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1.
Purpose
Quarrying activities in areas with serpentinized rocks may have a negative impact on plant growth. Quarry soils generally offer hostile environments for plant growth due to their low-nutrient availability, low organic matter, and high-trace metal content.Materials and methods
In order to determine the factors that can limit plant revegetation, this study was carried out in two serpentine quarries in Galicia (NW Spain): one abandoned in 1999 and the other still active.Results and discussion
The results show that in soils developed in the abandoned quarry, the limitations for revegetation were: moderate alkaline pH (7.87–8.05), strong Ca/Mg (<1) imbalance, low N (<0.42 mg kg?1) and P (<2 mg kg?1) content, and high total heavy-metal content (Co 76–147 mg kg?1; Cr 1370–2600 mg kg?1; and Ni 1340–2040 mg kg?1). The limitations were much less intense in the soils developed in the substratum in the active quarry, which were incipient soils poorly developed and permanently affected by the quarrying activity.Conclusions
Restoration work should be geared toward establishing a stable diverse vegetation cover, including serpentinophile species, which would provide the necessary modifications to correct nutritive imbalances and improve soil quality.2.
Águeda González María del Mar Gil-Diaz María del Carmen Lobo 《Journal of Soils and Sediments》2017,17(5):1403-1412
Purpose
The objective of the study was to evaluate the tolerance of barley (Hordeum vulgare) and wheat (Triticum aestivum) in soil contaminated with different concentrations of Cd and Cr, the effect of these metals on some physiological characteristics and the biomass produced in order to assess their potential application in phytoremediation of contaminated soils.Materials and methods
A greenhouse experiment using two cultivars of barley, CB502 and Pedrezuela, and one of wheat, Albares, was conducted. The pots were watered with different concentrations of Cd or Cr during the period of plant growth. Cellular membrane damage, content and fluorescence of chlorophyll, and plant biomass were evaluated. After harvesting, the content of metals in the roots, shoots and grains was analysed as well as the available metal concentration in soil samples.Results and discussion
The results show that the Cd treatments did not significantly affect the growth and physiology of the plants, but they were affected by the Cr treatments. At the highest concentration of Cr, the decrease in chlorophyll content compared to the control was 44, 77 and 83 % for the CB502 and Pedrezuela barleys and the Albares wheat respectively. A reduction in biomass was also observed (74, 81 and 85 % respectively). The amount of Cd and Cr accumulated in the root was higher than that accumulated in the aerial part for the three cultivars. The barleys accumulated the highest amount of metal in the roots. The transfer factor was lower in barley than in the wheat for both metals.Conclusions
Cadmium treatments do not affect plant development. In the case of Cr, plant development and physiological traits were significantly affected. For the highest concentration of Cr, the CB502 barley had the highest tolerance index, 26 %, and the Albares wheat had the lowest one, 15 %. The two barleys were more effective in phytoremediation of soil contaminated with Cd or Cr than the wheat, presenting a higher tolerance to these metals in the assayed conditions.3.
Purpose
Acid sulfate soils (ASS) are common in wetlands and can pose an environmental threat when they dry because oxidation of pyrite may cause strong acidification. Addition of organic matter can stimulate sulfate reduction during wet periods and minimize acidification during dry periods. However, the effect of the organic amendment may depend on its composition.Materials and methods
Three wetland acid sulfate (sulfuric, hypersulfidic, and hyposulfidic) soils collected from different depth in one profile were used. The soils, unamended or amended with 10 g C kg?1 as glucose, wheat straw, pea straw, or Phragmites litter, were incubated for 18 weeks under flooded conditions (“wet period”) followed by 10 weeks during which the soils were maintained at 100 % of maximum water-holding capacity (“dry period”).Results and discussion
During the wet period, the pH decreased in the control and with glucose to pH 3–4, but increased or was maintained in residue-amended soils (pH at the end of the wet period about 7). In the dry period, the pH of the control and glucose-amended soils remained low, whereas the pH in residue-amended soils decreased. However, at end of the dry period, the pH was higher in residue-amended soils than in the control or glucose-amended soils, particularly with pea straw (C/N 50).Conclusions
Amendment of acid sulfate soils with plant residues (particularly those with low to moderate C/N ratio) can stimulate pH increase during flooding and reduce acidification under oxidizing conditions.4.
