RESUMO -A baixa disponibilidade de fósforo em solos ácidos, como os do Cerrado, exige um manejo eficiente da adubação fosfatada. O uso de tecnologias que aumentem a eficiência de uso do fósforo é uma alternativa que pode ser adotada, desde que se considere a realidade dos solos brasileiros. Este trabalho foi realizado com o objetivo de avaliar o efeito da aplicação de adubo fosfatado revestido com polímero, associada à calagem, na produção e parâmetros morfológicos da cultura do milho. O estudo foi conduzido em campo, em Latossolo Vermelho-Amarelo. O delineamento experimental foi em blocos ao acaso, arranjados em esquema fatorial 2 x 4, com três repetições. Os tratamentos resultaram da combinação de duas fontes de fósforo (MAP convencional e MAP revestido com polímero -Kimcoat ® ) com quatro níveis de saturação por bases (27; 40; 50 e 60%). As fontes de fósforo apresentaram diferenças dependentes dos níveis de saturação por bases. O MAP revestido com polímero promoveu melhor desempenho do milho, quanto à produtividade, produção de matéria seca total e altura de planta, em relação ao MAP convencional. As maiores diferenças foram verificadas nas saturações por bases de 40 e 50%, nas quais o MAP revestido promoveu o incremento na produtividade de grãos de 3,40 e 3,48 t ha -1 , respectivamente, em relação ao MAP convencional.Palavras-chave: Fósforo revestido. Adubação. Plantas-efeito do fósforo. ABSTRACT -The low availability of phosphorus in acid soils, such as those of the Cerrado, requires the efficient management of phosphorus fertilization. The use of technologies that increase the efficiency of phosphorus use is an alternative that can be adopted, provided the reality of Brazilian soils is taken into consideration. This work was carried out to evaluate the effect of polymer-coated phosphate fertilizer associated with liming on the production and morphological parameters of corn crops. The study was conducted in the field, in a red-yellow latosol. The experimental design was of randomized blocks arranged in a 2 x 4 factorial, with three replications. The treatments resulted from a combination of two sources of phosphorus (conventional MAP and polymer-coated MAP -Kimcoat ®) at four levels of saturation (27%, 40%, 50% and 60%). The sources of phosphorus displayed differences dependent on the base levels of saturation. The polymer-coated MAP improved the performance of corn, for productivity, total dry-matter yield and plant height, in relation to conventional MAP. The major differences were observed at base saturation levels of 40% and 50%, in which the coated MAP promoted an increase in grain yield of 3.40 and 3.48 t ha -1 , respectively, compared to conventional MAP.

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Several methods exist for determining soil organic carbon, and each one has its own advantages and limitations. Consequently, a comparison of the experimental results obtained when these methods are employed is hampered, causing problems in the comparison of carbon stocks in soils. This study aimed at evaluating the analytical procedures used in the determination of carbon and their relationships with soil mineralogy and texture. Wet combustion methods, including Walkley-Black, Mebius and Colorimetric determination as well as dry combustion methods, such as Elemental and Gravimetric Analysis were used. Quantitative textural and mineralogical (kaolinite, goethite and gibbsite) analyses were also carried out. The wet digestion methods underestimated the concentration of organic carbon, while the gravimetric method overestimated. Soil mineralogy interfered with the determination of carbon, with emphasis on the gravimetric method that was greatly influenced by gibbsite.

Differential protein profiles of three stages of somatic embryogenesis, including globular, torpedo, and cotyledonary somatic embryos, of Coffea arabica cv. Catuaí Vermelho were analyzed in an attempt to better understand somatic embryogenesis in coffee plants. Somatic embryos at these different stages of development were collected from in vitro-grown cultures, and then macerated in liquid nitrogen. Proteins were extracted with phenol and further quantified using the Bradford method. The bidimensional electrophoresis analysis revealed a wide range of proteins ranging between 10 and 160 kDa and of pH values ranging from 3 to 10. Several differentially expressed proteins were identified by mass spectrometry, and some were found to be specific to these different stages of somatic embryogenesis in coffee. The enolase and 11S storage globulin proteins, for example, could be used as molecular markers for somatic embryo development stages and for embryogenic and nonembryogenic genotype differentiation, respectively.

