The legume-rhizobia relationship is an important symbiosis. Studies have found variation in specificity and the functionality of symbiotic specificity can vary among plants of the same species and among rhizobia, as well as in concert with geographical variation. Here, we examined the diversity and geographic structure of rhizobia nodulating Chamaecrista fasciculata, which grows throughout the east-central U.S. and is symbiotic with Bradyrhizobium species. We investigated the association of geography and soil variables on rhizobial diversity by sampling plant nodules and soil across Mississippi and evaluated variation in rhizobia housed in different nodules of individual plants. Using nifH and truA, we conducted phylogenetic analyses and mantel tests but did not find that geography correlates with genetic diversity. However, soil variables and genetic distance were significantly correlated. Lastly, we found that rhizobia across nodules of the same plant varied substantially. These results contribute to the knowledge of rhizobial assemblages in natural populations.

Infiltration, the process of water movement through the soil surface is one of most important hydrological processes to be considered in watershed management. The process depends on rainfall, soil, vegetation and topographic conditions. The last three variables can be influenced by human land-uses. This study is concerned with the influence of landuse types (categories) on infiltration at the upper Ciliwung watershed of West-Java, Indonesia. Sixty six infiltration measurements were carried out in 5 types of land-uses i.e. natural forest, agriculture, settlement, productive (old) tea and new tea plantation areas. The measurements were done using ring infiltrometers. The data obtained were expressed in the form of Philip's equation I = st1I2 + At, where I is cumulative infiltration; S is sorptivity; t is time; A is a parameter which was calculated from saturated hydraulic conductivity (K). Crown cover, slope gradient and soil variables such as soil moisture, organic carbon content, total porosity, bulk density were also analysed from each of the 66 sites. The results of the study shows that land-use types have significant influence on these soil variables and on infiltration. Crown cover and human activities in term of land management are among the most important factors which affect soil condition. These variables mostly influence total porosity of soil which is the most important variable to determine sorptivity and hydraulic conductivity. High percentage of crown cover and less human activity in forest area result in high accumulation of litter and humus and high total porosity of soil. On the other hand, settlement and new tea plantation areas have comparatively low crown cover and more frequent human activity which result in soil compaction. Discriminant function analysis of land-use categories shows that the soil under forest is very distinct from the soils under other land-use types. However, the soils under the remaining land-use types are more similar to each other, especially between the soil of settlement and tea plantations. The rank of infiltration rate from the highest to the lowest magnitude is as follows; natural forest, agriculture, productive tea plantation, new tea plantation and settlement areas. Infiltration rates under natural forest and agriculture are significantly different from each other as well as from those in the last three land- use types. However, there are no significant differences in infiltration rates among the last three land-use types. The result of this study also provides basic information for landuse management and further research in order to solve soil and water conservation and management problems in the watershed.

Objetivou-se neste trabalho avaliar a variabilidade espacial e temporal do carbono no solo produzindo um mapa, sobre esse tema para toda a área da Estação Experimental de Mogi Mirim (EE Mogi Mirim), juntamente com a análise dos fluxos dos gases de efeito estufa (CO2, N2O e CH4) e a relação desses dois fenômenos com as variáveis do solo nos diferentes usos da terra. Para se alcançar objetivo proposto com relação aos estoques de carbono e avaliação das variáveis do solo foi feita a coleta e o prepara das amostras nas profundidades de 00 até 30 cm, foi feito o georreferenciamento e determinação dos teores de carbono, densidade do solo, calculo dos estoques de carbono e determinação da cor do solo. Por sua vez para o estudo e entendimento dos fluxos dos gases de efeito estufa (GEE), comparou-se um talhão considerado sem perturbação (Talhão 41) e a partir desse talhão avaliou-se comparativamente em uma seqüência com ambientes com histórico de uso da terra representativo da área com manejos. Os fluxos dos gases CO2, N2O e CH4 foram medidos utilizando-se câmaras estáticas. Nos resultados obtidos foi aplicada a estatística