Maria G. Chernysheva Ivan Yu. Myasnikov Gennadii A. Badun Dmitry N. Matorin Dilara T. Gabbasova Andrey I. Konstantinov Viktor I. Korobkov Natalia A. Kulikova 《Journal of Soils and Sediments》2018,18(4):1335-1346
Purpose
Detonation synthesis nanodiamonds (ND) are among the most widely applied nanoparticles due to their low cost of production and broad scope of applications. However, the fate and behavior of NDs in the environment are largely unknown. The behavior of NDs is greatly affected by humic substances (HSs), which comprise 50 to 80 % of natural organic matter in water and soil ecosystems. The uptake of detonation NDs by wheat seedlings and its toxicity were evaluated in the presence of seven HSs of different origins, including humic acids (HA, HS fraction soluble in alkali and insoluble in acid) and fulvic acids (FA, soluble in both alkali and acid).Materials and methods
To monitor the uptake of NDs by plants, tritium-labeled NDs were produced. Liquid scintillation spectrometry and autoradiography were used to determine the amount of NDs absorbed by plants. The photosynthetic activity of the plants was measured using light response curves.Results and discussion
After a 24-h exposure period, the ND content in the plant roots was 1720 μg g?1. The introduction of HSs decreased the ND contents in the plant roots to 680–1570 μg g?1 (except for peat FA, for which the ND content did not differ from the blank value). The observed phenomenon was probably related mainly to the influence of HSs on the zeta potential of the NDs, which shifted from positive to negative. Based on chlorophyll fluorescence evaluation, the toxicity of NDs did not inhibit photosynthesis during illumination in the physiological range. However, NDs were slightly toxic to wheat plants under excessive light, likely due to the inhibition of electron transport between Q A and Q B and the disruption of the formation of a thylakoid transmembrane potential.Conclusions
The introduction of HA in a suspension of NDs obviously reduced the inhibiting effect of the NDs; however, the mitigating activities of FA were not so apparent. Our results demonstrate the urgent need for further studies of the influences of NDs on plant growth and development.5.
Bashar Qasim Mikael Motelica-Heino Sylvain Bourgerie Arnaud Gauthier Domenico Morabito 《Journal of Soils and Sediments》2016,16(3):811-820
Purpose
This study aimed at investigating the rhizosphere effects of Populus euramericana Dorskamp on the mobility of Zn, Pb and Cd in contaminated technosols from a former smelting site.Materials and methods
A rhizobox experiment was conducted with poplars, where the plant stem cuttings were grown in contaminated technosols for 2 months under glasshouse conditions. After plant growth, rhizosphere and bulk soil pore water (SPW) were sampled together. SPW properties such as pH, dissolved organic carbon (DOC) and total dissolved concentrations of Zn, Pb and Cd were determined. The concentrations of Zn, Pb and Cd in plant organs were also determined.Results and discussion
Rhizosphere SPW pH increased for all studied soils by 0.3 to 0.6 units compared to bulk soils. A significant increase was also observed for DOC concentrations regardless of the soil type or total metal concentrations, which might be attributed to the plant root activity. For all studied soils, the rhizosphere SPW metal concentrations decreased significantly after plant growth compared to bulk soils which might be attributed to the increase in pH and effects of root exudates. Zn, Pb and Cd accumulated in plant organs and the higher metal concentrations were found in plant roots compared to plant shoots.Conclusions
The restricted transfer of the studied metals to the plant shoots confirms the potential role of this species in the immobilization of these metals. Thus, P. euramericana Dorskamp can be used for phytostabilization of technosols.6.
