During production process,the below mentioned errors appeared in the original article and inadvertently published with error.The corrections are as given below.
The undrained shear strength （su） of fine-grained soils that can be measured in situ and in laboratory isone of the key geotechnical parameters. The unconfined compression test （UCT） is widely used in laboratoryto...The undrained shear strength （su） of fine-grained soils that can be measured in situ and in laboratory isone of the key geotechnical parameters. The unconfined compression test （UCT） is widely used in laboratoryto measure this parameter due to its simplicity; however, it is severely affected by sampledisturbance. The vane shear test （VST） technique that is less sensitive to sample disturbance involves acorrection factor against the soil plasticity, commonly known as the Bjerrum＇s correction factor, m. Thisstudy aims to reevaluate the Bjerrum＇s correction factor in consideration of a different approach and arelatively new method of testing. Atterberg limits test, miniature VST, and reverse extrusion test （RET）were conducted on 120 remolded samples. The effect of soil plasticity on undrained shear strength wasexamined using the liquidity index instead of Bjerrum＇s correction factor. In comparison with the resultobatined using the Bjerrum＇s correction factor, the undrained shear strength was better representedwhen su values were correlated with the liquidity index. The results were validated by the RET, whichwas proven to take into account soil plasticity with a reliable degree of accuracy. This study also showsthat the RET has strong promise as a new tool for testing undrained shear strength of fine-grained soils.展开更多
When the electronic temperature sensor was incorporated into a system of soil water tension and the insidetube temperature was monitored in real time, it is concluded that the inside temperature increased by 26.9 ℃ a...When the electronic temperature sensor was incorporated into a system of soil water tension and the insidetube temperature was monitored in real time, it is concluded that the inside temperature increased by 26.9 ℃ and the inside pressure changed about 14.6 Kpa, when the pottery soil was replaced by the sealing plug. When the soil water was relatively stable in the experimental salvers, the in-side pressure stil varied regularly with the temperature. When the inside temperature increased by 22.2 ℃, the inside pressure varied about 7.4 Kpa. Through com-pensation calculation of the inside tension, the temperature in the warming and cooling periods was compensated, which was useful to correct the tension measurement errors induced from the changing temperature. When the measuring interval was 4 hours and the temperature difference was 18.1 ℃, the tension difference of both points was only 0.278 Kpa, compared to the difference up to 6.5 Kpa before compensation.展开更多
In this study, sea surface salinity(SSS) Level 3(L3) daily product derived from soil moisture active passive(SMAP)during the year 2016, was validated and compared with SSS daily products derived from soil Moisture and...In this study, sea surface salinity(SSS) Level 3(L3) daily product derived from soil moisture active passive(SMAP)during the year 2016, was validated and compared with SSS daily products derived from soil Moisture and ocean salinity(SMOS) and in-situ measurements. Generally, the root mean square error(RMSE) of the daily SSS products is larger along the coastal areas and at high latitudes and is smaller in the tropical regions and open oceans. Comparisons between the two types of daily satellite SSS product revealed that the RMSE was higher in the daily SMOS product than in the SMAP, whereas the bias of the daily SMOS was observed to be less than that of the SMAP when compared with Argo floats data. In addition, the latitude-dependent bias and RMSE of the SMAP SSS were found to be primarily influenced by the precipitation and the sea surface temperature(SST). Then, a regression analysis method which has adopted the precipitation and SST data was used to correct the larger bias of the daily SMAP product. It was confirmed that the corrected daily SMAP product could be used for assimilation in high-resolution forecast models, due to the fact that it was demonstrated to be unbiased and much closer to the in-situ measurements than the original uncorrected SMAP product.展开更多
Among Brazilian soils orders, there are some of it classified as acid soils, which need correction to guarantee crop productivity. Currently, limestone is the most used soil corrective and wood ash has been a sustaina...Among Brazilian soils orders, there are some of it classified as acid soils, which need correction to guarantee crop productivity. Currently, limestone is the most used soil corrective and wood ash has been a sustainable alternative to this process. Thus, the objective was to evaluate the effect of two correctives of soil acidity on an Oxisol collected in the Brazilian Cerrado area using limestone and wood ash and the effect of soil correction on initial growth of cowpea. Two greenhouse experiments were carried out: 1) with limestone, using base saturation levels (V%) of 0, 20, 40, 60 and 80;and 2) wood ash, with doses of 0, 8, 16, 24 and 32 g⋅dm−3, both in five randomized blocks. At 40 days after sowing, it was verified that pH values were within the range considered ideal for soil (pH of 5 to 7), according to the increase of base saturation levels and wood ash doses, but limestone provided faster results. Initial growth of cowpea was positively influenced by soil correction with use of both correctives. Wood ash and limestone increased soil pH to adequate values and resulted in better initial crop development.展开更多
