Tee Boon Goh

Trace element changes in soil after long-term cattle manure applications.

Manure application supplies plant nutrients, but also leads to trace element accumulation in soil. This study investigated total and EDTA-extractable B, Cd, Co, Cu and Zn in soil after 25 annual manure applications. The residual effect of 14 annual manure applications followed by 11 yr with no applications was also investigated. Manure was applied at 0, 30, 60 and 90 Mg ha(-1) yr(-1) (wet weight) under rainfed (treatments Mr0, Mr30, Mr60, and Mr90) and at 0, 60, 120 and 180 Mg ha(-1) yr(-1) under irrigated conditions (Mi0, Mi60, Mi120, and Mi180). The manure applications had no significant effect on soil B, Cd and Co content under both rainfed and irrigated conditions, but significantly increased total Cu and Zn content under irrigated conditions with Zn in Mi120 and Mi180 reaching the lower maximum concentration (MAC) level set by the European Community. Manure application also significantly increased EDTA-extractable Cd and Zn content in soil. Up to 27% of the total Cd (0.156 mg kg(-1)) and 21% of total Zn (38 mg kg(-1)) are found in EDTA-extractable form (Mi180 at 0-15 cm). EDTA-extractable Cd and Zn content was also significantly elevated in the irrigated residual plots due to the higher manure rates used. Thus, the impacts of cattle manure application on trace elements in soil are long lasting. Elevated Cd and Zn are a concern as other studies have linked them with certain types of cancers and human illnesses.

Changes in Macroaggregation and Associated Characteristics in Mine Tailings Amended with Humic Substances

Abstract The mine tailings of a former gold mine in Nopiming Provincial Park, Central Manitoba, Canada, was observed to be highly degraded in soil structure as well as other chemical and biological characteristics. The tailings are highly acidic (pH 3.5), contaminated with copper (2000 mg kg−1), have very low organic matter (2.3 g C kg−1), and cannot be revegetated by native species. To reclaim the mine tailings, humic substances (HSs) and lime, with or without wheat straw, were incorporated in the tailings and then incubated up to 24 weeks. After incubation, a significant increase of macroaggregates, especially 2- to 20-mm aggregates, was observed in the HS-amended tailings corresponding to the length of incubation and doses of HS. Wheat straw initiated microbial activity in the mine tailings and also showed increase of the macroaggregation. Lime was less effective than HS in the formation of the macroaggregates. The amendments increased organic carbon (OC) in the mine tailings, which remained greater than in the control samples throughout the incubation period. However, the OC in each amended sample decreased over the period of incubation. There was an increase of microbial biomass carbon (MBC) in the straw-amended tailings throughout the incubation period, and the increase was highest at 12 weeks. The HS amendment increased the pH of the mine tailings from 3.5 to 5 as well as the cation exchange capacity (CEC). Macroaggregation of mine tailings was found to be highly correlated with OC and CEC. Significant correlations were also observed between OC and MBC and between OC and CEC.

Determination of the Geochemical Weathering Indices and Trace Elements Content of New Volcanic Ash Deposits from Mt. Talang (West Sumatra) Indonesia

Since the Indonesian archipelago is part of the very active and dynamic Pacific Ring of Fires, the volcanic eruptions occur from time to time. Immediately after the eruption of Mount Talang in West Sumatra (April 12, 2005), volcanic ashes, both unleached and leached were collected. The deposits from Mt. Talang were andesitic to basaltic in composition. The volcanic ash consisted of volcanic glass, plagioclase feldspar in various proportions, orthopyroxene, clinopyroxene, olivine, amphibole, titanomagnetite. We conducted the total elemental analysis of the bulk samples of the volcanic ash. The contents of major, trace and rare elements as well as heavy metals were determined by wet chemical methods and x-ray fluorescence (XRF) analyses. Although the volcanic ash of Mt. Talang are still very new, an evaluation of the geochemical weathering indices was performed with the objective of showing the volcanic ash condition at the early stage of weathering. Eight weathering indices were evaluated. The results showed that the unleached volcanic ash has higher Ruxton Ratio (R), Weathering Index of Parker (WIP), Product of Weathering Index (PWI) and Silica Titanium Index (STI) values compared to the leached ash, while the leached ash exhibited higher Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), Vogt’s Residual Index (VO), and Plagioclase Index of Alteration (PIA). These weathering indices can be used to quantify the condition of the volcanic ashes at the initial stage of weathering, to evaluate their fertility, to provide a better understanding of element mobility during weathering, and predict the source of soil nutrients as well as determine the products of primary minerals alteration.