Purpose
The study aimed at comparing the effects of different water managements on soil Cd immobilization using palygorskite, which was significant for the selection of reasonable water condition.Materials and methods
Field experiment was taken to discuss the in situ remediation effects of palygorskite on Cd-polluted paddy soils, under different water managements, using a series of variables, including pH and extractable Cd in soils, plant Cd, enzyme activity, and microorganism number in soils.Results and discussion
In control group, the pH in continuous flooding was the highest under three water conditions, and compared to conventional irrigation, continuous flooding reduced brown rice Cd by 37.9%, and brown rice Cd in wetting irrigation increased by 31.0%. In palygorskite treated soils, at concentrations of 5, 10, and 15 g kg?1, brown rice Cd reduced by 16.7, 44.4, and 55.6%; 13.8, 34.5, and 44.8%; and 13.1, 36.8, and 47.3% under continuous flooding, conventional irrigation, and wetting irrigation (p < 0.05), respectively. The enzyme activity and microbial number increased after applying palygorskite to paddy soils.Conclusions
Continuous flooding was a good candidate as water management for soil Cd stabilization using palygorskite. Rise in soil enzyme activity and microbial number proved that ecological function regained after palygorskite application.7.
Elizabeth J. Lam María E. Gálvez Manuel Cánovas Ítalo L. Montofré Brian F. Keith 《Journal of Soils and Sediments》2018,18(6):2203-2216
Purpose
The objective of this work was to identify hyperaccumulator plants and evaluate their capacity on copper mine tailings in the Antofagasta Region (Chile), considered one of the most arid in the world.Materials and methods
Two native plant species, Gazania rigens and Pelargonium hortorum, were grown during 11 weeks on mine tailings. The physico-chemical characterization of the mine tailings under study indicated that the substrate required conditioning to support a phytoremediation system. In this respect, organic and inorganic amendments and mycorrizhal fungi were added to the substrate. Three treatments were designed to assess the effects of the amendments through an analysis of variance.Results and discussion
Indicators of plant growth and development were measured weekly, and concentrations of Cd, Cu, Fe, Mn, Pb, Al, and Zn in roots of tailing-grown plants and substrate were measured at the end of the experiment.Conclusions
The results were used to determine the bioconcentration factor (BCF), which demonstrated that both species act as excluders of Fe, Mn, Pb, Al, and Zn. In addition, it was found that both species present characteristics of potential accumulators of Cu.8.
Manuel M. Jordán Beatriz Rincón-Mora María Belén Almendro-Candel 《Journal of Soils and Sediments》2016,16(4):1176-1182
Purpose
Contamination of soils by potentially toxic elements (e.g. Cd, Ni, Cr, Pb) from amendments of biosolids is subject to strict controls within the European Union. Today, the use of biosolids to improve the nutrient content in a soil is a common practice. The present research was conducted to determine electrical conductivity in biosolid pellets (dry wastes) using an innovative methodology. On the other hand, the present study was designed to examine the partition of selected heavy metals in biosolid pellets and also to relate the distribution patterns of these metals.Materials and methods
In this context, heavy metal concentrations were studied in biosolid pellets under different pressures. Electrical conductivity measurements were taken in biosolid pellets under pressures on the order of 50 to 150 MPa and with currents of 10?15 A. Measurements of electrical conductivity and heavy metal content for different areas (H1, H2, and H3) were taken. Total content of metals was determined following microwave digestion and analysed by inductively coupled plasma mass spectrometry (ICP/MS). Triplicate portions were weighed in polycarbonate centrifuge tubes and sequentially extracted.Results and discussion
The distribution of chemical forms of Cd, Ni, Cr, and Pb in the biosolids was studied using a sequential extraction procedure that fractionates the metal into soluble-exchangeable, specifically sorbed-carbonate-bound, oxidizable, reducible, and residual forms. The residual, reducible, and carbonate-sorbed forms were dominant. Higher Cr and Ni content were detected in pellets made with biosolids from the H3 horizon. The highest Cd and Ni values were detected in the H2 horizon.Conclusions
The trends of the conductivity curves were similar for the sludge from the isolation surface horizon (H1) and for the horizon in the mesophilous area (H2). In the case of the horizon in the thermophilous area (H3), the electrical conductivity showed extremely high values. This behaviour was similar in the case of the Cr and Ni content. However, in the case of Cd and Pb, the highest values were detected in the H2 horizon. This experiment could be useful for establishing a general rule for taking measurements of electrical conductivity and heavy metals in biosolid pellets and other types of dry wastes.9.