The nitrous oxide (N2O) emissions in agricultural systems are influenced by edaphoclimatic conditions, and the availability of soil organic matter (SOM) is a key factor. The objective of this study was to evaluate the accumulation of labile and stable SOM fractions and possible relations with N2O emissions using a multivariate approach in a 24‐year integrated crop–livestock experiment in the Cerrado region. The management systems consisted of: continuous cropping under no tillage (CC‐NT), continuous cropping under annual heavy disc harrow (CC‐CT), an integrated crop–livestock system under no tillage (CLS‐NT) and an adjacent area of native Cerrado as reference. The cumulative N2O emissions were quantified over a period of 146 days throughout the cultivation of sorghum (Sorghum bicolor (L.) Moench). Labile and stable soil carbon (C) fractions and C contents in classes of aggregates (macroaggregates >0.250 mm and microaggregates <0.250 mm) were determined. The cumulative N2O emissions were larger in the CC‐CT system, intermediate in the CC‐NT and CLS‐NT systems, and smaller in the Cerrado. The decomposition of crop residues during the crop succession (first and second crop seasons) and the presence of a grass forage (with grazing and not grazed) in both systems (CLS‐NT and CC‐NT, respectively) explain the differences in N2O fluxes between the land uses. Smaller cumulative N2O emissions were observed in the integrated system (CLS‐NT), which could be attributed to the greatest increase in soil C in its most stable SOM fractions (fulvic acid) and occlusion in microaggregates. This confirms the hypothesis that the accumulation of C in the most stable SOM fractions of the soil, unavailable to the microbiota, results in smaller N2O emissions. Principal component analysis also revealed that aggregation is a key attribute that correlates with soil N2O emissions. Thus, conservation systems such as CLS‐NT had larger average diameter of aggregates and the smallest N2O emissions among the agroecosystems. Highlights Relations between SOM fractions and N2O emissions were studied in integrated systems The accumulation of stabilized C fractions reduces N2O emissions Soil structure (aggregation) and SOM stability partially explain N2O fluxes Integrated crop–livestock promotes better soil conditions, reducing N2O emissions

R ESU M OA infiltração é o processo pelo qual a água penetra no solo através de sua superfície e sua dinâmica pode ser condicionada por diversos fatores, dentre eles os sistemas de manejo do solo adotados. O objetivo deste trabalho foi estimar a velocidade de infiltração da água e os teores de matéria orgânica do solo em sistema de consórcio milho e forrageiras. O experimento foi realizado em delineamento de blocos casualizados, com três repetições. Foram estudados os efeitos de cinco tratamentos submetidos ao manejo de plantio direto: 1) Milho Solteiro (Zea mays L.); 2) Braquiária Humidícola (Brachiaria humidicola); 3) Consórcio Milho e Braquiária Humidícola; 4) Capim Aruana (Panicum maximum cv. Aruana); 5) Consórcio Milho e Capim Aruana. Utilizou-se, para determinação da velocidade de infiltração básica (VIB), o método dos infiltrômetros de cilindros concêntricos. Outros atributos físicos do solo e a matéria orgânica do solo foram avaliados buscando-se associá-los aos valores de VIB encontrados. Os resultados revelaram que sob plantio direto os sistemas apresentaram elevados valores de VIB. O sistema Milho Solteiro apresentou a maior VIB e a inserção de forrageiras nos sistemas provocou redução da VIB; todos os sistemas apresentaram diminuição dos teores de matéria orgânica em profundidade. Palavras-chave : infiltrômetro, plantio direto, água no soloSoil organic matter and water infiltration under maize and forage intercropping A B ST R A C T Infiltration is a process by which water penetrates through the soil by its surface, and its dynamics can be influenced by several factors, among them, the soil management system adopted. The objective of this work was to estimate water infiltration rate and soil organic matter content in maize and forage intercropping systems. The experiment was conducted in a randomized block design with three replications. Five treatments under no-tillage management were evaluated: 1) Corn (Zea mays L.), 2) brachiaria humidicola (Brachiaria humidicola), 3) Corn and brachiaria humidicola intercropping, 4) Aruana grass (Panicum maximum cv. Aruana), 5) Corn and Aruana grass intercropping. The double ring infiltrometer method was used to determine the basic infiltration rate (VIB). Soil physical properties and soil organic matter were evaluated and correlated with VIB values. Results revealed high VIB values for no-tillage. The highest VIB values were observed in the corn treatment. VIB values decreased with the inclusion of forages. All cultivation systems showed a decrease of organic matter with depth.

SUMMARYPhosphorus fertilization and irrigation increase coffee production, but little is known about the effect of these practices on soil organic matter and soil microbiota in the Cerrado. The objective of this study was to evaluate the microbiological and oxidizable organic carbon fractions of a dystrophic Red Latossol under coffee and split phosphorus (P) applications and different irrigation regimes. The experiment was arranged in a randomized block design in a 3 x 2 factorial design with three split P applications (P1: 300 kg ha -1 P 2 O 5 , recommended for the crop year, of which two thirds were applied in September and the third part in December; P2: 600 kg ha -1 P 2 O 5 , applied at planting and then every two years, and P3: 1,800 kg ha -1 P 2 O 5 , the requirement for six years, applied at once at planting), two irrigation regimes (rainfed and year-round irrigation), with three replications. The layers 0-5 and 5-10 cm were sampled to determine microbial biomass carbon (MBC), basal respiration (BR), enzyme activity of acid phosphatase, the oxidizable organic carbon fractions (F1, F2, F3, and F4), and total organic carbon (TOC). The irrigation regimes increased the levels of MBC, microbial activity and acid phosphatase, TOC and oxidizable fractions of soil organic matter under coffee. In general, the form of dividing P had little influence on the soil microbial properties and OC. Only P3 under irrigation increased the levels of MBC and acid phosphatase activity.Index terms: P cycling, soil microbial activity, acid phosphatase, soil organic matter.( Adriana Rodolfo da Costa et al. RESUMO: ATRIBUTOS MICROBIOLÓGICOS E FRAÇÕES OXIDÁVEIS DO CARBONO ORGÂNICO DE LATOSSOLO CULTIVADO COM CAFEEIRO, SOB PARCELAMENTOS DE FÓSFORO E REGIMES HÍDRICOS

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