Assessment, regionalization, and modeling rainfall erosivity over Brazil: Findings from a large national database.

In this study, we used a large national database to assess the rainfall erosivity (RE) patterns in time and space over the Brazilian territory. Thereby, RE and erosivity density (ED) values were obtained for 5166 rainfall gauges. Also, the concentration of the RE throughout the year and the RE's gravity center locations were analyzed. Finally, homogeneous regions regarding RE values were delimited and estimative regression models were established. The results show that Brazil's mean annual RE value is 5620 MJ mm ha-1 h-1 year-1, with considerable spatial variation over the country. The highest RE magnitudes were found for the north region, while the northeast region shows the lowest values. Regarding the RE's distribution throughout the year, in the southern region of Brazil, it is more equitable, while in some spots of the northeastern region, it is irregularly concentrated in specific months. Further analyses revealed that for most of the months, the RE's gravity centers for Brazil are in the Goiás State and that they present a north-south migration pattern throughout the year. Complementarily, the ED magnitudes allowed the identification of high-intensity rainfall spots. Additionally, the Brazilian territory was divided into eleven homogeneous regions regarding the RE patterns and for each defined region, a regression model was established and validated. These models' statistical metrics were considered satisfactory and, thus, can be used to estimate RE values for the whole country using monthly rainfall depths. Finally, all database produced are available for download. Therefore, the values and maps shown in this study are relevant for improving the accuracy of soil loss estimates in Brazil and for the establishment of soil and water conservation planning on a national scale.

Random forest for spatialization of daily evapotranspiration (ET0) in watersheds in the Atlantic Forest.

The importance of daily data on reference evapotranspiration (ET0) has increased in recent years due to its relevance in planning and decision making regarding irrigated agriculture, water production, and forest restoration. Facing the scarcity of this information measured in loco, the study of interpolation methods capable of representing ET0 becomes important. Therefore, this study aimed to evaluate the adequacy of the Random Forest (RF) method in the spatialization of ET0 in the watersheds of the Mid-South region of the Espírito Santo State, located within the Atlantic Forest biome, Brazil. From this study, it was found that the RF method is the most suitable one for ET0 spatialization when compared to the Angular distance weighting (ADW) and the inverse distance weighting (IDW) techniques. Also, the spatializations carried out by this method were transformed into databases in a grid format and made available online. Furthermore, the RF database was also compared to other ET0 grid databases, and it was concluded that the RF database also carried out a better performance than the other ones.

Qualidade da água de nascentes do Assentamento Paraíso / Quality of the water from the springs of the Paraíso settlement

RESUMO Este estudo teve por objetivo avaliar a influência de diferentes usos do solo no entorno de nascentes sobre alguns parâmetros de qualidade das águas de oito nascentes localizadas no Assentamento Paraíso, Alegre, Espírito Santo. As nascentes avaliadas consistiram em uma em meio à floresta remanescente de Mata Atlântica; seis cercadas e em diferentes estágios de recomposição florestal; e uma sem cerca e com acesso livre dos animais de criação. Três amostras de água foram coletadas em cada nascente entre 2011 e 2012, sendo analisados 17 parâmetros. Os valores determinados foram comparados com os padrões normativos para qualidade da água e correlacionados linearmente por meio do coeficiente de correlação. As águas das nascentes se mostraram aptas para o consumo, desde que previamente tratadas, e, quanto maior foram os trabalhos de proteção às nascentes, melhores foram os valores de qualidade de água.

ABSTRACT The objective of this study was to evaluate the influence of land use in the surrounding of the springs on some of the parameters of water quality in eight springs located in the Paraíso settlement in the city of Alegre, Espírito Santo, Brazil. The springs evaluated were: one in the Atlantic forest remnant; six fenced ones and in different stages of forest recovery; and one without a fence and with free livestock access. Three samples of water were collected in each spring in 2011 and 2012, and 17 parameters were analyzed. The determined values were compared to the normative standards for water quality and linearly correlated through the correlation coefficient. Water from the springs showed to be consumable, if previously treated, and the more protected the springs, the better the water quality values.

