The common microscale to nanoscale pore types were introduced and divided into organic and inorganic pores to estimate their contributions to porosity in the Lower Silurian Longmaxi Formation shale of southeast Chongq...The common microscale to nanoscale pore types were introduced and divided into organic and inorganic pores to estimate their contributions to porosity in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Following the material balance principle, the organic porosity values, which changed with formation subsidence and thermal evolution, were calculated using chemical kinetics methods and corrected via the organic porosity correction coefficient, which was obtained from field emission scanning electron microscopy. Grain density values were determined using the contents and true densities of compositions in the shale samples. The total porosity was calculated based on the grain and bulk densities. The inorganic porosity was determined from the difference between the total porosity and organic porosity at the same depth. The results show that inorganic pores mainly contain microfractures, microchannels, clay intergranular pores, intercrystalline pores and intracrystalline pores in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Organic pores mainly include organopore and fossil pore. The total porosity, organic porosity and inorganic porosity of organic-rich shale samples can be quantitatively evaluated using this method. The total porosity, organic porosity and inorganic porosity values of the Longmaxi Formation shale samples from the well Pyl in southeast Chongqing lie in 2.75%-6.14%, 0.08%-2.52% and 1.41%-4.92% with average values of 4.34%, 0.95% and 3.39%, respectively. The contributions of the inorganic pores to the total porosity are significantly greater than those of the organic pores.展开更多
Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhous...Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhouse experiment was conducted to investigate effects of wheat straw biochar （0-160 mL L-1） and super absorbent polymer （SAP, 0.8 g L-1） on physical and chemical properties of a substrate based on spent pig litter compost and the growth of water spinach （Ipomoea aquatica Forsk）. Total porosity, water-holding capacity~ pH and electrical conductivity （EC） of the substrate significantly increased with increasing biochar rates, especially in the substrate without SAP. The values of pH and EC were significantly lower in the substrate with SAP than those without SAP at the high biochar application rates （100-160 mL L-l）. The germination rates of water spinach decreased with increasing biochar rates when biochar was added alone （76.9%-83.7%）, whereas the rates increased to 83.6%-85.8% when biochar was added in combination with SAP. Growth parameters of water spinach and nutrient uptake by shoots and roots increased with increasing biochar rates and reached the maximum values at the biochar rate of 100 mL L-1. There were significant cubic relationships between the uptake of nutrients （N, P, and K） and biochar rates, both with and without SAP addition. In order to avoid negative effects on plant growth, the biochar application rate should be controlled at an optimal level （100 mL L-1 ）. The SAP addition not only enhanced the positive effects of biochar application on the properties of the substrate, but also inhibited the excessive rise of pH and EC following biochar additions, which led to better plant growth and enhanced nutrient uptakes by water spinach.展开更多
Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of...Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of improved physical quality of the amended soil.However, the mechanisms for this improvement are still poorly understood. This study investigated the effect of woodchip biochar amendment on micro-structural development, micro-and macro-structural stability, and resilience of two differently textured soils,fine sand(FS) and sandy loam(SL). Test substrates were prepared by adding 50 or 100 g kg^(-1) biochar to FS or SL. Total porosity and plant available water were significantly increased in both soils. Moreover, compressive strength of the aggregates was significantly decreased when biochar amount was doubled. Mechanical resilience of the aggregates at both micro-and macro-scale was improved in the biochar-amended soils, impacting the cohesion and compressive behavior. A combination of these effects will result in an improved pore structure and aeration. Consequently, the physicochemical environment for plants and microbes is improved. Furthermore, the improved stability properties will result in better capacity of the biochar-amended soil to recover from the myriad of mechanical stresses imposed under arable systems, including vehicle traffic, to the weight of overburden soil. However, it was noted that doubling the amendment rate did not in any case offer any remarkable additional improvement in these properties, suggesting a further need to investigate the optimal amendment rate.展开更多
