their species composition, with increasing dominance of red maple (Acer rubrum L.) in the midstory and overstory. We hypothesized that higher quality red maple litter within a litter matrix dominated by oaks would accelerate N turnover, increase nutrient availability in the soil, and result in a thinner and less massive O horizon. We examined nutrient availability in soils under three overstory tree species (Quercus prinus L., A. rubrum, and Pinus echinata Mill. or Pinus rigida Mill.), under a shrub (Vaccinium spp.), and in locations without tree stems ("no tree"). Ex tract able nutrients (P, K, Mg, Ca) and total and available N were quantified in the O horizon and upper mineral soil at 0.5 m and 1.0 m from the base of individual trees or from the center of Vaccinium and no-tree locations. Despite low lignin concentration in red maple litter and low lignin/N ratio, the lowest N mineralization rates were found in red maple microsites; the highest N mineralization rates were found under oak. Extractable cations were generally highest under red maple and lowest under pines, and red maple had the highest levels of total N (but not NO3or NH4) in the upper mineral soil. Shifting species composition towards red maple and away from pines in these forests may alter nutrient cycling by increasing surface soil cation availability, but reducing soil N mineralization.


2002 ◽  
Vol 53 (12) ◽  
pp. 1349 ◽  
Author(s):  
J. W. D. Cayley ◽  
M. R. McCaskill ◽  
G. A. Kearney

Relationships between amounts of superphosphate applied to pasture and stocking rate on available nutrient status were assessed from 1979 to 2000 on a chromosol derived from basalt at Hamilton, Victoria. The pastures were stocked with sheep at low, medium, or high grazing pressures in factorial combination with 6 levels of superphosphate. Overall annual amounts of single superphosphate (8.8% P, 11% S, 19% Ca) applied ranged from 0.4 to 36 kg P/ha. Potassium chloride (KCl) was applied to all plots periodically. Average stocking rates ranged from 7 to 19 dry sheep equivalents (DSE)/ha. The nutrient status of plots was monitored by sampling the soil to a depth of 10 cm, avoiding the areas used by the sheep for camping. In 1994, samples of topsoil (0–5 cm and 5–10 cm) were taken from the camp areas and non-camp areas in each plot in order to assess 'plant-available' P, S, and extractable cations. Changes in P and S with depth to 80 cm in high and low grazing pressure treatments were also assessed. The influence of cumulative P applied on Olsen P varied with time and grazing pressure. During the first 12–15 years, the Olsen P of high grazing pressure plots was greater than that of low grazing pressure plots, but subsequently the reverse has been the case. Plant-available S also increased where more superphosphate had been applied. Levels were greater than 7 mg S/kg soil except at the lowest level of superphosphate, indicating that forms of P fertiliser with less S could be used here. After initial applications of KCl, this fertiliser was not applied for 8 years. During this time the K status fell from 270 to 120 mg K/kg soil, just above where plant responses to K are likely, emphasising the need to monitor the K status of productive pastures on these soils. Levels of exchangeable Mg2+ fell as more superphosphate was used, whereas levels of Ca2+ rose. The Olsen P of soil deeper than 10 cm was always less than 5 mg P/kg soil. P supply to deep-rooted pasture plants may thus be limiting when the topsoil is dry. These results, together with published assessments of animal production at this site, show that for pastures fertilised annually, the Olsen P associated with the most profit varied from 7 mg P/kg soil at 7 ewes/ha (10.5 DSE/ha), to 14 mg P/kg soil at 18 ewes/ha.


Soil Research ◽  
2002 ◽  
Vol 40 (4) ◽  
pp. 691 ◽  
Author(s):  
Nayan Ahmed ◽  
Chandrika Varadachari ◽  
Kunal Ghosh

Clay-humus complexes from 5 different soils (Entisol, Alfisol, Vertisol, and 2 Mollisols) were isolated by aqueous dispersion. Humic acid (HA) extractable from the complexes by alkali solutions ranging from pH 8 to 14, before and after acid pretreatment, were studied. Extraction by alkali solutions alone was not very effective except with the Alfisol sample. However, pretreatment by acid greatly increased extractability in all samples except the Alfisol. Maximum extraction of HA occurred at pH 12. In the Alfisol sample, clay-HA linkage is probably through hydrogen or other monovalent cation bridges which can be broken by alkali treatment. In Entisol and Mollisol II samples, cation bridging by higher valent, acid-extractable cations is dominant; both these modes are evidenced in the Mollisol I sample. The Vertisol sample has the strongest clay-HA links. TEM studies revealed a reduction in size of the montmorillonite particles in the Vertisol clay-humus complex (compared with humus-free clay); destacking and dispersion of montmorillonite occurred on HA complexation as observed previously for in vitro systems. Relative intensity of the 15� XRD line was much weaker in the Vertisol clay-humus complex than in the clay, lending further support to the fact that that c-stacking is disrupted during complexation of smectite with humus.