Massa seca e extração de nutrientes por duas forrageiras fertirrigadas com esgoto doméstico tratado / Dry mass and nutrient extraction of two forage fertigated with domestic sewage treated

Devido à pouca informação sobre a capacidade de extração de nutrientes do solo por forrageiras fertirrigadas com efluentes, o presente trabalho teve como objetivo avaliar a capacidade de extração de macronutrientes e sódio do solo pelas forrageiras Tifton 85 (Cynodon spp) e Capim Marandú (Brachiaria brizantha) fertirrigadas com esgoto doméstico tratado em três ciclos de produção, em condições de casa de vegetação. Os experimentos foram montados num delineamento inteiramente casualizado, sendo um para cada espécie, ambos no esquema em parcelas subdivididas 4x3 com 5 repetições, sendo quatro ratamentos fertirrigados com esgoto doméstico tratado nas dosagens de 20, 40, 60 e 80 kg ha-1 de nitrogênio nas parcelas e nas subparcelas, três ciclos de produção onde foram realizados cortes no material vegetal das forrageiras, sempre aos 30 dias após o término da aplicação do esgoto doméstico tratado. Após cada corte, os tratamentos foram novamente aplicados e no material vegetal cortado foram quantificados os teores foliares dos macronutrientes e sódio extraídos do solo pelas forrageiras. Os resultados obtidos demonstraram que a aplicação de nitrogênio por meio do esgoto doméstico tratado e os ciclos de produção (cortes) afetaram positivamente a produção de massa seca e a extração dos macronutrientes e sódio pelas plantas de Tifton 85 e de Capim Marandú.

Due to limited information on the ability to extract nutrients from the soil by forage fertigated with effluent, the present study aimed to evaluate the extraction capacity of soil macronutrients and sodium by fodder Tifton 85 (Cynodon spp) and Marandu Grass (Brachiaria brizantha) fertigated with treated domestic sewage on three production cycles in greenhouse conditions. The experiments were performed in a completely randomized design, one for each species, both in split plot layout 4x3 with 5 repetitions, four fertigation with treated domestic sewage at dosages of 20, 40, 60 and 80 kg ha-1 nitrogen in plots and subplots, three production cycles where cuts were made in the forage plant material, always 30 days after the completion of the application of treated domestic sewage. After each cut, the treatments were applied again and cut plant material were quantified foliar levels and sodium extracted from the soil by forage. The results showed that the application of nitrogen through the treated domestic sewage and production cycles (cuts) positively affected the dry matter production and extraction of macronutrients and sodium by plants and Tifton 85 on the Marandú Grass.

Avaliação de alguns atributos físicos de um latossolo vermelho-amarelo sob diferentes coberturas vegetais / Evaluation of some physical attributes of an oxisol under different crop cover

Os atributos do solo são dinâmicos e estão sujeitos a alterações de acordo com o uso e manejo adotado, sendo sua determinação importante para melhor utilização agrícola dos solos. Desta forma, objetivou-se avaliar o comportamento de alguns atributos físicos (composição granulométrica, argila dispersa em água e grau de floculação) de um Latossolo Vermelho-Amarelo sobre diferentes usos, a saber: cultivado com duas espécies de leguminosas e sob vegetação espontânea, em área anteriormente cultivada com horticultura, por aproximadamente 10 anos, sob intensa mecanização agrícola e aplicação de corretivos e fertilizantes. O experimento foi instalado no delineamento em blocos casualizados, sendo conduzido em esquema fatorial 2 x 3, sendo duas profundidades (0 a 20 e 20 a 40 cm) e três coberturas vegetais (duas leguminosas e uma vegetação espontânea) com 4 repetições cada. Os dados das avaliações foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey a 5% de probabilidade. Observou-se que a agitação lenta proporciona uma melhor dispersão física quando comparada com a agitação rápida, demonstrando maior acurácia e precisão. Os valores de argila dispersa em água são maiores na profundidade de 20-40 cm. O solo cultivado com mucuna preta, na profundidade de 20-40 cm, apresenta um maior valor de argila dispersa em água em relação às demais coberturas vegetais e o solo sob vegetação espontânea maior grau de floculação nesta profundidade.

Soil attributes are dynamic and are subject to change according to the use and management adopted, is important for determining its best use agricultural soil. Thus, it was aimed to evaluate some physical attributes (particle size, water dispersible clay and flocculation) of an Oxisol on different uses, namely: cultivated with two species of legumes and natural vegetation, in an area previously cultivated with vegetables, for about 10 years, under intense agricultural mechanization and application of lime and fertilizer. The experiment was conducted in a randomized block design, being conducted in factorial 2 x 3, two depths (0 to 20 and 20 to 40 cm) and three cover crops, with four replications. Data were submitted to analysis of variance and averages compared by Tukey test at 5% probability. It was Avaliação de alguns atributos... SANTOS, L. N. S. et al. Biosci. J., Uberlândia, v. 26, n. 6, p. 940-947, Nov./Dec. 2010 946 observed that the slow agitation provides better physical dispersion when compared with the fast agitation, showing greater accuracy and precision. The values of clay dispersed in water are larger at a depth of 20-40 cm. The soil under Mucuna pruriens L., in depth of 20-40 cm, has a higher value of water dispersible clay in water compared with to other cover crops and the soil under natural vegetation greater degree of flocculation this depth