descritiva clássica e geoestatistica para avaliar a freqüência e distribuição dos dados. Resultados relativos as variáveis do solo mostram que praticamente a grande maioria tende a diminuir com a profundidade (Ca, soma das bases, CTC, acidez potencial e carbono). Por sua vez o pH é sempre muito alto nas 3 camadas e a saturação por bases e o magnésio são muito baixos e permanecem inalterados em todas as profundidades. A variabilidade espacial dos estoques de carbono possui características isotrópicas. Especificamente na profundidade 00 - 10 cm, o modelo teórico que melhor se ajustou foi o exponencial, na profundidade 10 - 20 cm foi o esférico e na profundidade 20 - 30 cm foi o exponencial. Os estoque de C na profundidade 00 10 cm, tiveram como média 22.8 ton C/ ha-1, sendo o maior valor de 42.9 ton C/há-1 e o menor valor de 10.3 ton C/há-1. Na profundidade 10 - 20cm, a média do estoque de carbono foi de 14.9 ton C/há-1, sendo o maior valor de 31.5 ton C/há-1 e o menor valor de 6.99 ton C/há-1. Na profundidade 20 -30 cm, a média do estoque de carbono foi de 11.45 ton C/há-1, sendo o maior valor de 25.28 ton C/há-1 e o menor valor de 6.3 ton C/há-1. Os resultados das análises dos fluxos do gás carbônico, como um todo mostra que a respiração do solo variou entre 75.3 e 164.4mgC m-2 h-1. Relativo aos fluxos de N2O os valores médios para as emissões variaram entre 8,85 e 51,94 \'mü\'gN m-2 h-1, enquanto que a absorção variou, entre -1,32 e - 4,59 \'mü\'gN m-2 h-1. Os resultados dos fluxos do gás metano médio ficaram entre 4,63 e 31,51 mgC m-2 h-1, enquanto que os valores de oxidação média ficaram entre -5,41 e -22,79 mgC m-2 h-1 / The aim here is to evaluate the spacial and transient variability of carbon in soil, producing a map about this subject for all the area of the Experimental Station of Mogi Mirim (Estação Experimental de Mogi Mirim EE Mogi Mirim), with the emissions analyzes of greenhouse gases effect (CO2, N2O e CH4), and the relation between these phenomenon with the soil variables in different uses of the land. In order to reach the proposed objective related to the carbon storages, and the variable evaluation of the soil, a sample collect and preparation were made at a depth from 00 to 30cm. It was also made the georeferencial and the carbon levels determination, density of soil, the estimate of carbon storages, and the determination of soil color. The study and understanding of the greenhouse gas emissions (GGF), a área considered without disturbing, and from it a comparative evaluation in a sequence of environments with historical land use representative of the management area. The CO2, N2O and CH4 gas emissions were measured by using static chambers. In the results obtained, it was applied the classic statistic description and geostatistics to evaluate the frequency and the distribution of data. Results related to the soil variables show that the major trend to decrease, according to the depth (Ca, sum of bases, CTC, potential acidity, and carbon). On the contrary, the pH is always very high in 3 layers, and the saturation for bases and the magnesium are very low, maintaining unchangeable in all depths. The variability of the carbon storages have isotropic characteristics. Specifically in depth 00 - 10cm, the theorical model that better adjusted was the exponential; in depth 10 - 20cm, it was the spherical, and in depth 20 - 30cm it was the exponential. The carbon storage in depth 00-10cm had as na average 22.8ton C / ha-1, being the highest value of 42.9 ton C/ha-1, and the lowest value of 10.3 ton C/ha-1. In depth 10 - 20 cm, the average of carbon storage was 14.9 ton C/ha-1, being the highest value of 31.5 ton C/ha-1, and the lower value of 6.99 ton C/ha-1. In depths of 20 - 30cm, the average of carbon storage was of 11.45 ton C/há-1, being the highest value of 25.28 ton C/ha-1, and the lowest of 6.3 ton C/ha-1 The analyze results of carbon gás emissions as a whole, shows that the soil breath varied between 75.3 e 164.4 . mgC m-2 h-1 . Regard to N2O emissions, the average values to emissions varied between 8.85 and 51.94 \'mü\'gN m-2 h-1, while the absorption varied, between -1.32 e - 4.59 \'mü\'gN m-2 h-1. The results of average methane gas were between 4.63 e 31.51 mgC m-2 h-1, while the average oxidation values were between -5.41 e -22.79 mgC m-2 h-1

