The mixed forests of the upper Rio Negro at the northern of the Amazon basin grow in oxisol soils that are extremely infertile. These areas exhibit deficiencies in several macro-nutrients, and may also be characterize...The mixed forests of the upper Rio Negro at the northern of the Amazon basin grow in oxisol soils that are extremely infertile. These areas exhibit deficiencies in several macro-nutrients, and may also be characterized by the shortage or toxic excess of some micronutrients. The overall goal of this research is to collect more comprehensive information regarding the micronutrient composition of the upper Rio Negro forests as well as discern the relationship between leaf micro- and macro-nutrients that may contribute to the homeostasis and balance of the ionome. Firstly, the nutrient composition within the oxisol soil and leaf tissues of two top canopy tree species from the mixed forests was determined. We then analyzed the relationship between leaf micronutrient composition with N and P levels of the two species and that of species inhabiting the Amazon caatinga. Extractable soil Zn, B, Mn and Cu were very low in the mixed forest. In contrast, Fe and Al levels were potentially toxic. The analysis of leaf N/P ratios revealed for the first time the co-limitation of N and P in the mixed forest. This contrasts with species from the adjacent Amazon caatinga toposequence that are characterized by strong N limitation. All micronutrients within leaves of species inhabiting the mixed forest were also found to have low concentrations. Moreover, Fe and Al were detected at concentrations well below those reported for accumulator species. This suggested that leaf ion homeostasis was maintained under potentially toxic soil Fe and Al conditions. Leaf micronutrient (Fe, Zn and B) contents mirrored that of leaf N and P contents, and comparable Fe/N, Fe/P, Zn/N, Zn/P, B/N as well as B/P ratios were found across species and forest types. Therefore, forest species exhibited the capability to maintain leaf nutrient balances under soil conditions with deficient or toxic levels of micronutrients.展开更多
Cowpea, string Bean, or Macassar bean [Vigna unguiculata (L.) Walp] presents a short life cycle, low water requirement, develops in soils of low fertility, and has the ability to fix nitrogen from the air. In the Cerr...Cowpea, string Bean, or Macassar bean [Vigna unguiculata (L.) Walp] presents a short life cycle, low water requirement, develops in soils of low fertility, and has the ability to fix nitrogen from the air. In the Cerrado, the oxisols occupy practically all the flat to soft-wavy areas with little reserve of nutrients for the plants, in general, they are soils with great limitations of fertility. A source of alternative phosphate fertilization is the use of reactive natural phosphates. The reactive natural phosphate of Bayóvar presents intermediate solubility between the sources of soluble phosphates and the natural phosphates. In this context, the objective was to evaluate the initial development of Cowpea beans fertilized with the natural Bayóvar phosphate used for cultivation of the Brazilian Cerrado Oxisol. The experimental design was completely randomized, with six doses of phosphorus (0, 100, 200, 300, 400, 500 mg·dm-3) using natural Bayovar phosphate as a source in four replications. The species used in this study was the legume cowpea bean [Vigna unguiculata (L.) Walp] cultivar Tumucumaque. The treatments were applied using the natural phosphate Bayóvar as a source of phosphorus (29% of P2O5). At 33 DAS (days after sowing), the variable number of leaves of the Cowpea bean was analyzed and at 40 DAS, the variables plant height, SPAD chlorophyll index (Soil Plant Analysis Development) and stem diameter were analyzed. For all variables analyzed there was a significant effect. The initial development of the cowpea bean cultivated in the Brazilian Cerrado Oxisol was significantly influenced by the Bayóvar natural phosphate fertilization with the best phosphorus (P2O5) doses in the range of 200 to 350 mg·展开更多
A major nutritional problem to crops grown in highly weathered Brazilian soils is phosphorus (P) deficiencies linked to their low availability and the capacity of the soils to fix P in insoluble forms. Our studies exa...A major nutritional problem to crops grown in highly weathered Brazilian soils is phosphorus (P) deficiencies linked to their low availability and the capacity of the soils to fix P in insoluble forms. Our studies examined factors that might influence P behavior in soils of the Amazon region. This study was conducted to evaluate the maximum phosphate adsorption capacity (MPAC) of the soils developed from mafic rocks (diabase), their parent materials and other factors resulting in the formation of eutrophic soils having A chernozemic horizon associated with Red Nitosols (Alfisol) and Red Latosols (Oxisol) of the Amazonian environment. The MPAC was determined in triplicates as a function of the remnant P values. The different concentrations used to determine the MPAC allowed maximum adsorption values to be reached for all soils. The Latosol (Oxisol) and Nitosol (Alfisol) soils presented higher phosphate adsorption values that were attributed to the oxidic mineralogy and high clay texture while the Chernosol (Mollisol) soils presented the lowest phosphate adsorption values.展开更多
