Generally,nanotechnology plays an very important role in various applied scientific fields.Iron and magnesium nanoparticles(NPs)can cause positive or negative changes in soil physical and mechanical properties,especia...Generally,nanotechnology plays an very important role in various applied scientific fields.Iron and magnesium nanoparticles(NPs)can cause positive or negative changes in soil physical and mechanical properties,especially in long periods.The aim of this study was to investigate the multi-year effects of NPs on soil water retention and aggregate tensile strength.A wheat farm loamy soil was amended with 1%,3%,and 5%(weight/weight)of magnesium oxide(Mg O)and iron oxide(Fe_(3)O_(4))NPs in three replications and incubated for three years.Water contents were measured at different matric suctions of 0,10,20,40,60,100,300,1000,and 15000 cm.The van Genuchten model was fitted to the moisture data.Tensile strength was measured on the 2–4 mm aggregates at matric suctions of 300(i.e.,field capacity)and 15000(i.e.,permanent wilting point)cm.The results showed that the levels of 1%and 3%Fe_(3)O_(4)NPs significantly increased water retention,compared to the no NP application control and 5%Mg O NPs,which is probably due to the increase of adsorption surfaces in the treated soils.Water contents at field capacity and permanent wilting point in the 5%Mg O NP treatment decreased compared to those of the other treatments,due to the increased soil vulnerability and reduced soil fine pores.The application of Fe_(3)O_(4)NPs did not have any significant effect on soil tensile strength.Based on the results of this study,soil physical and mechanical properties could be affected by NP application.展开更多
Soil water retention data are essential for irrigation scheduling and determination of irrigation frequency. However, direct measurement of this characteristic is time consuming and expensive and furthermore its spati...Soil water retention data are essential for irrigation scheduling and determination of irrigation frequency. However, direct measurement of this characteristic is time consuming and expensive and furthermore its spatial and temporal variabilities in field scales increase the number of measurements. Different pedotransfer functions, such as Saxton et al., Campbell, Vereecken et al., l^awls and Brakensiek, WSsten et al., Rajkni et al., Ghorbani Dashtaki and Homaee, Zacharias and Wessolek, and Rosetta, were evaluated to estimate soil water retention of saline and saline-alkali soils collected from south of Tehran, Iran. The saturation-extract conductivity of all the 68 samples and exchangeable sodium percentage of more than half of them were measured to be greater than 4 dS m-1 and 15%, respectively. The calculated Akaike＇s information criterion values showed that Saxton et al. and Campbell models were the best in estimation of soil water retention curve and total available water, respectively.展开更多
Biochar as an organic amendment improves soil attributes,with a potentially significant effect on soil chemical fertility and quality.The main objective of this study was to quantify the effect of biochar addition on ...Biochar as an organic amendment improves soil attributes,with a potentially significant effect on soil chemical fertility and quality.The main objective of this study was to quantify the effect of biochar addition on nutrients,carbon sequestra-tion and microbial activity and understand the mechanisms of controlling biochar effects in calcareous soils.Maize residue biochars produced at 200,400 and 600℃ were added at 5 and 10 g kg^(−1)rates to sandy loam and clayey texture calcareous soils.The soil properties measured were pH and electrical conductivity(EC),plant-available potassium(K)and available phosphorus(P),total nitrogen(TN),C sequestration;and the fluorescein diacetate(FDA)hydrolysis activity.Addition of raw material and biochars increased pH(0.15-0.46 units),EC(0.14-0.38 dS m^(−1)),TN(63-120%),K(12-41%)and FDA activity(27-280%),but tended to decrease plant-available P(23-86%).Increasing pyrolysis temperature increased soil C pool index(CPI),but decreased the FDA and the changes depended largely upon the application rate and soil texture.The positive effects of biochar addition and its pyrolysis temperature on soil C sequestration potential were more pronounced at high than low application rate and in sandy loam than clayey soils.Nevertheless,the effect of biochar addition and pyrolysis temperature on the FDA activity was higher at high than low application rates,but lower in sandy loam than clayey soils.Although biochar application may successfully improve soil processes and attributes and have a high potential for C seques-tration,its effects are controlled by soil texture,pyrolysis temperature and application rate.展开更多
