Some Inceptisols representing the Singla catchment area in Karimgaungedistrict of Assam, India, were studied for lime requirement as influenced by the nature of soilacidity. The electrostatically bonded (EB)-H^+ and E...Some Inceptisols representing the Singla catchment area in Karimgaungedistrict of Assam, India, were studied for lime requirement as influenced by the nature of soilacidity. The electrostatically bonded (EB)-H^+ and EB-Al^(3+) acidities constituted 33 and 67percent of exchangeable acidity while EB-H^+, EB-Al^(3+), exchangeable and pH-dependent aciditiescomprised 6, 14, 20 and 80 percent of total potential acidity. The pH-dependent acidity made a majorcontribution towards the total potential acidity (67%～84%). Grand mean of lime requirementdetermined by the laboratory incubation method and estimated by the methods of New Woodruff,Woodruff and Peech as expressed in MgCaCO_3 ha^(-1) was in the order: Woodruff (15.6) > New Woodruff(14.9) > Peech (5.1) > incubation (5.0). Correlations analysis among different forms of acidity andlime requirement methods with selected soil properties showed that pH in three media, namely water,1 mol L^(-1) KC1 and 0.01 mol L^(-1) CaCl_2, had a significant negative correlation with differentforms of acidity and lime requirement methods. Exchangeable Fe and Al showed significant positivecorrelations with EB-Al^(3+) acidity, exchangeable acidity, pH-dependent acidity and total potentialacidity, and also lime requirement methods. Extractable Al showed positive correlations withdifferent forms of acidity except EB-H^+ and EB-Al^(3+) acidities. The lime requirement by differentmethods depended upon the extractable aluminium. Significant positive correlations existed betweenlime requirements and different forms of acidity of the soils except EB-H^+ acidity and incubationmethod. The nature of soil acidity was mostly pH-dependent. Statistically, the Woodruff method didslightly better than the New Woodruff, incubation and Peech methods at estimating lime requirementand hence the Woodruff procedure may be recommended for routine soil testing because of its speedand simplicity.展开更多
Two Inceptisols and an Alfisol of the Indravati Catchment area in Chattisgarh, India, comprising several gradientsin physical and chemical properties were studied to relate phosphate sorption and desorption to soil pr...Two Inceptisols and an Alfisol of the Indravati Catchment area in Chattisgarh, India, comprising several gradientsin physical and chemical properties were studied to relate phosphate sorption and desorption to soil properties. Fromthe P isotherm curve, the standard P requirement (SPR) of the soils was determined. Phosphate sorption data were alsofitted both to the Langmuir and Freundlich Equations. The mean sorption maximum values for three different soil serieswere: Bastar > Geedam > Mosodi. The fraction of added phosphate sorbed for the 3 series followed this same trend asdid SPR; the phosphate sorption maximum and the maximum phosphate buffering capacity, which were estimated by theLangmuir isotherm; and the Freundlich constant 1/n. However, phosphate desorption, as well as the maximum recoverypercent did not follow this order. The phosphate affinity constant (K) was also different following the same progressionfor the 3 soil series as the Freundlich constant K’, which measured sorption strength. Meanwhile, an inverse order existedfor K and K’ versus the percent desorbed relative to the sorbed as well as the maximum recovery percent. In addition,significant correlation coefficients among sorption parameters of P and soil factors were found.展开更多
Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley＇s extraction was used to separate soil phosphorus （P） into inorganic Pi （ge...Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley＇s extraction was used to separate soil phosphorus （P） into inorganic Pi （geochemical） and organic Po （biological） fractions. Direct extractable P by Olsen （Olsen-P）, by Mehlich llI （M3-P） and by ammonium oxalate （Pox） was also determined. Phosphorus sorption was carried out with 1：10 soil/solution ratio and sorption parameters were derived from the Langmuir model to the experimental data. Most of the total P occurred in inorganic P forms （74% of Pt）, while organic P comprised only 26% of the Pt. Among the various inorganic P forms relatively large amount of residual P （111 mg kg^-1） was observed, while occluded P in calcium phosphate minerals （d.HCI-Pi） and in Fe, Al-oxides （c.HCI-Pi） existed in equal amounts （83.1 and 83.7 mg kg^-1 respectively）. The phosphorus sorption parameters showed positive relationships with clay content, cation exchange capacity and the sum of exchangeable calcium plus magnesium. Overall, this study indicated that Ca and Mg compounds strongly influence the P chemistry in moderately weathered soils, with relatively high concentration of primary P minerals.展开更多