Nematology ◽  
2000 ◽  
Vol 2 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Johan Desaeger ◽  
Meka Rao

AbstractAn experiment in western Kenya tested the effects of six inoculum levels (0, 80, 400, 800, 2000 and 4000 eggs per 100 cm3 soil) of Meloidogyne javanica on nematode infection and growth of two Sesbania sesban provenences (Kakamega and Kisii) in six soils with sand contents of 26 to 82%. At 1 month after sowing, nematode infection, gall index and seedling mortality increased with inoculum level and sand/clay ratio. Gall index decreased and seedling growth improved with extractable cations, particularly calcium. At 3 months, nematode infection and damage were affected neither by soil texture nor by extractable cations. However, nodulation and plant growth decreased with increasing inoculum levels in all soils. Soils with higher cations and inherent fertility were less prone to nematode infestation and sustained better Sesbania growth irrespective of soil texture. It appears that as Sesbania grows it develops tolerance to M. javanica, suggesting that nematode infection is important at seedling stage primarily in determining stand establishment and early growth. Kisii provenance was more tolerant to the nematode and more productive than Kakamega. There is a need for screening a wide range of Sesbania germplasm for nematode resistance to select appropriate provenances and exploring low cost methods to minimise nematode damage to Sesbania at establishment stage. In einem Versuch in Westkenia wurde die Wirkung von sechs Inokulumstufen (0, 80, 400, 800, 2000 und 4000 Eier je 100 ml Boden) von Meloidogyne javanica auf die Nematodeninfektion und auf das Wachstum von zwei Herkünften von Sesbania sesban (Kakamega und Kisii) in sechs verschiedenen Böden mit Sandanteilen zwischen 26 und 82% untersucht. Einen Monat nach der Aussaat stiegen die Nematodeninfektion, der Vergallungsindex und die Keimlingssterblichkeit mit der Inokulumsgrösse und dem Sand/Lehm-Verhältnis an. Der Vergallungsindex nahm ab, und das Keimlingswachstum verbesserte sich mit dem Gehalt an extrahierbaren Kationen, insbesondere Kalzium. Nach 3 Monaten wurden Nematodeninfektion und Schaden weder durch die Bodentextur noch durch die extrahierbaren Kationen beeinflusst. Die Gallbildung und das Pflanzenwachstum nahmen jedoch in allen Böden mit steigenden Inokulumsstufen ab. Böden mit einem böheren Gehalt an Kationen und natürlicher Fruchtbarkeit neigten weniger zu Nematodeninfektionen und unterstützten das Wachstum von Sesbania unabhängig von der Bodentextur. Anscheinend entwickelt Sesbania mit zunehmendem Wachstum eine Toleranz gegenüber M. javanica. Das weist daraufhin, dass eine Nematodeninfektion im Keimlingsstadium in erster Linie wichtig ist für die Entwicklung des Standplatzes und für das frühe Wachstum. Die Herkunft Kisii war toleranter gegenüber den Nematoden und auch produktiver als Kakamega. Es muss eine breite Palette von Sesbania-Genplasmen auf Nematodenresistenz geprüft werden, um geeignete Herkünfte zu selektieren und preiswerte Methoden zur Minimierung des Nematodenschadens an Sesbania im frühen Entwicklungsstadium auszuprobieren.


Soil Research ◽  
1997 ◽  
Vol 35 (1) ◽  
pp. 131 ◽  
Author(s):  
R. A. Falkiner ◽  
C. J. Smith

Two tree species (Pinus radiata and Eucalyptus grandis) were planted in 1991 and irrigated weekly with either secondary-treated effluent or bore-water, in an effluent-irrigated plantation at Wagga Wagga, NSW. Changes in soil salinity, sodicity, alkalinity, and the accumulation of potentially toxic elements after 2 and 4 irrigation seasons were studied. The average sodium adsorption ratio (SAR) and electrical conductivity (EC) of effluent were 4·8 and 0·79 dS/m, while in bore water they were 3·3 and 0·70 dS/m, respectively. Effluent was applied at 3 rates: the water-use rate of the plantation less rainfall (medium treatment, M), a nominal rate 0·5 times M (low treatment, L), and a nominal rate 1·7 times M (high treatment, H). The bore-water treatment (W) was irrigated at its water-use rate less rainfall. Salinity of saturation paste extracts in the surface 0·05 m increased from a pre-treatment value of 1 dS/m to 2–3 dS/m after 4 years of effluent irrigation. The increase in soil salinity was consistent with the salt loading for the different irrigation treatments. Similarly, exchangeable sodium percentage (ESP) increased in all treatments. The ESP was generally <2% at the start of the experiment and increased to a maximum of 25% in the 0·3–0·4 m soil layer of treatment L. Values had changed throughout the 4 irrigation seasons and the soil profile does not appear to have reached a steady-state condition. Soil pH increased in all treatments. The largest increase (≈0·7) occurred in treatment H, while treatment W had the smallest increase (≈0·4). The increase in soil pH caused a decrease in exchangeable Al and Mn in the upper 0·4 m of the soil profile in all treatments. Effective cation exchange capacity (ECEC), approximated by the sum of the extractable cations, increased significantly in the upper 0·3 m of the soil profile after 2 and 4 irrigation seasons, but there was no significant change in ECEC below 0·3 m.


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