Dominika Chmolowska Natnael Hamda Ryszard Laskowski 《Journal of Soils and Sediments》2017,17(2):299-305
Purpose
The study aimed at comparing organic matter decomposition in two semi-natural agrobiocenozes, namely fallows and meadows, with similar plant biomass but differing in plant community composition and diversity and in succession stage.Materials and methods
The decomposition rate of a standard material (cellulose) was measured in soils from six fallows and six meadows spanning a few kilometres apart. The mathematical model was fitted to the data.Results and discussion
The model showed a significantly longer lag-time in cellulose decomposition in the meadows. Despite the delayed start of decomposition in the meadows, the estimated decomposition rates were similar in both ecosystem types, once the decay started.Conclusions
The faster start of decomposition in fallows seems to be promoted by higher contents of nitrates and phosphates in the fallow soils. The fallows, as younger ecosystems, may have faster C turnover than older grasslands due to remains of fertilisers on these ex-arable fields.10.
Purpose
The aim of this study was to evaluate the role of phosphine in the mobilization of phosphorus in the rhizosphere soil of rice seedlings and to determine the relative efficiency of phosphine in plant P acquisition.Materials and methods
An indoor simulation experiment was conducted and the matrix-bound phosphine (MBP), phosphorus fractions, and phosphatase activity in the rhizosphere soil samples from rice cultivation, biomass, the plant P, and the root system activity were measured under different phosphine concentrations (0, 1.4, 4.2, and 7.0 mg m?3) for a period of 30 days.Results and discussion
The results indicated that phosphine treatments enhanced MBP, inorganic P (resin–Pi, NaHCO3–Pi, and NaOH–Pi), and phosphatase activity, as well as the root system activity, and the content of P in the rice seedlings was stimulated with increasing phosphine concentrations. However, organic P (NaHCO3–Po and NaOH–Po) accumulation occurred in the rhizosphere of the rice seedlings. In addition, the content of organic P in the soil samples decreased with increased phosphine concentration.Conclusions
Therefore, relatively high concentrations of phosphine in paddy field could have a positive impact on the effectiveness of phosphorus in rice plants via influencing the rhizosphere properties.11.
Yao Feng Chaojun Wei Wenjuan Zhang Yuanwang Liu Zhaojun Li Haiyan Hu Jianming Xue Murray Davis 《Journal of Soils and Sediments》2016,16(9):2242-2251
Purpose
A simple and highly efficient economic method for the analysis of 11 antibacterial drugs including two tetracyclines, three quinolones, four sulfonamides, chloramphenicol and tylosin, in livestock manure, was developed using solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC).Materials and methods
The analytes were successively extracted by EDTA-McIlvaine solution and organic solvent mixture. The extracts were degreased with n-hexane and cleaned through SPE on a hydrophile-lipophile balance (HLB) cartridge. All compounds were determined on a C18 reverse phase column with gradient elution.Results and discussion
Recoveries calculated from spiked samples of animal manures ranged from 62.65 to 99.16 % for 11 antibiotics with relative standard deviations of less than 10.0 %. Limits of detection ranged from 0.1 to 1.9 μg kg?1, and limits of quantification ranged from 0.3 to 5.9 μg kg?1.Conclusions
The results show that SPE-HPLC is an inexpensive and practical method for rapid detection of multiple antibiotics in animal manure.12.