Slash and burn cultivation systems carried out by many farmers in the Amazon region lead to changes in biogeochemical cycles of nutrients. To assess the extent of the impact of shifting cultivation on the soil in a fl...Slash and burn cultivation systems carried out by many farmers in the Amazon region lead to changes in biogeochemical cycles of nutrients. To assess the extent of the impact of shifting cultivation on the soil in a floodplain portion of this region, samples of an Inceptisol surface layer (0 - 5 cm) under primary forest (FP), secondary forest at an advanced stage of recovery (FS), secondary forest at an initial stage of recovery (CAP), agroforestry (SAF), plantations (R?) in indigenous communities and small farmers, and pasture (PAS) in the Upper Solim?es region, Amazonas, were subjected to analysis of chemical composition during the wet (May) and dry (October) seasons, 2007. Soils were fertile with levels of P, K, Ca and Mg above those generally found in Amazon soils. Microbial content did not vary significantly in the systems studied in the wet season, but there was a reduction of around 60% with the change of season, except for soils with SAF. Ammonium nitrogen was predominant in all systems and seasons studied. Nitrate content was higher in R? soil, in two seasons, and lower in PAS. The type of management adopted by farmers in the region’s indigenous agroforestry systems resulted in small changes in P, K, Mg, MBC and mineral-N levels, independent of soil moisture.展开更多
Quantitative weathering indices are efficient tools in determining the soil development from the underlying rocks.In order to evaluate the effects of climate on the soils developed under an arid to sub-humid climosequ...Quantitative weathering indices are efficient tools in determining the soil development from the underlying rocks.In order to evaluate the effects of climate on the soils developed under an arid to sub-humid climosequence in central Iran,twenty soil-development indices were compared.Twentyfour samples from six pedons were analyzed for routine physico-chemical and geochemical analyses using X-ray fluorescence(XRF).The lowest and highest calculated soil development indices were observed in the arid and sub-humid regions respectively.Among the studied indices,fifteen indices showed similar trends concerning the intensity of weathering.The consistency of such trends reveals the feasibility of using these indices to evaluate basalt weathering rate and soil development in arid,semi-arid and sub-humid regions.This study demonstrated that,among the evaluated weathering indices,the Weathering Index of Parker(WIP)and mass transfer coefficient(τ)were the most proper indices for predicting basalt weathering intensity.This is due to the fact that these indices use the highly mobile earth elements which are the most sensitive elements in basalt chemical weathering.The calculated indices were subdivided into three subgroups including the ratios of mobile/immobile,mobile/mobile and immobile/mobile elements based on the elements used in their calculation.The state of soil evolution was more accurately predicted compared to the other subgroups using the mobile/immobile subgroup of indices.Overall,the weathering indices calculated using the mobile elements are better indicators of weathering intensity,soil formation and the exogenous processes across the arid to sub-humid climosequence.展开更多
Agriculture under changing climate scenario is facing major challenges of water scarcity and resource imbalances.Crop water productivity(WP)may act as an indicator of crop responses to water limitation.Organic amendme...Agriculture under changing climate scenario is facing major challenges of water scarcity and resource imbalances.Crop water productivity(WP)may act as an indicator of crop responses to water limitation.Organic amendments such as biochar and manure application to soil are suggested for improving soil quality and reducing water requirements from agricultural sector.However,studies exploring the impact of biochar as sole or in combination with organic and/or chemical fertilizers on WP in dry tropical agro-ecosystems are limited.In this study,we observed the effect of rice-husk ash(RHA,biochar)along with farm-yard manure(FYM)and chemical fertilizers(CF)under varying water conditions on soil hydro-physical properties,yield and WP of wheat crop.Water-filled pore space(WFPS),grain and straw yield,irrigation and total water productivity varied significantly(at P<0.001)at treatment level.Grain