Soil β-glucosidase (BG), the rate-limiting enzyme in the final step of cellulose hydrolysis, plays a key role in microbial metabolism, carbon (C) cycling and sequestration in terrestrial ecosystems. Biochar applicati...Soil β-glucosidase (BG), the rate-limiting enzyme in the final step of cellulose hydrolysis, plays a key role in microbial metabolism, carbon (C) cycling and sequestration in terrestrial ecosystems. Biochar application is known to affect soil BG activity;however, most of the biochar studies have focused on the potential activity of BG, and it is not clear how biochar influences the kinetic and thermodynamic behavior of BG in the soil. The objective of this study was to investigate the effect of maize residue biochar on soil BG kinetic and thermodynamic parameters. Soil BG kinetic (V_(max) and K_(m)) and ther-modynamic (E_(a), ΔH_(a) and Q_(10)) parameters were determined within soils (clayey and sandy loam soils) amended with either maize residue (as positive control) or its biochar (600℃) at 0.5 and 1.0% ratios (w/w), and the mixtures were incubated for 90 days. BG showed an increase in potential enzymatic activity (81%), enzyme concentration (higher V_(max) value) (25%) and substrate affinity (lower K_(m) value) (32%) in the biochar-amended sandy loam soil only at high addition rates compared with the control, and an increase by about 86% of the catalytic efficiency (V_(max)/K_(m)). In the clayey soil, biochar addition decreased potential BG activity (by 10-29%), increased the V_(max) value (by 20-25%) and had no impact on enzyme-substrate binding affinity, but still increased the catalytic efficiency by 47-72%. Adsorption of soil BG by biochar particles did not affect the catalytic efficiency in the soil. Generally, application of maize residue biochar to the soil decreased the E_(a), ΔH_(a) and Q_(10) values of BG compared with the negative controls at both biochar rates in the light-textured soil and only at low biochar rate in heavy-textured soil. The direction and magnitude of BG responses (activity, kinetics, and thermodynamics) to biochar were more related to the soil characteristics. Biochar would increase soil BG thermal stability and decrease its sensitivity to increasing temperature and global warming.展开更多
Soil amendment with biochar alleviates the toxic effects of heavy metals on microbial functions in single-metal contaminated soils.Yet,it is unclear how biochar application would improve microbial activity and enzymat...Soil amendment with biochar alleviates the toxic effects of heavy metals on microbial functions in single-metal contaminated soils.Yet,it is unclear how biochar application would improve microbial activity and enzymatic activity in soils co-polluted with toxic metals.The present research aimed at determining the response of microbial and biochemical attributes to addition of sugarcane bagasse biochar(SCB)in cadmium(Cd)-lead(Pb)co-contaminated soils.SCBs(400 and 600°C)decreased the available concentrations of Cd and Pb,increased organic carbon(OC)and dissolved organic carbon(DOC)contents in soil.The decrease of metal availability was greater with 600°C SCB than with 400°C SCB,and metal immobilization was greater for Cd(16%)than for Pb(12%)in co-spiked soils amended with low-temperature SCB.Biochar application improved microbial activity and biomass,and enzymatic activity in the soils co-spiked with metals,but these positive impacts of SCB were less pronounced in the co-spiked soils than in the single-spiked soils.SCB decreased the adverse impacts of heavy metals on soil properties largely through the enhanced labile C for microbial assimilation and partly through the immobili-zation of metals.Redundancy analysis further confirmed that soil OC was overwhelmingly the dominant driver of changes in the properties and quality of contaminated soils amended with SCB.The promotion of soil microbial quality by the low-temperature SCB was greater than by high-temperature SCB,due to its higher labile C fraction.Our findings showed that SCB at lower temperatures could be applied to metal co-polluted soils to mitigate the combined effects of metal stresses on microbial and biochemical functions.展开更多
Processing improves the visual quality of food;however,the ingredient and nutritional values may alter.In present study,the sugar samples(refined,raw,gur(Jaggery/jaggeree)and molasses)were collected from 20 different ...Processing improves the visual quality of food;however,the ingredient and nutritional values may alter.In present study,the sugar samples(refined,raw,gur(Jaggery/jaggeree)and molasses)were collected from 20 different agro-climatic regions of Pakistan and analyzed for the chromium concentration,total phenolic and antioxidant activity,in order to evaluate the processing effect.The concentration of Cr was determined by digestion method using atomic absorption spectrophotometer,while antioxidant activity was determined by DPPH(1,1-diphenyl-2-picrylhydrazyl)and reducing power.It was observed that chromium content in Jaggery was 74%higher than raw sugar,while molasses showed 21.27%higher concentration versus jaggery.The total phenolic contents were found considerably higher in molasses(3751 lg GAE/g)followed by Jaggery(3285 lg GAE/g),raw sugar(27.75 lg GAE/g)and refined sugar(23.81 lg GAE/g).The DPPH scavenging activity and reducing power was also found dependent to sugar type.Form results,it can be concluded that processing significantly affected the chromium contents,total phenolics and antioxidant activity.展开更多