Dynamic monitoring of plant cover and soil erosion often uses remote sensing data, especially for estimating the plant cover rate (vegetation coverage) by vegetation index. However, the latter is influenced by atmosph...Dynamic monitoring of plant cover and soil erosion often uses remote sensing data, especially for estimating the plant cover rate (vegetation coverage) by vegetation index. However, the latter is influenced by atmospheric effects and methods for correcting them are still imperfect and disputed. This research supposed and practiced an indirect, fast, and operational method to conduct atmospheric correction of images for getting comparable vegetation index values in different times. It tries to find a variable free from atmospheric effects, e.g., the mean vegetation coverage value of the whole study area, as a basis to reduce atmospheric correction parameters by establishing mathematical models and conducting simulation calculations. Using these parameters, the images can be atmospherically corrected. And then, the vegetation index and corresponding vegetation coverage values for all pixels, the vegetation coverage maps and coverage grade maps for different years were calculated, i.e., the plant cover monitoring was realized. Using the vegetation coverage grade maps and the ground slope grade map from a DEM to generate soil erosion grade maps for different years, the soil erosion monitoring was also realized. The results show that in the study area the vegetation coverage was the lowest in 1976, much better in 1989, but a bit worse again in 2001. Towards the soil erosion, it had been mitigated continuously from 1976 to 1989 and then to 2001. It is interesting that a little decrease of vegetation coverage from 1989 to 2001 did not lead to increase of soil erosion. The reason is that the decrease of vegetation coverage was chiefly caused by urbanization and thus mainly occurred in very gentle terrains, where soil erosion was naturally slight. The results clearly indicate the details of plant cover and soil erosion change in 25 years and also offer a scientific foundation for plant and soil conservation.展开更多
Large amounts of phytosiderophore are detected from both the solution and the rhizosphere soil when cereal crops are under Fe deficiency stress. The extension of phytosiderophore in the rhizosphere soil is found only ...Large amounts of phytosiderophore are detected from both the solution and the rhizosphere soil when cereal crops are under Fe deficiency stress. The extension of phytosiderophore in the rhizosphere soil is found only within 1 mm apart from the root surface. The rate of phytosiderophore secretion is negatively related to chlorophyll content in young leaves and positively related to the Fe-solubilizing capacity. Results from in vitro experiments show 10 μmoles mugineic acid can dissolve 501 μg Fe from iron hydroxide and 146 ug from strengite. Thus, phytosiderophore can considerably enhance the soil iron availability by increasing the solubility of amorphous iron hydroxide and iron phosphate, and active Fe is consequently accumulated in the plant rhizosphere , 43% higher than in the bulk soils. There is evidence to support that mugineic acid chelates with Fe3+at a rate of 1:1 in the acid condition. In addition ,we observe mugineic acid has certain effects on mobilization of P as well as Fe by dissolving the insoluble iron phosphate. And phytosiderophore seems to be an effective remedy for the chlorosis of dicotyledonous plants.展开更多
文摘During production process,the below mentioned errors appeared in the original article and inadvertently published with error.The corrections are as given below.
文摘The undrained shear strength （su） of fine-grained soils that can be measured in situ and in laboratory isone of the key geotechnical parameters. The unconfined compression test （UCT） is widely used in laboratoryto measure this parameter due to its simplicity; however, it is severely affected by sampledisturbance. The vane shear test （VST） technique that is less sensitive to sample disturbance involves acorrection factor against the soil plasticity, commonly known as the Bjerrum＇s correction factor, m. Thisstudy aims to reevaluate the Bjerrum＇s correction factor in consideration of a different approach and arelatively new method of testing. Atterberg limits test, miniature VST, and reverse extrusion test （RET）were conducted on 120 remolded samples. The effect of soil plasticity on undrained shear strength wasexamined using the liquidity index instead of Bjerrum＇s correction factor. In comparison with the resultobatined using the Bjerrum＇s correction factor, the undrained shear strength was better representedwhen su values were correlated with the liquidity index. The results were validated by the RET, whichwas proven to take into account soil plasticity with a reliable degree of accuracy. This study also showsthat the RET has strong promise as a new tool for testing undrained shear strength of fine-grained soils.
基金Supported by Jiangsu Agricultural Self-innovation Fund[CX(13)3031]~~
文摘When the electronic temperature sensor was incorporated into a system of soil water tension and the insidetube temperature was monitored in real time, it is concluded that the inside temperature increased by 26.9 ℃ and the inside pressure changed about 14.6 Kpa, when the pottery soil was replaced by the sealing plug. When the soil water was relatively stable in the experimental salvers, the in-side pressure stil varied regularly with the temperature. When the inside temperature increased by 22.2 ℃, the inside pressure varied about 7.4 Kpa. Through com-pensation calculation of the inside tension, the temperature in the warming and cooling periods was compensated, which was useful to correct the tension measurement errors induced from the changing temperature. When the measuring interval was 4 hours and the temperature difference was 18.1 ℃, the tension difference of both points was only 0.278 Kpa, compared to the difference up to 6.5 Kpa before compensation.