and straw yield were found higher under sole and combined CF applied treatments.Sole and combined RHA and FYM amendment improved water holding capacity(WHC)and WFPS,whereas a decrease in crop yield was observed as compared to the control.Irrigation and total water productivity were found higher under combined RHA+FYM and sole CF treatments with reduced water supply(except sole CF)as compared to control and sole RHA treatments with full water irrigation.Crop water productivity was found positively correlated with grain and straw yields,however,significant correlations were not observed with WHC and WFPS.Results indicate that increasing soil hydro-physical properties in silty-loam soil may hinder crop yield and WP under sole biochar applied soils.Overall,the implications of the study would help in devising agro-management practices based on combined application of RHA and FYM with reduced chemical fertilizer and water inputs to mitigate the impacts of climate change without compromising crop yield in the highly vulnerable dry tropical agro-ecosystem of India.Moreover,long-term studies are needed in these ecosystems to identify the appropriate agricultural package for mitigating the forthcoming water scarcity conditions.展开更多
Background:Soil microbial biomass,an important nutrient pool for ecosystem nutrient cycling is affected by several factors including climate,edaphic,and land-use change.Himalayan soils are young and unstable and prone...Background:Soil microbial biomass,an important nutrient pool for ecosystem nutrient cycling is affected by several factors including climate,edaphic,and land-use change.Himalayan soils are young and unstable and prone to erosion and degradation due to its topography,bioclimatic conditions and anthropogenic activities such as frequent land-use change.Through this study,we tried to assess how soil parameters and microbial biomass carbon(MBC)of Eastern Himalayan soils originated from gneissic rock change with land-use type,soil depth and season.Chloroform fumigation extraction method was employed to determine MBC from different land-use types.Results:Soil physical and chemical properties varied significantly with season,land-use and soil depth(p<0.001).The maximum values of soil properties were observed in the rainy season followed by summer and winter season in all the study sites.Annual mean microbial biomass carbon was highest in the forest(455.03μg g−1)followed by cardamom agroforestry(392.86μg g−1)and paddy cropland(317.47μg g−1).Microbial biomass carbon exhibited strong significant seasonal difference(p<0.001)in all the land-use types with a peak value in the rainy season(forest-592.78μg g−1;agroforestry-499.84μg g−1 and cropland-365.21μg g−1)and lowest in the winter season(forest−338.46μg g−1;agroforestry-320.28μg g−1 and cropland−265.70μg g−1).The value of microbial biomass carbon decreased significantly with soil depth(p<0.001)but showed an insignificant increase in the second year which corresponds to a change in rainfall pattern.Besides,land-use type,season and soil depth,soil properties also strongly influenced microbial biomass carbon(p<0.001).Microbial quotient was highest in the agroforestry system(2.16%)and least in the subtropical forest(1.91%).Conclusions:Our results indicate that land-use,soil depth and season significantly influenced soil properties and microbial biomass carbon.The physical and chemical properties of soil and MBC exhibit strong seasonality while the type of land-use influenced the microbial activity and biomass of different soil layers in the study sites.Higher soil organic carbon content in cardamom agroforestry and forest in the present study indicates that restoration of the litter layer through retrogressive land-use change accelerates microbial C immobilization which further helps in the maintenance of soil fertility and soil organic carbon sequestration.展开更多
Soil morphological, physical and chemical properties are described at four locations along an elevational transect in the northeastern part of the Moldavian Plateau (Romania). These data contribute to the knowledge of...Soil morphological, physical and chemical properties are described at four locations along an elevational transect in the northeastern part of the Moldavian Plateau (Romania). These data contribute to the knowledge of the soils of this area and to their classification according to the USDA-Soil Taxonomy, FAOWRB and the SRTS-Romanian System. The soils were classified as Inceptisols, Alfisols and Mollisols, according to the USDA-Soil Taxonomy;Gleysol, Chernozem and Luvisol, according to the FAO-WRB and Gleiosol, Cernoziom, Preluvosol, Luvosol, according to the SRTS-Romanian System. The selected soils have a range of properties that represent the soilscape of the Moldavian subcarpathian plateau, characterised by a natural forest with oak as the dominant species. The selected soil parameters decreased with increasing elevation;calcium carbonate and clay leaching and accumulation are the main soil formation processes.展开更多