文摘Generally,nanotechnology plays an very important role in various applied scientific fields.Iron and magnesium nanoparticles(NPs)can cause positive or negative changes in soil physical and mechanical properties,especially in long periods.The aim of this study was to investigate the multi-year effects of NPs on soil water retention and aggregate tensile strength.A wheat farm loamy soil was amended with 1%,3%,and 5%(weight/weight)of magnesium oxide(Mg O)and iron oxide(Fe_(3)O_(4))NPs in three replications and incubated for three years.Water contents were measured at different matric suctions of 0,10,20,40,60,100,300,1000,and 15000 cm.The van Genuchten model was fitted to the moisture data.Tensile strength was measured on the 2–4 mm aggregates at matric suctions of 300(i.e.,field capacity)and 15000(i.e.,permanent wilting point)cm.The results showed that the levels of 1%and 3%Fe_(3)O_(4)NPs significantly increased water retention,compared to the no NP application control and 5%Mg O NPs,which is probably due to the increase of adsorption surfaces in the treated soils.Water contents at field capacity and permanent wilting point in the 5%Mg O NP treatment decreased compared to those of the other treatments,due to the increased soil vulnerability and reduced soil fine pores.The application of Fe_(3)O_(4)NPs did not have any significant effect on soil tensile strength.Based on the results of this study,soil physical and mechanical properties could be affected by NP application.
文摘Soil water retention data are essential for irrigation scheduling and determination of irrigation frequency. However, direct measurement of this characteristic is time consuming and expensive and furthermore its spatial and temporal variabilities in field scales increase the number of measurements. Different pedotransfer functions, such as Saxton et al., Campbell, Vereecken et al., l^awls and Brakensiek, WSsten et al., Rajkni et al., Ghorbani Dashtaki and Homaee, Zacharias and Wessolek, and Rosetta, were evaluated to estimate soil water retention of saline and saline-alkali soils collected from south of Tehran, Iran. The saturation-extract conductivity of all the 68 samples and exchangeable sodium percentage of more than half of them were measured to be greater than 4 dS m-1 and 15%, respectively. The calculated Akaike＇s information criterion values showed that Saxton et al. and Campbell models were the best in estimation of soil water retention curve and total available water, respectively.
基金We express our thanks to Shahrekord University for providing the financial support under the grant of 93GCU2M1932。
文摘Biochar as an organic amendment improves soil attributes,with a potentially significant effect on soil chemical fertility and quality.The main objective of this study was to quantify the effect of biochar addition on nutrients,carbon sequestra-tion and microbial activity and understand the mechanisms of controlling biochar effects in calcareous soils.Maize residue biochars produced at 200,400 and 600℃ were added at 5 and 10 g kg^(−1)rates to sandy loam and clayey texture calcareous soils.The soil properties measured were pH and electrical conductivity(EC),plant-available potassium(K)and available phosphorus(P),total nitrogen(TN),C sequestration;and the fluorescein diacetate(FDA)hydrolysis activity.Addition of raw material and biochars increased pH(0.15-0.46 units),EC(0.14-0.38 dS m^(−1)),TN(63-120%),K(12-41%)and FDA activity(27-280%),but tended to decrease plant-available P(23-86%).Increasing pyrolysis temperature increased soil C pool index(CPI),but decreased the FDA and the changes depended largely upon the application rate and soil texture.The positive effects of biochar addition and its pyrolysis temperature on soil C sequestration potential were more pronounced at high than low application rate and in sandy loam than clayey soils.Nevertheless,the effect of biochar addition and pyrolysis temperature on the FDA activity was higher at high than low application rates,but lower in sandy loam than clayey soils.Although biochar application may successfully improve soil processes and attributes and have a high potential for C seques-tration,its effects are controlled by soil texture,pyrolysis temperature and application rate.