Atrazine sorption by hydroxy-interlayered clays and their organic complexes

This study examined the sorption of atrazine by hydroxy-Fe interlayered montmorillonite (FeMt) and its hydroquinone (FeMtHQ), citrate (FeMtCt) and catechol (FeMtCC) complexes as well as by hydroxy-Al interlayered montmorillonite (AlMt) and its hydroquinone (AlMtHQ) and citrate (AlMtCt) complexes. Found among the clays were sorption distribution coefficients (Kd) ranging from 24 to 123 mL g−1 and maximum sorption (M) ranging from 2.2 to 16.8 μ g g−1. Both Kd and M decreased in the order of FeMtCC > FeMtHQ > AlMtHQ > (AlMt = FeMt) > (AlMtCt = FeMtCt). The pH was negatively correlated with both Kd (r = −0.90, p < 0.001) and M (r = −0.81, p < 0.001). When interlayered clays were associated with humified material (FeMtCC, FeMtHQ, AlMtHQ), both Kd (r > 0.96, p < 0.01) and M (r > 0.94, p < 0.01) were highly positively correlated with total organic C and alkali-soluble C. However, clays with non-humified organic compounds (FeMtCt and AlMtCt) sorbed less atrazine than clays without any organic C (FeMt and AlMt). This suggests that functional groups of Fe-OH and Al-OH in FeMt and AlMt reduced the available sorption sites for atrazine by making complexes with citrate ions while forming FeMtCt and AlMtCt. The atrazine was sorbed through the hydrophobic interactions with organic compound surfaces as well as through H-bonding and ionic bonding with clay-mineral surfaces.

The important characteristics of soil organic matter affecting 2,4-dichlorophenoxyacetic acid sorption along a catenary sequence.

Variations in the characteristics of soil organic matter (SOM) at the field-scale are largely unknown, particularly in relation to observed variations in herbicide sorption. For the herbicide 2,4-D [2,4-dichlorophenoxyacetic acid], we found that its organic carbon-normalized sorption coefficient, Koc, varied by four-fold, from 76 to 315 L kg−1, in the Ap-horizon along a slope transect in an undulating agricultural field in Manitoba, Canada. In order to explain the relatively large in-field variation in 2,4-D Koc values, techniques ranging from conventional chemical fractionation methods to solid state Cross Polarization and Magic-Angle Spinning 13C-Nuclear Magnetic Resonance applied on whole soils, were used to derive SOM chemical, physical and structural parameters for correlation analyses with the measured 2,4-D Koc values on whole soils. Out of the 15 parameters considered, the 2,4-D Koc was significantly positively correlated with 1) the carbon (C) content of sodium hydroxide-extracted humic acids (r = 0.83, P < 0.01), a chemical parameter indicative of free form C in soil; 2) the molar absorptivity of humic acids at wavelength 280 nm (r = 0.81, P < 0.01), a physical parameter indicative of greater SOM aromaticity; and 3) the relatively intensity of aryl C (r = 0.92, P < 0.01) and O-aryl C (r = 0.93, P < 0.01) in whole soil, both structural parameters indicative of aromatic C. Consequently, the results suggest that in-field variations in 2,4-D Koc values are induced by variations in SOM aromaticity. Koc values are among the most sensitive parameters in herbicide fate models used in regulatory and environmental assessments. Currently, these herbicide fate models do not consider associations between SOM characteristics and Koc and hence revising model equations to include these associations may improve estimates of herbicide persistence, bioavailability and transport at the field-scale.