文摘Some Inceptisols representing the Singla catchment area in Karimgaungedistrict of Assam, India, were studied for lime requirement as influenced by the nature of soilacidity. The electrostatically bonded (EB)-H^+ and EB-Al^(3+) acidities constituted 33 and 67percent of exchangeable acidity while EB-H^+, EB-Al^(3+), exchangeable and pH-dependent aciditiescomprised 6, 14, 20 and 80 percent of total potential acidity. The pH-dependent acidity made a majorcontribution towards the total potential acidity (67%～84%). Grand mean of lime requirementdetermined by the laboratory incubation method and estimated by the methods of New Woodruff,Woodruff and Peech as expressed in MgCaCO_3 ha^(-1) was in the order: Woodruff (15.6) > New Woodruff(14.9) > Peech (5.1) > incubation (5.0). Correlations analysis among different forms of acidity andlime requirement methods with selected soil properties showed that pH in three media, namely water,1 mol L^(-1) KC1 and 0.01 mol L^(-1) CaCl_2, had a significant negative correlation with differentforms of acidity and lime requirement methods. Exchangeable Fe and Al showed significant positivecorrelations with EB-Al^(3+) acidity, exchangeable acidity, pH-dependent acidity and total potentialacidity, and also lime requirement methods. Extractable Al showed positive correlations withdifferent forms of acidity except EB-H^+ and EB-Al^(3+) acidities. The lime requirement by differentmethods depended upon the extractable aluminium. Significant positive correlations existed betweenlime requirements and different forms of acidity of the soils except EB-H^+ acidity and incubationmethod. The nature of soil acidity was mostly pH-dependent. Statistically, the Woodruff method didslightly better than the New Woodruff, incubation and Peech methods at estimating lime requirementand hence the Woodruff procedure may be recommended for routine soil testing because of its speedand simplicity.
文摘Two Inceptisols and an Alfisol of the Indravati Catchment area in Chattisgarh, India, comprising several gradientsin physical and chemical properties were studied to relate phosphate sorption and desorption to soil properties. Fromthe P isotherm curve, the standard P requirement (SPR) of the soils was determined. Phosphate sorption data were alsofitted both to the Langmuir and Freundlich Equations. The mean sorption maximum values for three different soil serieswere: Bastar > Geedam > Mosodi. The fraction of added phosphate sorbed for the 3 series followed this same trend asdid SPR; the phosphate sorption maximum and the maximum phosphate buffering capacity, which were estimated by theLangmuir isotherm; and the Freundlich constant 1/n. However, phosphate desorption, as well as the maximum recoverypercent did not follow this order. The phosphate affinity constant (K) was also different following the same progressionfor the 3 soil series as the Freundlich constant K’, which measured sorption strength. Meanwhile, an inverse order existedfor K and K’ versus the percent desorbed relative to the sorbed as well as the maximum recovery percent. In addition,significant correlation coefficients among sorption parameters of P and soil factors were found.
文摘Phosphorus fractionation and sorption, both separately and jointly, were studied in two cultivated Inceptisols in Northern Greece. Hedley＇s extraction was used to separate soil phosphorus （P） into inorganic Pi （geochemical） and organic Po （biological） fractions. Direct extractable P by Olsen （Olsen-P）, by Mehlich llI （M3-P） and by ammonium oxalate （Pox） was also determined. Phosphorus sorption was carried out with 1：10 soil/solution ratio and sorption parameters were derived from the Langmuir model to the experimental data. Most of the total P occurred in inorganic P forms （74% of Pt）, while organic P comprised only 26% of the Pt. Among the various inorganic P forms relatively large amount of residual P （111 mg kg^-1） was observed, while occluded P in calcium phosphate minerals （d.HCI-Pi） and in Fe, Al-oxides （c.HCI-Pi） existed in equal amounts （83.1 and 83.7 mg kg^-1 respectively）. The phosphorus sorption parameters showed positive relationships with clay content, cation exchange capacity and the sum of exchangeable calcium plus magnesium. Overall, this study indicated that Ca and Mg compounds strongly influence the P chemistry in moderately weathered soils, with relatively high concentration of primary P minerals.