Mahdi Safaei Khorram Yuan Zheng Dunli Lin Qian Zhang Hua Fang Yunlong Yu 《Journal of Soils and Sediments》2016,16(10):2439-2448
Purpose
Biochar application has been shown to be effective in improving soil fertility and sequestering soil contaminants. However, the impact of biochar amendments on the environmental fate of pesticides and the bioavailability of pesticides to living organisms in the soil environment is still not fully understood.Materials and methods
Dissipation of fomesafen and its bioavailability to corn (Zea mays L.) and the earthworm Eisenia fetida in an agricultural soil amended with three different rates of rice hull biochar (0.5, 1, and 2 % (w/w)) under laboratory conditions was investigated.Results and discussion
Biochar amendment significantly increased the DT50 of fomesafen from 34 days in unamended soil to 160 days in 2 % biochar-amended soil. Furthermore, biochar amendment decreased fomesafen concentration in soil pore water resulting in lower plant uptake of the pesticide. In this case, total plant residue and soil pore water concentrations of fomesafen in 2 % biochar-amended soil decreased to 0.29 % and 0.28–45 % of that in the control, respectively. Similar results were obtained for bioavailability of fomesafen in earthworms, as the earthworm residue and soil pore water concentration of fomesafen in 2 % biochar-amended soil declined to 0.38–45 and 0.47–0.50 % compared to the level of the control, respectively.Conclusions
As biochar could markedly reduce the concentration of fomesafen in soil pore water and subsequently reduce plant and earthworm uptake of fomesafen from contaminated soil, biochar amendment could be considered an appropriate option for immobilizing fomesafen in soils, protecting nontarget organisms from fomesafen contamination.13.
Purpose
The Al forms on maize and soybean roots were investigated to determine the main factors affecting the distribution of Al forms and its relationship with Al plant toxicity.Materials and methods
Solution culture experiments were conducted to obtain the fresh roots of maize and soybean. KNO3, citric acid, and HCl were used to extract the exchangeable, complexed, and precipitated forms of Al on the roots.Results and discussion
The complexed Al was higher than the exchangeable and precipitated Al. Root CECs of soybean and maize were 77 and 55 cmol kg?1, and functional groups on the soybean roots (262.4 cmol kg?1) were greater than on maize roots (210.8 cmol kg?1), which resulted in more exchangeable and complexed Al on soybean roots than on maize roots, and was one of the reasons for the increased Al toxicity to soybean. The total and exchangeable Al were the highest on the plant root tips and decreased gradually with increasing distance from the tips. Ca2+, Mg2+, and NH4 + cations reduced the exchangeable Al on the roots. Oxalate and malate also reduced the adsorption and absorption of Al by roots, and the effect of oxalate was greater than malate.Conclusions
Higher exchangeable and complexed Al on plant roots led to increased Al plant toxicity. Ca2+, Mg2+, and NH4 + and oxalate and malate can effectively alleviate Al plant toxicity.14.
Javier M. Gonzalez Douglas R. Smith Stan Livingston Elizabeth Warnemuende-Pappas Martha Zwonitzer 《Journal of Soils and Sediments》2016,16(7):1921-1932
Purpose
In a 6-year study, we investigated the effectiveness of blind inlets as a conservation practice in reducing pesticide losses compared to tile risers from two closed farmed depressional areas (potholes) in the US Midwest under a 4-year cropping rotation.Materials and methods
In two adjacent potholes within the same farm and having similar soils, a conventional tile riser and blind inlet were installed. Each draining practice could be operated independent of each other in order to drain and monitor each depression with either practice. Sampling events (runoff events) were collected from the potholes from 2008 to 2013 using autosamplers. The samples were analyzed for atrazine, metolachlor, 2,4-D, glyphosate, and deethylatrazine.Results and discussion
The results of this study demonstrated that the blind inlet reduced analyzed pesticide losses; however, the level of reduction was compound dependent: atrazine (57 %), 2,4-D (58 %), metolachlor (53 %), and glyphosate (11 %).Conclusions
Results from this study corroborate previous research findings that blind inlets are an effective conservation practice to reduce discharge and pollutants, including pesticides from farmed pothole surface runoff in the US Midwest.15.
Purpose
Studying the rate of chelant degradation is important to select environmental friendly compounds to assist phytoextraction. The objective of the present study was to evaluate degradation rate of complexes formed between synthetic or organic chelants and Pb aiming to increase the efficiency of phytoextraction while reducing adverse effects resulting from the Pb leaching.Materials and methods
The following six chelating agents were tested: citric acid P.A., commercial citric acid, glutamic acid P.A., monosodium glutamate, nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA), besides a control treatment (no addition of chelating agent); they were applied at a concentration of 10 mmol dm?3 in pots containing 1 dm3 of Pb-contaminated soil.Results and discussion
The results of this study showed that commercial citric acid adequately solubilized Pb to levels suitable for plant uptake and showed relatively rapid biodegradation in soil. Therefore, this commercial product may be a highly promising alternative for phytoextraction studies in the field. EDTA and NTA demonstrated high Pb solubilization ability but degraded comparatively slowly; therefore, they are not recommended for use in phytoextraction due to environmental risks regarding metal leaching.Conclusions
The results of this study showed that commercial citric acid adequately solubilized Pb to levels suitable for plant uptake and showed relatively rapid biodegradation in soil, which is associated with a low risk of groundwater contamination. Therefore, this environmental friendly and low-cost product may be a highly promising alternative for inducing Pb phytoextraction.16.
