Structured soils are characterized by the presence of inter- and intra-aggregate pore systems and aggregates, which show varying chemical, physical, and biological properties depending on the aggregate type and land u...Structured soils are characterized by the presence of inter- and intra-aggregate pore systems and aggregates, which show varying chemical, physical, and biological properties depending on the aggregate type and land use system. How far these aspects also affect the ion exchange processes and to what extent the interaction between the carbon distribution and kind of organic substances affect the internal soil strength as well as hydraulic properties like wettability are still under discussion. Thus, the objective of this research was to clarify the effect of soil aggregation on physical and chemical properties of structured soils at two scales: homogenized material and single aggregates. Data obtained by sequentially peeling off soil aggregates layers revealed gradients in the chemical composition from the aggregate surface to the aggregate core. In aggregates from long term untreated forest soils we found lower amounts of carbon in the external layer, while in arable soils the differentiation was not pronounced. However, soil aggregates originating from these sites exhibited a higher concentration of microbial activity in the outer aggregate layer and declined towards the interior. Furthermore, soil depth and the vegetation type affected the wettability. Aggregate strength depended on water suction and differences in tillage treatments.展开更多
Safflower is a Mediterranean-subtropical oil crop, with temperate climate. To assess the suitability of safflower may have certain production potential in organic farming in regions cultivation under temperate climate...Safflower is a Mediterranean-subtropical oil crop, with temperate climate. To assess the suitability of safflower may have certain production potential in organic farming in regions cultivation under temperate climate in low input organic farming, ten cultivars were grown in two years experiment in Lindhoft-Kiel in Northern Germany in clay/sand soil. Pearson correlations reveal that oil yield exhibited tight positive correlations with plant height, plant dry matter, capitula plant-1, achenes capitulum-1 and thousand achene mass (TAM), but was not correlated with days to full flowering or oil concentration. Yield component analysis reveals that achenes capitulum1 had the major influence on the variation of oil yield of all studied cultivars, followed by capitula plant1 and TAM, while the oil concentration had slightly negative influence, and the plant density was negatively associated with oil yield. Although two years field experiment is not enough to analyse the performance of safflower adaptability to certain region, it can be concluded that the most adaptive cultivars are PI-209286 originated from Romania, and cultivar CART-19/89 originated from Poland, while the less adaptive cultivars were DO-13/03 and DO-15/03 with German origin in addition to the Canadian cultivar PI-572475/Saffire. The most striking yield component that contributes to the high yield is achene capitulumt, which can be used as a base for selecting cultivars adaptive to humid cold conditions. The growth period between full flowering and harvest influencing this yield component must be given attention to avoid low temperature and rainfall by tuning sowing date to improve yield at these conditions.展开更多
Safflower represents an important oil crop internationally and may have a production potential under low input conditions, but its putatively high phosphorous use efficiency is not sustained. This study aims to direct...Safflower represents an important oil crop internationally and may have a production potential under low input conditions, but its putatively high phosphorous use efficiency is not sustained. This study aims to directly compare safflower with sunflower in terms of phosphorus use efficiency in nutrient solution under controlled conditions. Growth of both species responded strongly to increasing P supply. Safflower recovers less proportion of added P than sunflower. External P requirement ((g P supply (100 g dry matter (DM) produced)~) was higher in safflower than sunflower. The efficiency of the crops for DM production based on accumulated P (mg P potl, efficiency ratio), and P concentration in DM ((mg P (g DM)'I), utilization index) were interpreted using Michaelis-Menten kinetics as growth response curves. Accordingly, Km constant was lower in sunflower compared to safflower in terms of utilization index, but both were similar in terms of efficiency ratio. High Km constant in safflower in terms of utilization index indicates the high P concentration in tissues to produce 50% of potential maximum DM, consequently less efficient crop. Utilization efficiency contributed more than uptake efficiency in overall PUE in the efficient cultivar and could be the cause of its superiority in PUE. It can be concluded that safflower has a high requirement for P with respect to growth, sunflower is more efficient in terms of uptake and utilization of P at optimal and sub-optimal P supplies indicating that safflower can not be considered a low nutrient input crop compared to sunflower with respect to phosphorus.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