文摘Slash and burn cultivation systems carried out by many farmers in the Amazon region lead to changes in biogeochemical cycles of nutrients. To assess the extent of the impact of shifting cultivation on the soil in a floodplain portion of this region, samples of an Inceptisol surface layer (0 - 5 cm) under primary forest (FP), secondary forest at an advanced stage of recovery (FS), secondary forest at an initial stage of recovery (CAP), agroforestry (SAF), plantations (R?) in indigenous communities and small farmers, and pasture (PAS) in the Upper Solim?es region, Amazonas, were subjected to analysis of chemical composition during the wet (May) and dry (October) seasons, 2007. Soils were fertile with levels of P, K, Ca and Mg above those generally found in Amazon soils. Microbial content did not vary significantly in the systems studied in the wet season, but there was a reduction of around 60% with the change of season, except for soils with SAF. Ammonium nitrogen was predominant in all systems and seasons studied. Nitrate content was higher in R? soil, in two seasons, and lower in PAS. The type of management adopted by farmers in the region’s indigenous agroforestry systems resulted in small changes in P, K, Mg, MBC and mineral-N levels, independent of soil moisture.
基金Agriculture and Natural Resources,University of Tehran for financial support of the study(Grant No.7104017/6/18)。
文摘Quantitative weathering indices are efficient tools in determining the soil development from the underlying rocks.In order to evaluate the effects of climate on the soils developed under an arid to sub-humid climosequence in central Iran,twenty soil-development indices were compared.Twentyfour samples from six pedons were analyzed for routine physico-chemical and geochemical analyses using X-ray fluorescence(XRF).The lowest and highest calculated soil development indices were observed in the arid and sub-humid regions respectively.Among the studied indices,fifteen indices showed similar trends concerning the intensity of weathering.The consistency of such trends reveals the feasibility of using these indices to evaluate basalt weathering rate and soil development in arid,semi-arid and sub-humid regions.This study demonstrated that,among the evaluated weathering indices,the Weathering Index of Parker(WIP)and mass transfer coefficient(τ)were the most proper indices for predicting basalt weathering intensity.This is due to the fact that these indices use the highly mobile earth elements which are the most sensitive elements in basalt chemical weathering.The calculated indices were subdivided into three subgroups including the ratios of mobile/immobile,mobile/mobile and immobile/mobile elements based on the elements used in their calculation.The state of soil evolution was more accurately predicted compared to the other subgroups using the mobile/immobile subgroup of indices.Overall,the weathering indices calculated using the mobile elements are better indicators of weathering intensity,soil formation and the exogenous processes across the arid to sub-humid climosequence.