基金The research described in this article has been funded wholly by a joint grant from Shahrekord University(Grant nos:93GCU2M1932 and 95GRN1M1932)。
文摘Soil β-glucosidase (BG), the rate-limiting enzyme in the final step of cellulose hydrolysis, plays a key role in microbial metabolism, carbon (C) cycling and sequestration in terrestrial ecosystems. Biochar application is known to affect soil BG activity;however, most of the biochar studies have focused on the potential activity of BG, and it is not clear how biochar influences the kinetic and thermodynamic behavior of BG in the soil. The objective of this study was to investigate the effect of maize residue biochar on soil BG kinetic and thermodynamic parameters. Soil BG kinetic (V_(max) and K_(m)) and ther-modynamic (E_(a), ΔH_(a) and Q_(10)) parameters were determined within soils (clayey and sandy loam soils) amended with either maize residue (as positive control) or its biochar (600℃) at 0.5 and 1.0% ratios (w/w), and the mixtures were incubated for 90 days. BG showed an increase in potential enzymatic activity (81%), enzyme concentration (higher V_(max) value) (25%) and substrate affinity (lower K_(m) value) (32%) in the biochar-amended sandy loam soil only at high addition rates compared with the control, and an increase by about 86% of the catalytic efficiency (V_(max)/K_(m)). In the clayey soil, biochar addition decreased potential BG activity (by 10-29%), increased the V_(max) value (by 20-25%) and had no impact on enzyme-substrate binding affinity, but still increased the catalytic efficiency by 47-72%. Adsorption of soil BG by biochar particles did not affect the catalytic efficiency in the soil. Generally, application of maize residue biochar to the soil decreased the E_(a), ΔH_(a) and Q_(10) values of BG compared with the negative controls at both biochar rates in the light-textured soil and only at low biochar rate in heavy-textured soil. The direction and magnitude of BG responses (activity, kinetics, and thermodynamics) to biochar were more related to the soil characteristics. Biochar would increase soil BG thermal stability and decrease its sensitivity to increasing temperature and global warming.
文摘Soil amendment with biochar alleviates the toxic effects of heavy metals on microbial functions in single-metal contaminated soils.Yet,it is unclear how biochar application would improve microbial activity and enzymatic activity in soils co-polluted with toxic metals.The present research aimed at determining the response of microbial and biochemical attributes to addition of sugarcane bagasse biochar(SCB)in cadmium(Cd)-lead(Pb)co-contaminated soils.SCBs(400 and 600°C)decreased the available concentrations of Cd and Pb,increased organic carbon(OC)and dissolved organic carbon(DOC)contents in soil.The decrease of metal availability was greater with 600°C SCB than with 400°C SCB,and metal immobilization was greater for Cd(16%)than for Pb(12%)in co-spiked soils amended with low-temperature SCB.Biochar application improved microbial activity and biomass,and enzymatic activity in the soils co-spiked with metals,but these positive impacts of SCB were less pronounced in the co-spiked soils than in the single-spiked soils.SCB decreased the adverse impacts of heavy metals on soil properties largely through the enhanced labile C for microbial assimilation and partly through the immobili-zation of metals.Redundancy analysis further confirmed that soil OC was overwhelmingly the dominant driver of changes in the properties and quality of contaminated soils amended with SCB.The promotion of soil microbial quality by the low-temperature SCB was greater than by high-temperature SCB,due to its higher labile C fraction.Our findings showed that SCB at lower temperatures could be applied to metal co-polluted soils to mitigate the combined effects of metal stresses on microbial and biochemical functions.
文摘Processing improves the visual quality of food;however,the ingredient and nutritional values may alter.In present study,the sugar samples(refined,raw,gur(Jaggery/jaggeree)and molasses)were collected from 20 different agro-climatic regions of Pakistan and analyzed for the chromium concentration,total phenolic and antioxidant activity,in order to evaluate the processing effect.The concentration of Cr was determined by digestion method using atomic absorption spectrophotometer,while antioxidant activity was determined by DPPH(1,1-diphenyl-2-picrylhydrazyl)and reducing power.It was observed that chromium content in Jaggery was 74%higher than raw sugar,while molasses showed 21.27%higher concentration versus jaggery.The total phenolic contents were found considerably higher in molasses(3751 lg GAE/g)followed by Jaggery(3285 lg GAE/g),raw sugar(27.75 lg GAE/g)and refined sugar(23.81 lg GAE/g).The DPPH scavenging activity and reducing power was also found dependent to sugar type.Form results,it can be concluded that processing significantly affected the chromium contents,total phenolics and antioxidant activity.