Thi Thu Nhan Nguyen Helen M. Wallace Cheng-Yuan Xu Zhihong Xu Michael B. Farrar Stephen Joseph Lukas Van Zwieten Shahla Hosseini Bai 《Journal of Soils and Sediments》2017,17(12):2763-2774
Purpose
Organo-mineral biochar fertiliser has the potential to replace conventional biochar and organic fertiliser to improve soil quality and increase plant photosynthesis. This study explored mechanisms involved in nitrogen (N) cycling in both soil and ginger plants (Zingiber officinale: Zingiberaceae) following different treatments including organic fertiliser, commercial bamboo biochar fertiliser, and organo-mineral biochar fertiliser.Materials and methods
Soil received four treatments including (1) commercial organic fertiliser (5 t ha?1) as the control, (2) commercial bamboo biochar fertiliser (5 t ha?1), (3) organo-mineral biochar fertiliser at a low rate (3 t ha?1), and (4) organo-mineral biochar fertiliser at a high rate (7.5 t ha?1). C and N fractions of soil and plant, and gas exchange measurements were analysed.Results and discussion
Initially, organo-mineral biochar fertiliser applied at the low rate increased leaf N. Organo-mineral biochar fertiliser applied at the high rate significantly increased N use efficiency (NUE) of the aboveground biomass compared with other treatments and improved photosynthesis compared with the control. There was N fractionation during plant N uptake and assimilation since the 15N enrichment between the root, leaf, and stem were significantly different from zero; however, treatments did not affect this N fractionation.Conclusions
Organo-mineral biochar fertiliser has agronomic advantages over inorganic and raw organic (manure-based) N fertiliser because it allows farmer to put high concentrations of nutrients into soil without restricting N availability, N uptake, and plant photosynthesis. We recommend applying the low rate of organo-mineral biochar fertiliser as a substitute for commercial organic fertiliser.17.
Jianqing Wang Xuhui Zhang Lianqing Li Kun Cheng Jufeng Zheng Jinwei Zheng Mingxing Shen Xiaoyu Liu Genxing Pan 《Journal of Soils and Sediments》2016,16(12):2666-2675
Purpose
Although micronutrients are essential to higher plants, it remains unclear whether the projected future climate change would affect their availability to plants. The objective of this study was to investigate the effect of carbon dioxide (CO2) enrichment and warming on soil micronutrient availability and plant uptake.Materials and methods
This study was conducted in an open field experiment with CO2 enrichment and plant canopy warming. Four treatments were included: (1) free-air CO2 enrichment up to 500 ppm (CE); (2) canopy warming by plus 2 °C (WA); (3) CO2 enrichment combined with canopy warming (CW), and (4) ambient condition as control. Plant and soil samples were collected, respectively, at the jointing, heading, and ripening stage over the whole wheat growing season in 2014. The micronutrient concentrations both in soil and plant were both analyzed, and the accumulated uptake by wheat harvest was assessed.Results and discussion
Both CO2 enrichment and warming increased the availability of most soil micronutrients. The availability of Fe, Mn, Cu, and Zn under CO2 enrichment increased by 47.7, 22.5, 59.8, and 114.1 %, respectively. Warming increased the availability of Fe, Cu, and Zn by 60.4, 23.8, and 15.3 %, respectively. The plant growth induced changes in soil pH and in soil microbial biomass carbon (MBC) accounted to the changes in soil micronutrient availability. The enrichment of CO2 and warming had significant effects on micronutrient uptake by wheat. The enrichment of CO2 decreased the concentration of Fe by 9.3 %, while it increased the concentrations of Mn and Zn by 18.9 and 8.1 % in plant shoot, respectively. Warming increased the concentration of Fe and Cu by 24.3 and 7.6 % in plant shoot, respectively. The increase in soil micronutrient availability did not always lead to the increase in micronutrient uptake. The element types and crop growth stage affected the uptake of micronutrients by wheat under CO2 enrichment and warming. Additionally, CO2 enrichment decreased the translocation of Fe and Zn by 25.3 and 10.0 %, respectively, while warming increased the translocation of Fe, Mn, Cu, and Zn across stages.Conclusions
Our results demonstrated that CO2 enrichment and warming would improve availability of some micronutrients and their uptake by wheat. However, it is still unclear whether a net removal of micronutrient through crop straw harvest would occur under CO2 enrichment and warming.18.