To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using c...To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, Al adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of Al above a certain initial Al concentration (0.1 mmol L-1 for kaolinite and 0.3 mmol L-1 for the Oxisol). The Al hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of Al and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of Al hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. Al hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in Al adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed Al3+ in total adsorbed Al with the increase in soil negative surface charge and eliminated or reduced the acceleration of Al hydrolysis. Different organic anions inhibited the hydrolysis of Al in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al.展开更多
In the present work, the adsorption of sulfate and fluoride by two oxisols was studied, and during the adsorption OH- released from soils were measured and the change in surface charge carried by one of the soils afte...In the present work, the adsorption of sulfate and fluoride by two oxisols was studied, and during the adsorption OH- released from soils were measured and the change in surface charge carried by one of the soils after the adsorption of fluoride was examined. The results show that the adsorption of sulfate by oxisols and the release of OH- from oxisols both increased with the increase of sulfate added at a constant pH, but decreased when pH became higher gradually. The adsorption and release both decreased markedly after removal of iron oxide. The ratio of OH- to SO42- for Fe-removed soils decreased to 15-34% of the original soils. These results suggest that iron oxide was the chief carrier of hydroxyl groups capable of ligand exchange with sulfate in oxisols.Compared with sulfate, however, the amount of fluoride adsorbed, OH- released during the adsorption of fluoride and the ratio of OH- to F- were much larger. The effect of iron oxide on the adsorption of fluoride by oxisols was smaller than that on the adsorption of sulfate. The ratios of OH- to F- for an oxisol from Brazil were 0.62 and 0.48 respectively before and after removal of free iron oxides. This implied that iron oxide only provided a small amount of exchangeable hydroxyl groups capable of ligand exchange with fluoride in oxisol. The research results indicate that among the factors inducing the changes in some properties of oxisols after adsorption of fluoride, the role became less important in the sequence of the release of OH-> the increase of negative charge > the decrease of positive charge.展开更多
Many Hawaiian agricultural soils are acidic with low-nutrient retention;therefore,organic soil amendments are often used to improve soil properties and increase yields.Amendments can be incorporated for annual crops,b...Many Hawaiian agricultural soils are acidic with low-nutrient retention;therefore,organic soil amendments are often used to improve soil properties and increase yields.Amendments can be incorporated for annual crops,but perennial orchards need surface application to avoid damaging surface roots.Pot trials compared responses to incorporated(IBC)or surface-applied(SBC)combination of hardwood biochar and chicken manure compost(4%v/v of each amendment)added to an Andisol and Oxisol.Soil pH was increased by 0.4-1.1 units in IBC and by 0.2-0.5 for SBC in the 0-10 cm soil layer.Both SBC and IBC increased soil total N,extractable P,Ca and Mg in the 0-10 cm soil layer.Soil pH,total C and extractable Ca were also higher in the 10-20 cm soil layer for IBC soil,indicating movement and/or leaching of amendments.Chinese cabbage biomass was 18-70%higher in the IBC and 14-47%higher in the SBC than that in the unamended soil,while papaya biomass was 23%and 19%higher in SBC and IBC,respectively.There was a greater response in the more acidic Andisol soil,with larger improvements in soil pH,plant nutrient uptake and root biomass than the Oxisol.Surface application was as effective in increasing plant growth as the incorporated amendment,providing evidence for farm scale assessment.Biochar and compost are recommended for use in tropical soils,and surface application may be beneficial to annual and perennial crops.展开更多