Soil rheology characterises the flow behaviour of soils at the particle-particle to aggregate scale.Amplitude sweep tests(ASTs)are often the method of choice for parameterizing soil flow properties,such as the shear s...Soil rheology characterises the flow behaviour of soils at the particle-particle to aggregate scale.Amplitude sweep tests(ASTs)are often the method of choice for parameterizing soil flow properties,such as the shear strain values at the end of the linear viscoelastic range(i.e.,the deformation is mainly elastic)and at the yield point(i.e.,elastic equals plastic deformation).Samples from seven soil profiles and five soil depths of Chernozems,collected in the Maidanetske study area,close to Uman City of Ukraine,were analysed to evaluate the effect of soil organic carbon(SOC)on the parameters related to soil microstructural stability derived from ASTs.Soil organic carbon was removed with H_(2)O_(2)to determine the soil texture-dependent values of soil rheological properties,which were compared to the values determined for samples with intact water-stable aggregates.The shear resistance-related parameters increased for aggregated soil samples compared to SOC-free soil samples,indicating an increase in soil stability due to SOC.In contrast,the values of the overall viscoelasticity and the shear strain were reduced for aggregated soil samples,indicating decreased soil stability.Pedotransfer functions were applied to predict the shear strain-dependent loss and storage moduli and shear stress values as a function of SOC depletion.Coarse particles(630–2000μm)and volumetric water content improved the models.We conclude that increased SOC content,through the gluing and cementing effects of SOC and altered aggregate shapes compared to SOC-free soil materials,contributes to higher microstructural strength.However,the increased water content in the SOC-containing soil samples reversed soil strengthening effect.This was due to the fact that a more rapid increase in positive water pressure under shear stress weakened the samples and the spherical aggregates began to rotate more easily,thus loosing energy,when compared to platy particles of the SOC-free soil materials.展开更多
The individual and combined effects of biochar(B)and inorganic fertiliser(F)have all been widely proofed to improve soil fertility and enhance crop growth and yield under irrigation(I)and rain fed conditions.However,t...The individual and combined effects of biochar(B)and inorganic fertiliser(F)have all been widely proofed to improve soil fertility and enhance crop growth and yield under irrigation(I)and rain fed conditions.However,the strength of their individual and combined effects on crop productivity has been scarcely reported.In addition,few studies have assessed their individual and co-application effects on economic returns.Therefore,a 2-year field experiment which consisted of factorial combination of irrigation(I)[100%full irrigation(FI),80%FI and 60%FI],biochar(0 and 20 t/ha)and fertiliser(0 and 300 kg/ha)was conducted.According to the results,irrigation was the dominant factor that influences maize grain yield,followed by inorganic fertiliser and biochar,and they were all significant in their main effects.The strength of interaction effects among,I,F and B on maize grain yield follow the sequence F×I>B×F>B×I.The economic analysis showed that the ternary combination of B,F and I was more economical than the binary combination of B plus I,and F plus I(in that order),when compared with the standalone application of I at maximum production in the field experiment.In addition,combined applications of biochar and fertiliser improved soil nutrients,nutrient uptake in all irrigation treatments,compared to the standalone applications of biochar or fertiliser.Further research is,therefore,recommended for long-term evaluation of the economic viability of integrating biochar with fertiliser under irrigation.展开更多
基金Project supported by the fund of the DFG (Deutsche Forschung Gemeinschaft) as part of the DFG priority program 1090: 'Soils as source and sink for CO2-mechanisms and regulation of organic matter stabilization in soils' (No. DFG SPP 1090).
文摘Structured soils are characterized by the presence of inter- and intra-aggregate pore systems and aggregates, which show varying chemical, physical, and biological properties depending on the aggregate type and land use system. How far these aspects also affect the ion exchange processes and to what extent the interaction between the carbon distribution and kind of organic substances affect the internal soil strength as well as hydraulic properties like wettability are still under discussion. Thus, the objective of this research was to clarify the effect of soil aggregation on physical and chemical properties of structured soils at two scales: homogenized material and single aggregates. Data obtained by sequentially peeling off soil aggregates layers revealed gradients in the chemical composition from the aggregate surface to the aggregate core. In aggregates from long term untreated forest soils we found lower amounts of carbon in the external layer, while in arable soils the differentiation was not pronounced. However, soil aggregates originating from these sites exhibited a higher concentration of microbial activity in the outer aggregate layer and declined towards the interior. Furthermore, soil depth and the vegetation type affected the wettability. Aggregate strength depended on water suction and differences in tillage treatments.
文摘Safflower is a Mediterranean-subtropical oil crop, with temperate climate. To assess the suitability of safflower may have certain production potential in organic farming in regions cultivation under temperate climate in low input organic farming, ten cultivars were grown in two years experiment in Lindhoft-Kiel in Northern Germany in clay/sand soil. Pearson correlations reveal that oil yield exhibited tight positive correlations with plant height, plant dry matter, capitula plant-1, achenes capitulum-1 and thousand achene mass (TAM), but was not correlated with days to full flowering or oil concentration. Yield component analysis reveals that achenes capitulum1 had the major influence on the variation of oil yield of all studied cultivars, followed by capitula plant1 and TAM, while the oil concentration had slightly negative influence, and the plant density was negatively associated with oil yield. Although two years field experiment is not enough to analyse the performance of safflower adaptability to certain region, it can be concluded that the most adaptive cultivars are PI-209286 originated from Romania, and cultivar CART-19/89 originated from Poland, while the less adaptive cultivars were DO-13/03 and DO-15/03 with German origin in addition to the Canadian cultivar PI-572475/Saffire. The most striking yield component that contributes to the high yield is achene capitulumt, which can be used as a base for selecting cultivars adaptive to humid cold conditions. The growth period between full flowering and harvest influencing this yield component must be given attention to avoid low temperature and rainfall by tuning sowing date to improve yield at these conditions.