Objetivou-se neste trabalho avaliar a variabilidade espacial e temporal do carbono no solo produzindo um mapa, sobre esse tema para toda a área da Estação Experimental de Mogi Mirim (EE Mogi Mirim), juntamente com a análise dos fluxos dos gases de efeito estufa (CO2, N2O e CH4) e a relação desses dois fenômenos com as variáveis do solo nos diferentes usos da terra. Para se alcançar objetivo proposto com relação aos estoques de carbono e avaliação das variáveis do solo foi feita a coleta e o prepara das amostras nas profundidades de 00 até 30 cm, foi feito o georreferenciamento e determinação dos teores de carbono, densidade do solo, calculo dos estoques de carbono e determinação da cor do solo. Por sua vez para o estudo e entendimento dos fluxos dos gases de efeito estufa (GEE), comparou-se um talhão considerado sem perturbação (Talhão 41) e a partir desse talhão avaliou-se comparativamente em uma seqüência com ambientes com histórico de uso da terra representativo da área com manejos. Os fluxos dos gases CO2, N2O e CH4 foram medidos utilizando-se câmaras estáticas. Nos resultados obtidos foi aplicada a estatística descritiva clássica e geoestatistica para avaliar a freqüência e distribuição dos dados. Resultados relativos as variáveis do solo mostram que praticamente a grande maioria tende a diminuir com a profundidade (Ca, soma das bases, CTC, acidez potencial e carbono). Por sua vez o pH é sempre muito alto nas 3 camadas e a saturação por bases e o magnésio são muito baixos e permanecem inalterados em todas as profundidades. A variabilidade espacial dos estoques de carbono possui características isotrópicas. Especificamente na profundidade 00 - 10 cm, o modelo teórico que melhor se ajustou foi o exponencial, na profundidade 10 - 20 cm foi o esférico e na profundidade 20 - 30 cm foi o exponencial. Os estoque de C na profundidade 00 10 cm, tiveram como média 22.8 ton C/ ha-1, sendo o maior valor de 42.9 ton C/há-1 e o menor valor de 10.3 ton C/há-1. Na profundidade 10 - 20cm, a média do estoque de carbono foi de 14.9 ton C/há-1, sendo o maior valor de 31.5 ton C/há-1 e o menor valor de 6.99 ton C/há-1. Na profundidade 20 -30 cm, a média do estoque de carbono foi de 11.45 ton C/há-1, sendo o maior valor de 25.28 ton C/há-1 e o menor valor de 6.3 ton C/há-1. Os resultados das análises dos fluxos do gás carbônico, como um todo mostra que a respiração do solo variou entre 75.3 e 164.4mgC m-2 h-1. Relativo aos fluxos de N2O os valores médios para as emissões variaram entre 8,85 e 51,94 \'mü\'gN m-2 h-1, enquanto que a absorção variou, entre -1,32 e - 4,59 \'mü\'gN m-2 h-1. Os resultados dos fluxos do gás metano médio ficaram entre 4,63 e 31,51 mgC m-2 h-1, enquanto que os valores de oxidação média ficaram entre -5,41 e -22,79 mgC m-2 h-1 / The aim here is to evaluate the spacial and transient variability of carbon in soil, producing a map about this subject for all the area of the Experimental Station of Mogi Mirim (Estação Experimental de Mogi Mirim EE Mogi Mirim), with the emissions analyzes of greenhouse gases effect (CO2, N2O e CH4), and the relation between these phenomenon with the soil variables in different uses of the land. In order to reach the proposed objective related to the carbon storages, and the variable evaluation of the soil, a sample collect and preparation were made at a depth from 00 to 30cm. It was also made the georeferencial and the carbon levels determination, density of soil, the estimate of carbon storages, and the determination of soil color. The study and understanding of the greenhouse gas emissions (GGF), a área considered without disturbing, and from it a comparative evaluation in a sequence of environments with historical land use representative of the management area. The CO2, N2O and CH4 gas emissions were measured by using static chambers. In the results obtained, it was applied the classic statistic description and geostatistics to evaluate the frequency and the distribution of data. Results related to the soil variables show that the major trend to decrease, according to the depth (Ca, sum of bases, CTC, potential acidity, and carbon). On the contrary, the pH is always very high in 3 layers, and the saturation for bases and the magnesium are very low, maintaining unchangeable in all depths. The variability of the carbon storages have isotropic characteristics. Specifically in depth 00 - 10cm, the theorical model that better adjusted was the exponential; in depth 10 - 20cm, it was the spherical, and in depth 20 - 30cm it was the exponential. The carbon storage in depth 00-10cm had as na average 22.8ton C / ha-1, being the highest value of 42.9 ton C/ha-1, and the lowest value of 10.3 ton C/ha-1. In depth 10 - 20 cm, the average of carbon storage was 14.9 ton C/ha-1, being the highest value of 31.5 ton C/ha-1, and the lower value of 6.99 ton C/ha-1. In depths of 20 - 30cm, the average of carbon storage was of 11.45 ton C/há-1, being the highest value of 25.28 ton C/ha-1, and the lowest of 6.3 ton C/ha-1 The analyze results of carbon gás emissions as a whole, shows that the soil breath varied between 75.3 e 164.4 . mgC m-2 h-1 . Regard to N2O emissions, the average values to emissions varied between 8.85 and 51.94 \'mü\'gN m-2 h-1, while the absorption varied, between -1.32 e - 4.59 \'mü\'gN m-2 h-1. The results of average methane gas were between 4.63 e 31.51 mgC m-2 h-1, while the average oxidation values were between -5.41 e -22.79 mgC m-2 h-1