文摘The mixed forests of the upper Rio Negro at the northern of the Amazon basin grow in oxisol soils that are extremely infertile. These areas exhibit deficiencies in several macro-nutrients, and may also be characterized by the shortage or toxic excess of some micronutrients. The overall goal of this research is to collect more comprehensive information regarding the micronutrient composition of the upper Rio Negro forests as well as discern the relationship between leaf micro- and macro-nutrients that may contribute to the homeostasis and balance of the ionome. Firstly, the nutrient composition within the oxisol soil and leaf tissues of two top canopy tree species from the mixed forests was determined. We then analyzed the relationship between leaf micronutrient composition with N and P levels of the two species and that of species inhabiting the Amazon caatinga. Extractable soil Zn, B, Mn and Cu were very low in the mixed forest. In contrast, Fe and Al levels were potentially toxic. The analysis of leaf N/P ratios revealed for the first time the co-limitation of N and P in the mixed forest. This contrasts with species from the adjacent Amazon caatinga toposequence that are characterized by strong N limitation. All micronutrients within leaves of species inhabiting the mixed forest were also found to have low concentrations. Moreover, Fe and Al were detected at concentrations well below those reported for accumulator species. This suggested that leaf ion homeostasis was maintained under potentially toxic soil Fe and Al conditions. Leaf micronutrient (Fe, Zn and B) contents mirrored that of leaf N and P contents, and comparable Fe/N, Fe/P, Zn/N, Zn/P, B/N as well as B/P ratios were found across species and forest types. Therefore, forest species exhibited the capability to maintain leaf nutrient balances under soil conditions with deficient or toxic levels of micronutrients.
文摘Cowpea, string Bean, or Macassar bean [Vigna unguiculata (L.) Walp] presents a short life cycle, low water requirement, develops in soils of low fertility, and has the ability to fix nitrogen from the air. In the Cerrado, the oxisols occupy practically all the flat to soft-wavy areas with little reserve of nutrients for the plants, in general, they are soils with great limitations of fertility. A source of alternative phosphate fertilization is the use of reactive natural phosphates. The reactive natural phosphate of Bayóvar presents intermediate solubility between the sources of soluble phosphates and the natural phosphates. In this context, the objective was to evaluate the initial development of Cowpea beans fertilized with the natural Bayóvar phosphate used for cultivation of the Brazilian Cerrado Oxisol. The experimental design was completely randomized, with six doses of phosphorus (0, 100, 200, 300, 400, 500 mg·dm-3) using natural Bayovar phosphate as a source in four replications. The species used in this study was the legume cowpea bean [Vigna unguiculata (L.) Walp] cultivar Tumucumaque. The treatments were applied using the natural phosphate Bayóvar as a source of phosphorus (29% of P2O5). At 33 DAS (days after sowing), the variable number of leaves of the Cowpea bean was analyzed and at 40 DAS, the variables plant height, SPAD chlorophyll index (Soil Plant Analysis Development) and stem diameter were analyzed. For all variables analyzed there was a significant effect. The initial development of the cowpea bean cultivated in the Brazilian Cerrado Oxisol was significantly influenced by the Bayóvar natural phosphate fertilization with the best phosphorus (P2O5) doses in the range of 200 to 350 mg·
文摘A major nutritional problem to crops grown in highly weathered Brazilian soils is phosphorus (P) deficiencies linked to their low availability and the capacity of the soils to fix P in insoluble forms. Our studies examined factors that might influence P behavior in soils of the Amazon region. This study was conducted to evaluate the maximum phosphate adsorption capacity (MPAC) of the soils developed from mafic rocks (diabase), their parent materials and other factors resulting in the formation of eutrophic soils having A chernozemic horizon associated with Red Nitosols (Alfisol) and Red Latosols (Oxisol) of the Amazonian environment. The MPAC was determined in triplicates as a function of the remnant P values. The different concentrations used to determine the MPAC allowed maximum adsorption values to be reached for all soils. The Latosol (Oxisol) and Nitosol (Alfisol) soils presented higher phosphate adsorption values that were attributed to the oxidic mineralogy and high clay texture while the Chernosol (Mollisol) soils presented the lowest phosphate adsorption values.
基金Project supported by the National Natural Science Foundation of China (No. 40271062).