文摘Agriculture under changing climate scenario is facing major challenges of water scarcity and resource imbalances.Crop water productivity(WP)may act as an indicator of crop responses to water limitation.Organic amendments such as biochar and manure application to soil are suggested for improving soil quality and reducing water requirements from agricultural sector.However,studies exploring the impact of biochar as sole or in combination with organic and/or chemical fertilizers on WP in dry tropical agro-ecosystems are limited.In this study,we observed the effect of rice-husk ash(RHA,biochar)along with farm-yard manure(FYM)and chemical fertilizers(CF)under varying water conditions on soil hydro-physical properties,yield and WP of wheat crop.Water-filled pore space(WFPS),grain and straw yield,irrigation and total water productivity varied significantly(at P<0.001)at treatment level.Grain and straw yield were found higher under sole and combined CF applied treatments.Sole and combined RHA and FYM amendment improved water holding capacity(WHC)and WFPS,whereas a decrease in crop yield was observed as compared to the control.Irrigation and total water productivity were found higher under combined RHA+FYM and sole CF treatments with reduced water supply(except sole CF)as compared to control and sole RHA treatments with full water irrigation.Crop water productivity was found positively correlated with grain and straw yields,however,significant correlations were not observed with WHC and WFPS.Results indicate that increasing soil hydro-physical properties in silty-loam soil may hinder crop yield and WP under sole biochar applied soils.Overall,the implications of the study would help in devising agro-management practices based on combined application of RHA and FYM with reduced chemical fertilizer and water inputs to mitigate the impacts of climate change without compromising crop yield in the highly vulnerable dry tropical agro-ecosystem of India.Moreover,long-term studies are needed in these ecosystems to identify the appropriate agricultural package for mitigating the forthcoming water scarcity conditions.
基金The study is funded by the Department of Science and Technology(DST),Government of India,in the form of a project grant(DST/IS-STAC/CO2-SR-229/14(G)-AICP-AFOLU-IV)to NBL.
文摘Background:Soil microbial biomass,an important nutrient pool for ecosystem nutrient cycling is affected by several factors including climate,edaphic,and land-use change.Himalayan soils are young and unstable and prone to erosion and degradation due to its topography,bioclimatic conditions and anthropogenic activities such as frequent land-use change.Through this study,we tried to assess how soil parameters and microbial biomass carbon(MBC)of Eastern Himalayan soils originated from gneissic rock change with land-use type,soil depth and season.Chloroform fumigation extraction method was employed to determine MBC from different land-use types.Results:Soil physical and chemical properties varied significantly with season,land-use and soil depth(p<0.001).The maximum values of soil properties were observed in the rainy season followed by summer and winter season in all the study sites.Annual mean microbial biomass carbon was highest in the forest(455.03μg g−1)followed by cardamom agroforestry(392.86μg g−1)and paddy cropland(317.47μg g−1).Microbial biomass carbon exhibited strong significant seasonal difference(p<0.001)in all the land-use types with a peak value in the rainy season(forest-592.78μg g−1;agroforestry-499.84μg g−1 and cropland-365.21μg g−1)and lowest in the winter season(forest−338.46μg g−1;agroforestry-320.28μg g−1 and cropland−265.70μg g−1).The value of microbial biomass carbon decreased significantly with soil depth(p<0.001)but showed an insignificant increase in the second year which corresponds to a change in rainfall pattern.Besides,land-use type,season and soil depth,soil properties also strongly influenced microbial biomass carbon(p<0.001).Microbial quotient was highest in the agroforestry system(2.16%)and least in the subtropical forest(1.91%).Conclusions:Our results indicate that land-use,soil depth and season significantly influenced soil properties and microbial biomass carbon.The physical and chemical properties of soil and MBC exhibit strong seasonality while the type of land-use influenced the microbial activity and biomass of different soil layers in the study sites.Higher soil organic carbon content in cardamom agroforestry and forest in the present study indicates that restoration of the litter layer through retrogressive land-use change accelerates microbial C immobilization which further helps in the maintenance of soil fertility and soil organic carbon sequestration.
文摘Soil morphological, physical and chemical properties are described at four locations along an elevational transect in the northeastern part of the Moldavian Plateau (Romania). These data contribute to the knowledge of the soils of this area and to their classification according to the USDA-Soil Taxonomy, FAOWRB and the SRTS-Romanian System. The soils were classified as Inceptisols, Alfisols and Mollisols, according to the USDA-Soil Taxonomy;Gleysol, Chernozem and Luvisol, according to the FAO-WRB and Gleiosol, Cernoziom, Preluvosol, Luvosol, according to the SRTS-Romanian System. The selected soils have a range of properties that represent the soilscape of the Moldavian subcarpathian plateau, characterised by a natural forest with oak as the dominant species. The selected soil parameters decreased with increasing elevation;calcium carbonate and clay leaching and accumulation are the main soil formation processes.