Wood extraction by heavy machinery has always been associated with soil disturbance in mountain forests,and the degree of soil degradation is influenced by several factors,including site and soil characteristics,soil ...Wood extraction by heavy machinery has always been associated with soil disturbance in mountain forests,and the degree of soil degradation is influenced by several factors,including site and soil characteristics,soil moisture,type of equipment used,and number of machine passes.The effects of ground-based skidding operations on the physical properties of soils with different texture were evaluated at different levels of traffic frequency and trail gradient at two sites in an Iranian temperate forest.The treatments included combinations of three different traffic frequencies(3,8,and 14 passes of a rubber-tired cable skidder),three levels of trail gradient(<10%,10%–20%,and>20%) and two soil texture classes,clay loam(Site 1) and sandy loam(Site 2).The average gravimetric soil moisture at the time of skidding was 23%(Site 1) and 20%(Site 2).The average dry bulk density and total porosity of the undisturbed soil(control) were0.71 g cm-3 and 73.3% at Site 1(clay loam) and 0.86 g cm-3and 59.1% at Site 2(sandy loam),respectively.At site 1(fine-textured soil),rutting began after three passes of the skidder,whereas at site 2(coarse-textured soil),rutting occurred only after eight passes.Independent of the traffic frequency and trail gradient,machine impact on the fine-textured soil caused greater increases in bulk density and rut depth compared to that on the coarse-textured soil.After three skidder passes and independent from trail gradients,dry bulk density at Site 1 increased by 54.8% compared to that of the undisturbed control,and the increase was 45.5% at Site 2.Therefore,medium to fine-textured soils are more susceptible to compaction than coarse-textured soils.Such soils,especially when moist,should be protected using brush mats created from harvesting residues during the forest processing phase.展开更多
基金Financial supports from the National Science Foundation of China(grants No.41530315,41302101 and 41330313)the National Science and Technology Major Project of China(grant No.2016ZX05061)+1 种基金the Natural Science Foundation of Shandong Province(grant No.ZR2016DL07)the Fundamental Research Funds for the Central Universities(grant No.18CX02071A)
文摘The common microscale to nanoscale pore types were introduced and divided into organic and inorganic pores to estimate their contributions to porosity in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Following the material balance principle, the organic porosity values, which changed with formation subsidence and thermal evolution, were calculated using chemical kinetics methods and corrected via the organic porosity correction coefficient, which was obtained from field emission scanning electron microscopy. Grain density values were determined using the contents and true densities of compositions in the shale samples. The total porosity was calculated based on the grain and bulk densities. The inorganic porosity was determined from the difference between the total porosity and organic porosity at the same depth. The results show that inorganic pores mainly contain microfractures, microchannels, clay intergranular pores, intercrystalline pores and intracrystalline pores in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Organic pores mainly include organopore and fossil pore. The total porosity, organic porosity and inorganic porosity of organic-rich shale samples can be quantitatively evaluated using this method. The total porosity, organic porosity and inorganic porosity values of the Longmaxi Formation shale samples from the well Pyl in southeast Chongqing lie in 2.75%-6.14%, 0.08%-2.52% and 1.41%-4.92% with average values of 4.34%, 0.95% and 3.39%, respectively. The contributions of the inorganic pores to the total porosity are significantly greater than those of the organic pores.