文摘To evaluate the role of kaolinite and variable charge soils on the hydrolytic reaction of Al, the hydrolysis of Al ions in suspensions of a kaolinite and an Oxisol influenced by organic anions was investigated using changes of pH, Al adsorption, and desorption of pre-adsorbed Al. Kaolinite and the Oxisol promoted the hydrolytic reaction of Al above a certain initial Al concentration (0.1 mmol L-1 for kaolinite and 0.3 mmol L-1 for the Oxisol). The Al hydrolysis accelerated by kaolinite and the Oxisol increased with an increase in initial concentration of Al and was observed in the range of pH from 3.7 to 4.7 for kaolinite and 3.9 to 4.9 for the Oxisol. The acceleration of Al hydrolysis also increased with the increase of solution pH, reached a maximum value at pH 4.5, and then decreased sharply. Al hydrolysis was promoted mainly through selective adsorption for hydroxy-Al. Soil free iron oxides compensated a portion of the soil negative charge or masked some soil surface negative sites leading to a decrease in Al adsorption, which retarded acceleration to some extent. For the Oxisol organic anions increased the proportion of adsorbed Al3+ in total adsorbed Al with the increase in soil negative surface charge and eliminated or reduced the acceleration of Al hydrolysis. Different organic anions inhibited the hydrolysis of Al in the order: citrate > oxalate > acetate (under initial pH of 4.5). The formation of Al-organic complexes in solution also inhibited the hydrolysis of Al.
文摘In the present work, the adsorption of sulfate and fluoride by two oxisols was studied, and during the adsorption OH- released from soils were measured and the change in surface charge carried by one of the soils after the adsorption of fluoride was examined. The results show that the adsorption of sulfate by oxisols and the release of OH- from oxisols both increased with the increase of sulfate added at a constant pH, but decreased when pH became higher gradually. The adsorption and release both decreased markedly after removal of iron oxide. The ratio of OH- to SO42- for Fe-removed soils decreased to 15-34% of the original soils. These results suggest that iron oxide was the chief carrier of hydroxyl groups capable of ligand exchange with sulfate in oxisols.Compared with sulfate, however, the amount of fluoride adsorbed, OH- released during the adsorption of fluoride and the ratio of OH- to F- were much larger. The effect of iron oxide on the adsorption of fluoride by oxisols was smaller than that on the adsorption of sulfate. The ratios of OH- to F- for an oxisol from Brazil were 0.62 and 0.48 respectively before and after removal of free iron oxides. This implied that iron oxide only provided a small amount of exchangeable hydroxyl groups capable of ligand exchange with fluoride in oxisol. The research results indicate that among the factors inducing the changes in some properties of oxisols after adsorption of fluoride, the role became less important in the sequence of the release of OH-> the increase of negative charge > the decrease of positive charge.
基金funded through Western Sustainable Agriculture Research and Education(SARE),USDA(for NV Hue and A Ahmad)。
文摘Many Hawaiian agricultural soils are acidic with low-nutrient retention;therefore,organic soil amendments are often used to improve soil properties and increase yields.Amendments can be incorporated for annual crops,but perennial orchards need surface application to avoid damaging surface roots.Pot trials compared responses to incorporated(IBC)or surface-applied(SBC)combination of hardwood biochar and chicken manure compost(4%v/v of each amendment)added to an Andisol and Oxisol.Soil pH was increased by 0.4-1.1 units in IBC and by 0.2-0.5 for SBC in the 0-10 cm soil layer.Both SBC and IBC increased soil total N,extractable P,Ca and Mg in the 0-10 cm soil layer.Soil pH,total C and extractable Ca were also higher in the 10-20 cm soil layer for IBC soil,indicating movement and/or leaching of amendments.Chinese cabbage biomass was 18-70%higher in the IBC and 14-47%higher in the SBC than that in the unamended soil,while papaya biomass was 23%and 19%higher in SBC and IBC,respectively.There was a greater response in the more acidic Andisol soil,with larger improvements in soil pH,plant nutrient uptake and root biomass than the Oxisol.Surface application was as effective in increasing plant growth as the incorporated amendment,providing evidence for farm scale assessment.Biochar and compost are recommended for use in tropical soils,and surface application may be beneficial to annual and perennial crops.