文摘Safflower represents an important oil crop internationally and may have a production potential under low input conditions, but its putatively high phosphorous use efficiency is not sustained. This study aims to directly compare safflower with sunflower in terms of phosphorus use efficiency in nutrient solution under controlled conditions. Growth of both species responded strongly to increasing P supply. Safflower recovers less proportion of added P than sunflower. External P requirement ((g P supply (100 g dry matter (DM) produced)~) was higher in safflower than sunflower. The efficiency of the crops for DM production based on accumulated P (mg P potl, efficiency ratio), and P concentration in DM ((mg P (g DM)'I), utilization index) were interpreted using Michaelis-Menten kinetics as growth response curves. Accordingly, Km constant was lower in sunflower compared to safflower in terms of utilization index, but both were similar in terms of efficiency ratio. High Km constant in safflower in terms of utilization index indicates the high P concentration in tissues to produce 50% of potential maximum DM, consequently less efficient crop. Utilization efficiency contributed more than uptake efficiency in overall PUE in the efficient cultivar and could be the cause of its superiority in PUE. It can be concluded that safflower has a high requirement for P with respect to growth, sunflower is more efficient in terms of uptake and utilization of P at optimal and sub-optimal P supplies indicating that safflower can not be considered a low nutrient input crop compared to sunflower with respect to phosphorus.
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.
文摘Soil rheology characterises the flow behaviour of soils at the particle-particle to aggregate scale.Amplitude sweep tests(ASTs)are often the method of choice for parameterizing soil flow properties,such as the shear strain values at the end of the linear viscoelastic range(i.e.,the deformation is mainly elastic)and at the yield point(i.e.,elastic equals plastic deformation).Samples from seven soil profiles and five soil depths of Chernozems,collected in the Maidanetske study area,close to Uman City of Ukraine,were analysed to evaluate the effect of soil organic carbon(SOC)on the parameters related to soil microstructural stability derived from ASTs.Soil organic carbon was removed with H_(2)O_(2)to determine the soil texture-dependent values of soil rheological properties,which were compared to the values determined for samples with intact water-stable aggregates.The shear resistance-related parameters increased for aggregated soil samples compared to SOC-free soil samples,indicating an increase in soil stability due to SOC.In contrast,the values of the overall viscoelasticity and the shear strain were reduced for aggregated soil samples,indicating decreased soil stability.Pedotransfer functions were applied to predict the shear strain-dependent loss and storage moduli and shear stress values as a function of SOC depletion.Coarse particles(630–2000μm)and volumetric water content improved the models.We conclude that increased SOC content,through the gluing and cementing effects of SOC and altered aggregate shapes compared to SOC-free soil materials,contributes to higher microstructural strength.However,the increased water content in the SOC-containing soil samples reversed soil strengthening effect.This was due to the fact that a more rapid increase in positive water pressure under shear stress weakened the samples and the spherical aggregates began to rotate more easily,thus loosing energy,when compared to platy particles of the SOC-free soil materials.
基金We appreciate the research grant from the Tertiary Education Trust Fund(TETFUND)Nigeria,which was used to fund part of this research.
文摘The individual and combined effects of biochar(B)and inorganic fertiliser(F)have all been widely proofed to improve soil fertility and enhance crop growth and yield under irrigation(I)and rain fed conditions.However,the strength of their individual and combined effects on crop productivity has been scarcely reported.In addition,few studies have assessed their individual and co-application effects on economic returns.Therefore,a 2-year field experiment which consisted of factorial combination of irrigation(I)[100%full irrigation(FI),80%FI and 60%FI],biochar(0 and 20 t/ha)and fertiliser(0 and 300 kg/ha)was conducted.According to the results,irrigation was the dominant factor that influences maize grain yield,followed by inorganic fertiliser and biochar,and they were all significant in their main effects.The strength of interaction effects among,I,F and B on maize grain yield follow the sequence F×I>B×F>B×I.The economic analysis showed that the ternary combination of B,F and I was more economical than the binary combination of B plus I,and F plus I(in that order),when compared with the standalone application of I at maximum production in the field experiment.In addition,combined applications of biochar and fertiliser improved soil nutrients,nutrient uptake in all irrigation treatments,compared to the standalone applications of biochar or fertiliser.Further research is,therefore,recommended for long-term evaluation of the economic viability of integrating biochar with fertiliser under irrigation.