Xiaodong Zhang Zhaoliang Song Zhiqi Zhao Lukas Van Zwieten Jianwu Li Linan Liu Song Xu Hailong Wang 《Journal of Soils and Sediments》2017,17(2):481-490
Purpose
Occlusion of carbon (C) within phytoliths, biogenic silica deposited in plant tissues and returned to the soil, is an important mechanism for long-term terrestrial biogeochemical C sequestration and might play a significant role in mitigating climate change.Materials and methods
Subtropical and tropical soil profiles (to 100 cm depth) developed on granite and basalt were sampled using a mass-balance approach to explore the influence of climate and lithology on soil phytolith-occluded carbon (PhytOC) accumulation.Results and discussion
Soil PhytOC storage in the subtropics was significantly greater than in the tropics, with the soil profiles developed on granite storing greater PhytOC than soils derived on basalt. Phytolith and PhytOC content decreased with depth in all soil profiles. Phytolith content showed a positive correlation with the soil bio-available silicon in the soil profiles developed on basalt, while a negative correlation was observed in soil profiles developed on granite.Conclusions
Climate and lithology have a significant impact on soil PhytOC sequestration. The management of forests (e.g., afforestation and reforestation) and external silicon amendments (e.g., basalt powder amendment) in soils, especially those developed on granite, have the potential to enhance PhytOC accumulation in forest ecosystems.19.
Yasser Mahmoud Awad Sang Soo Lee Yong Sik Ok Yakov Kuzyakov 《Journal of Soils and Sediments》2017,17(3):611-620
Purpose
Various soil conditioners, such as biochar (BC) and anionic polyacrylamide (PAM), improve soil fertility and susceptibility to erosion, and may alter microbial accessibility and decomposition of soil organic matter (SOM) and plant residues. To date, no attempts have been made to study the effects of BC in combination with PAM on the decomposition of soil SOM and plant residues. The objective of this study was to evaluate the effects of BC, PAM, and their combination on the decomposition of SOM and alfalfa residues.Materials and methods
An 80-day incubation experiment was carried out to investigate the effects of oak wood biochar (BC; 10 Mg ha?1), PAM (80 kg ha?1), and their combination (BC?+?PAM) on decomposition of SOM and 14C-labeled alfalfa (Medicago sativa L.) residues by measuring CO2 efflux, microbial biomass, and specific respiration activity.Results and discussion
No conditioner exerted a significant effect on SOM decomposition over the 80 days of incubation. PAM increased cumulative CO2 efflux at 55–80 days of incubation on average of 6.7 % compared to the soil with plant residue. This was confirmed by the increased MBN and MB14C at 80 days of incubation in PAM-treated soil with plant residue compared to the control. In contrast, BC and BC?+?PAM decreased plant residue decomposition compared to that in PAM-treated soil and the respective control soil during the 80 days. BC and BC?+?PAM decreased MBC in soil at 2 days of incubation indicated that BC suppressed soil microorganisms and, therefore, decreased the decomposition of plant residue.Conclusions
The addition of oak wood BC alone or in combination with PAM to soil decreased the decomposition of plant residue.20.
Jiali Yin Zicheng Zheng Tingxuan Li Xizhou Zhang Shuqin He Yongdong Wang Haiying Yu Tao Liu 《Journal of Soils and Sediments》2016,16(8):2128-2137