基金supported by the National Natural Science Foundation of China (No.41401259)the General Financial Grant from the China Postdoctoral Science Foundation (No.2014M551528)+1 种基金the Independent Innovation Project of Jiangsu Province,China (No.CX(14)2035)the Special Scientific Research Fund of Agricultural Public Welfare Profession of China (No.201203050)
文摘Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhouse experiment was conducted to investigate effects of wheat straw biochar （0-160 mL L-1） and super absorbent polymer （SAP, 0.8 g L-1） on physical and chemical properties of a substrate based on spent pig litter compost and the growth of water spinach （Ipomoea aquatica Forsk）. Total porosity, water-holding capacity~ pH and electrical conductivity （EC） of the substrate significantly increased with increasing biochar rates, especially in the substrate without SAP. The values of pH and EC were significantly lower in the substrate with SAP than those without SAP at the high biochar application rates （100-160 mL L-l）. The germination rates of water spinach decreased with increasing biochar rates when biochar was added alone （76.9%-83.7%）, whereas the rates increased to 83.6%-85.8% when biochar was added in combination with SAP. Growth parameters of water spinach and nutrient uptake by shoots and roots increased with increasing biochar rates and reached the maximum values at the biochar rate of 100 mL L-1. There were significant cubic relationships between the uptake of nutrients （N, P, and K） and biochar rates, both with and without SAP addition. In order to avoid negative effects on plant growth, the biochar application rate should be controlled at an optimal level （100 mL L-1 ）. The SAP addition not only enhanced the positive effects of biochar application on the properties of the substrate, but also inhibited the excessive rise of pH and EC following biochar additions, which led to better plant growth and enhanced nutrient uptakes by water spinach.
基金the George Foster Research Fellowship provided by Alexander yon Humboldt Fellowship of Germany.
文摘Biochars are, amongst other available amendment materials, considered as an attractive tool in agriculture for carbon sequestration and improvement of soil functions. The latter is widely discussed as a consequence of improved physical quality of the amended soil.However, the mechanisms for this improvement are still poorly understood. This study investigated the effect of woodchip biochar amendment on micro-structural development, micro-and macro-structural stability, and resilience of two differently textured soils,fine sand(FS) and sandy loam(SL). Test substrates were prepared by adding 50 or 100 g kg^(-1) biochar to FS or SL. Total porosity and plant available water were significantly increased in both soils. Moreover, compressive strength of the aggregates was significantly decreased when biochar amount was doubled. Mechanical resilience of the aggregates at both micro-and macro-scale was improved in the biochar-amended soils, impacting the cohesion and compressive behavior. A combination of these effects will result in an improved pore structure and aeration. Consequently, the physicochemical environment for plants and microbes is improved. Furthermore, the improved stability properties will result in better capacity of the biochar-amended soil to recover from the myriad of mechanical stresses imposed under arable systems, including vehicle traffic, to the weight of overburden soil. However, it was noted that doubling the amendment rate did not in any case offer any remarkable additional improvement in these properties, suggesting a further need to investigate the optimal amendment rate.
基金financially supported by University of Guilan, Iran
文摘Wood extraction by heavy machinery has always been associated with soil disturbance in mountain forests,and the degree of soil degradation is influenced by several factors,including site and soil characteristics,soil moisture,type of equipment used,and number of machine passes.The effects of ground-based skidding operations on the physical properties of soils with different texture were evaluated at different levels of traffic frequency and trail gradient at two sites in an Iranian temperate forest.The treatments included combinations of three different traffic frequencies(3,8,and 14 passes of a rubber-tired cable skidder),three levels of trail gradient(<10%,10%–20%,and>20%) and two soil texture classes,clay loam(Site 1) and sandy loam(Site 2).The average gravimetric soil moisture at the time of skidding was 23%(Site 1) and 20%(Site 2).The average dry bulk density and total porosity of the undisturbed soil(control) were0.71 g cm-3 and 73.3% at Site 1(clay loam) and 0.86 g cm-3and 59.1% at Site 2(sandy loam),respectively.At site 1(fine-textured soil),rutting began after three passes of the skidder,whereas at site 2(coarse-textured soil),rutting occurred only after eight passes.Independent of the traffic frequency and trail gradient,machine impact on the fine-textured soil caused greater increases in bulk density and rut depth compared to that on the coarse-textured soil.After three skidder passes and independent from trail gradients,dry bulk density at Site 1 increased by 54.8% compared to that of the undisturbed control,and the increase was 45.5% at Site 2.Therefore,medium to fine-textured soils are more susceptible to compaction than coarse-textured soils.Such soils,especially when moist,should be protected using brush mats created from harvesting residues during the forest processing phase.