Effect of Rate of Copper Application on Yield of Hard Red Spring Wheat

Abstract Broadcast and incorporation of CuSO4·5H2O at a minimum rate of 4 kg Cu ha−1 is a recommended method of correcting Cu deficiency in prairie soils. Very little research has been carried out to ascertain whether near maximum yields can be obtained with lower Cu rates, especially because the cost of this practice is normally very high. Furthermore, no research has been carried out to examine the impact of overapplication of this product. Two experiments were carried out in 1999 and 2000 to address these two issues, one with 4 rates of Cu (0, 1, 2, and 4 kg Cu ha−1) and one with 12 rates (0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 kg Cu ha−1) in the form of CuSO4·H2O. A total of 16 trials were carried out with hard red spring wheat on two groups of soils, namely, one containing soils that are considered Cu deficient (<0.4 mg DTPA-Cu kg−1) and one sufficient (>0.4 mg DTPA-Cu kg−1). There was a significant wheat seed yield increase to Cu fertilization in deficient soils only with the application of up to 5 kg Cu ha−1. Near maximum yields were obtained with application of 2 kg Cu ha−1, thus providing a more economic alternative to prairie producers. Application of rates greater than 5 kg Cu ha−1 led to a gradual yield reduction and at 10 kg Cu ha−1 as CuSO4·5H2O, the yield was actually lower than that of the control. Hence, overfertilization with CuSO4·5H2O results not only in an economic waste but a danger of toxicity.

Changes in the Chemical and Mineralogical Properties of Mt. Talang Volcanic Ash in West Sumatra during the Initial Weathering Phase

Eruptions from Talang volcano on 12 April 2005 distributed volcanic ash over portions of the Solok District of West Sumatra, Indonesia. Unleached and leached pristine volcanic ash were collected immediately after the eruption, and the third sample was collected after 2 years. The mineralogy and chemical properties of pristine volcanic ash and volcanic ash deposits that were weathered for 2 years from the 2005 eruption of Mt. Talang, Sumatra, were studied to characterize the volcanic ash, identify the primary minerals present, and determine its chemical properties. Results showed that the volcanic ash contained 30% noncrystalline minerals (or volcanic glass); the remaining ash is composed of crystalline minerals such as labradorite, hypersthene, augite, hornblende, olivine, opaque ferromagnetic minerals, and rock fragments. Notable differences in pH values were observed as the pH tended to become more acidic from the unleached, leached, and weathered volcanic ash, but the ash did not give much response to the sodium fluoride (NaF) test. Total sulfur gradually decreased from 3.28% in unleached ash to 1.93% after 2 years. Available phosphorus (P) in the unleached volcanic ash was 68 mg kg−1, and this value was decreased by 15 % after 2 years of being exposed to the atmosphere, while phosphate retention ranged between 52.8% and 66.8%. Cation exchange capacity (CEC) was low with the value of 10 cmolc kg−1 although base saturation was high, exceeding 75%. The low acid oxalate–extractable silicon (Si), aluminum (Al), and iron (Fe) values of 0.07%, 0.25% and 1.17%, respectively, show the scarcity of secondary amorphous compounds in the ash. Total elemental analysis indicated that no differences were found in total silica oxide (SiO2) content of all samples, with a value about 56%, and this volcanic ash can be classified as basaltic andesite. We observed that removal of chemical elements by leaching was large for calcium oxide (CaO), magnesium oxide (MgO), and sodium oxide (Na2O) as the values decreased in time. Solid-state 29Si and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) studies indicated that Al occurred in both tetrahedral and octahedral forms. Silicon was not present in the tetrahedral layer. An intense peak at −92 ppm was indicative of the presence of aluminosilicates.