基金The National Key Research and Development Program of China under contract Nos 2016YFC1401409 and 2016YFC1401704the National Natural Science Foundation of China under contract Nos 41506031 and 41606029.
文摘In this study, sea surface salinity(SSS) Level 3(L3) daily product derived from soil moisture active passive(SMAP)during the year 2016, was validated and compared with SSS daily products derived from soil Moisture and ocean salinity(SMOS) and in-situ measurements. Generally, the root mean square error(RMSE) of the daily SSS products is larger along the coastal areas and at high latitudes and is smaller in the tropical regions and open oceans. Comparisons between the two types of daily satellite SSS product revealed that the RMSE was higher in the daily SMOS product than in the SMAP, whereas the bias of the daily SMOS was observed to be less than that of the SMAP when compared with Argo floats data. In addition, the latitude-dependent bias and RMSE of the SMAP SSS were found to be primarily influenced by the precipitation and the sea surface temperature(SST). Then, a regression analysis method which has adopted the precipitation and SST data was used to correct the larger bias of the daily SMAP product. It was confirmed that the corrected daily SMAP product could be used for assimilation in high-resolution forecast models, due to the fact that it was demonstrated to be unbiased and much closer to the in-situ measurements than the original uncorrected SMAP product.
文摘Among Brazilian soils orders, there are some of it classified as acid soils, which need correction to guarantee crop productivity. Currently, limestone is the most used soil corrective and wood ash has been a sustainable alternative to this process. Thus, the objective was to evaluate the effect of two correctives of soil acidity on an Oxisol collected in the Brazilian Cerrado area using limestone and wood ash and the effect of soil correction on initial growth of cowpea. Two greenhouse experiments were carried out: 1) with limestone, using base saturation levels (V%) of 0, 20, 40, 60 and 80;and 2) wood ash, with doses of 0, 8, 16, 24 and 32 g⋅dm−3, both in five randomized blocks. At 40 days after sowing, it was verified that pH values were within the range considered ideal for soil (pH of 5 to 7), according to the increase of base saturation levels and wood ash doses, but limestone provided faster results. Initial growth of cowpea was positively influenced by soil correction with use of both correctives. Wood ash and limestone increased soil pH to adequate values and resulted in better initial crop development.
文摘Dynamic monitoring of plant cover and soil erosion often uses remote sensing data, especially for estimating the plant cover rate (vegetation coverage) by vegetation index. However, the latter is influenced by atmospheric effects and methods for correcting them are still imperfect and disputed. This research supposed and practiced an indirect, fast, and operational method to conduct atmospheric correction of images for getting comparable vegetation index values in different times. It tries to find a variable free from atmospheric effects, e.g., the mean vegetation coverage value of the whole study area, as a basis to reduce atmospheric correction parameters by establishing mathematical models and conducting simulation calculations. Using these parameters, the images can be atmospherically corrected. And then, the vegetation index and corresponding vegetation coverage values for all pixels, the vegetation coverage maps and coverage grade maps for different years were calculated, i.e., the plant cover monitoring was realized. Using the vegetation coverage grade maps and the ground slope grade map from a DEM to generate soil erosion grade maps for different years, the soil erosion monitoring was also realized. The results show that in the study area the vegetation coverage was the lowest in 1976, much better in 1989, but a bit worse again in 2001. Towards the soil erosion, it had been mitigated continuously from 1976 to 1989 and then to 2001. It is interesting that a little decrease of vegetation coverage from 1989 to 2001 did not lead to increase of soil erosion. The reason is that the decrease of vegetation coverage was chiefly caused by urbanization and thus mainly occurred in very gentle terrains, where soil erosion was naturally slight. The results clearly indicate the details of plant cover and soil erosion change in 25 years and also offer a scientific foundation for plant and soil conservation.
文摘Large amounts of phytosiderophore are detected from both the solution and the rhizosphere soil when cereal crops are under Fe deficiency stress. The extension of phytosiderophore in the rhizosphere soil is found only within 1 mm apart from the root surface. The rate of phytosiderophore secretion is negatively related to chlorophyll content in young leaves and positively related to the Fe-solubilizing capacity. Results from in vitro experiments show 10 μmoles mugineic acid can dissolve 501 μg Fe from iron hydroxide and 146 ug from strengite. Thus, phytosiderophore can considerably enhance the soil iron availability by increasing the solubility of amorphous iron hydroxide and iron phosphate, and active Fe is consequently accumulated in the plant rhizosphere , 43% higher than in the bulk soils. There is evidence to support that mugineic acid chelates with Fe3+at a rate of 1:1 in the acid condition. In addition ,we observe mugineic acid has certain effects on mobilization of P as well as Fe by dissolving the insoluble iron phosphate. And phytosiderophore seems to be an effective remedy for the chlorosis of dicotyledonous plants.