Initial Carbon Storage in New Tephra Layers of Mt. Talang in Sumatra as Affected by Pioneer Plants

ABSTRACT To date, no global data on carbon sequestration at the initial weathering phase of tephra deposits are available. To study carbon storage in the new volcanic deposit, tephra layers were reconstructed for a period of 46 months. The tephra samples were collected immediately after eruption of Mount (Mt.) Talang on 12 April 2005, over portions of the Solok District in West Sumatra, Indonesia. Pot experiments were filled with and without soil materials and covered with the collected tephra. The pot experiments were conducted in a wired house. The tephra was applied in 0, 2.5 and 5 cm depths to simulate natural tephra deposition. Every day 250 ml of filtered water was added and allowed to percolate. Solid fraction from the tephra layer was collected and analyzed at regular intervals and primary plant succession was observed over a period of 4 years. After 2 months, blue-green algae (cyanobacteria) started to colonize the bare surface tephra layer to form an algae mat. After 16 months, the surface was transformed into a green biofilm of lichen. Vascular plants (grasses and shrubs) started to be established after 2 years. Total carbon (TC) content of the tephra layer was increased significantly from 0.19 to 1.75% or eight times higher after 46 months of incubation. Higher TC storage was found in the 2.5 cm compared to that of the 5.0 cm tephra layer, which was reconstructed above the soil, with values of 1.75 and 0.89%, respectively. On the contrary, lesser amount of TC was accumulated in the single tephra layer (without soil underneath). Between 71 and 90% of TC was considered as total organic carbon (TOC). The labile organic carbon (LOC) content in the 2.5 cm and 5.0 cm of tephra layer was found to be 0.22 and 0.77%, respectively, at the end of incubation. This experiment confirmed the potential of tephra to capture carbon from the atmosphere with the help of nonvascular plants and then by vascular plants and finally sink them in the tephra layer.

Effects of Phosphorus Form on Short-Term Solubility and Availability in Soils

A laboratory experiment was set up to compare solubility and availability of four phosphate fertilizer sources over a period of 32 d after application to soils with varying pH levels. Three soils, one acidic and two alkaline, of which one was noncalcareous and one calcareous, of similar texture and organic matter, were selected. A large number of samples treated with four phosphate products, namely, two ammonium orthophosphate (9–18–9 and 6–24–0), a polyphosphate (10–34–0), and an ammonium monophosphate (11–52–0) at rates of 100 mg phosphorus (P) kg−1 soil, and an unfertilized control were incubated for a period of 32 d. Destructive sampling at 0, 1, 2, 4, 8, 16, and 32 d was used to assess water-soluble and bicarbonate-extractable P. All treatments were replicated four times. Wide differences in soluble and bicarbonate-extractable P levels from all four products in all three soils at the onset of incubation became insignificant after 2 to 4 d of incubation, suggesting that there was no difference in P availability among these products soon after their application at the time of seeding.

Retention and nitrification of injected anhydrous NH3 as affected by soil pH

Benke, M. B., Goh, T. B., Karamanos, R., Lupwayi, N. Z. and Hao, X. 2012. Retention and nitrification of injected anhydrous NH 3 as affected by soil pH. Can. J. Soil Sci. 92: 589-598. Anhydrous ammonia is an economical and extensively used fertilizer, yet loss after injection can reduce its agronomic efficiency. A laboratory experiment was conducted to examine how soil properties affect ammonia retention and nitrification following anhydrous NH3 injection using 10 different Canadian prairie soils. Soils were also injected with atmospheric air for comparison. Following injection, soils were incubated for up to 216 h at field capacity. Among the soil properties studied [pH (1:2 water), clay, total N, and organic C contents], only pH was negatively related (R 2=0.55, n=10, 24 h incubation) to percentage injected N retained by soil. The amount of N retained by soil 24 h following injection was 92±2% (mean±SEM) when pH <6, compared with 64±2% when pH>7.5. Rate of nitrification increased (P<0.001) about 48-96 h following injection and was greater in pH>7.5 than pH<6 soils. There was no difference (P>0.05) in bacterial diversity between ammonia- and air-injected soils. The slower nitrification rates suggest that potential leaching and denitrification losses in acid soils could be smaller than in alkaline soils.