ABSTRACT Decomposition processes and mineralization are essential to determine the time to deploy and manage species in consortia or rotations. The aim of this article was study the dynamics of biomass decomposition and release of macronutrients of plant residues of Fabacea. The species used were: jack bean (Canavalia ensiformis), pigeon pea (Cajanus cajan), dwarf mucuna (Mucuna deeringiana) and sunn hemp (Crotalaria juncea). The experiment was conducted in the field in a randomized block design, 4 x 5 factorial, four species of green manure and five times (0, 30, 60, 90, and 120 days). In the results, sunn hemp and pigeon pea had lower decomposition and release of C, N, K, and Mg. All species, K and P showed similar half-lives (t1/2). For N, sunn hemp presented the lowest coefficient of mineralization (k), 0.0040 g g-1 dia-1, associated with highest t1/2 (173.3 days), already, jack bean showed the highest k (0.0122 g g-1 dia-1) associated with the lowest t1/2 (56.8 days). In edaphoclimatic conditions, use of the jack bean and the dwarf mucuna is recommended for supply of nutrients in shorter periods of time for subsequent crops. However, sunn hemp and pigeon pea are recommended for greater persistence of mulch on the soil.

Abstract The objective of this work was to evaluate the effects of increasing rates of biochar produced with coffee straw, at two pyrolysis temperatures, on the chemical attributes of an Oxisol cultivated with conilon coffee (Coffea canephora) and on the nutrient content of coffee tree leaves. Treatments consisted of pyrolysis at two temperatures (350 and 600 °C) and of five biochar rates (0, 5, 10, 15, and 20 Mg ha-1). The following soil chemical attributes were evaluated: pH in water; P, K, Ca, Mg, Al, H+Al, Zn, Cu, Fe, and Mn contents; effective and potential cation exchange capacity (CEC); sum of bases (SB); base (V) and aluminium (m) saturation; and N, P, K, Ca, Mg, Zn, Cu, Fe, and Mn contents in the leaves. The biochar produced at 600°C, at rates of 10 and 15 Mg ha-1, promoted a greater K release into the soil. Regardless of temperature, coffee straw biochar increased K and P availability, sum of bases, base saturation, and CEC in the soil, but did not influence macro- and micronutrient contents in the leaves. The addition of increasing rates of coffee straw biochar in the soil increases P, K, Mg, SB, CEC, and V, regardless of pyrolysis temperature.

Resumo O objetivo deste trabalho foi avaliar os efeitos de doses crescentes de biocarvão produzido com palhada de café, em duas temperaturas de pirólise, nos atributos químicos de um Latossolo cultivado com cafeeiro conilon (Coffea canephora), e no conteúdo de nutrientes das folhas do cafeeiro. Os tratamentos consistiram de duas temperaturas de pirólise (350 e 600°C) e cinco doses de biocarvão (0, 5, 10, 15 e 20 Mg ha-1). Avaliaram-se os seguintes atributos químicos do solo: pH em água; teores de P, K, Ca, Mg, Al, H+Al, Zn, Cu, Fe e Mn; capacidade de troca catiônica efetiva e potencial (CTC); soma de bases (SB); saturação por bases (V) e por alumínio (m); e teores de N, P, K, Ca, Mg, Zn, Cu, Fe e Mn nas folhas. O biocarvão produzido a 600°C, nas doses de 10 e 15 Mg ha-1, promoveu maior liberação de K ao solo. Independentemente da temperatura, o biocarvão promoveu o aumento de P e K disponíveis, SB, V e CTC no solo, mas não influenciou os conteúdos dos macro e micronutrientes das folhas. A adição de doses crescentes de biocarvão da palha de café conilon no solo promove aumento de P, K, Mg, SB, CTC e V, independentemente da temperatura de pirólise.

ABSTRACT. Soil use and management systems modify phosphorus (P) dynamics by changing the different P compartments. However, the interaction between land-use change and altitude is not clear. This study aimed to evaluate the effect of land use on P forms in different soil aggregate classes of Ultisols located at two altitudes. Soil samples were collected in four land-use systems (agroforestry system, secondary forest, pasture, and eucalyptus) located at two altitudes in the Atlantic Forest biome, Brazil. Phosphorus fractions were assessed using sequential fractionation. In general, recalcitrant forms represented about 70% in the agroforestry system, 66% in the eucalyptus, 65% in the pasture, and 57% in the secondary forest relative to the total P content of all land uses at both altitudes. The soil aggregate classes of smaller diameter presented higher P contents in all fractions. The smallest soil aggregate classes showed up to 65% more P than the classes with smaller diameters in the different land-use systems and altitudes.

ABSTRACT Rational management of spontaneous plants is an alternative for increasing productivity in tree crops. This study aimed to evaluate the impact of management systems between rows and under the canopy of early dwarf cashew trees on the soil chemical properties and light-fraction organic matter and cashew root systems; we also evaluated the nutrient inputs from the spontaneous plants phytomass and cashew leaves deposited on an Arenic Kandiustults. The management systems under study were disc harrowing (DH) and mechanical mowing (MM) between rows, both with clearing under the cashew canopy (crowning), and herbicide (HERB) between the rows and under the canopy (without crowning). Soil and plant samples (leaves, stems, and roots) were collected at three points: under the canopy, at the canopy projected limit, and between the rows of cashew plants, all after seven years of conducting the experiment. Soil samples collected at the layers of 0.00-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.30 m were evaluated for total organic carbon, light-fraction organic matter, and chemical attributes. Dry matter, Na, Ca, Mg, N, P, and K were determined in the spontaneous-plant phytomass from under the canopy, at the canopy projected limit, and between the rows. Results showed that between rows of cashew trees there are higher phytomass input and increases in the light fraction of organic matter, pH and Mg2+ in the soil in the treatment MM. Not removing crop residues or spontaneous plants by crowning promoted accumulation of organic material and higher contents of nutrients under the canopy. The management of spontaneous plants and also soil surface under the canopy of the cashew plants had a great influence on productivity. The crowning, used in MM and DH, led to lower productivity, 1,171.87 and 594.97 kg ha-1, respectively, when compared with the absence of crowning (HERB), which resulted in productivity of 1,363.80 kg ha-1. The practice of crowning is not recommended for soil management systems in dwarf cashew crops.

RESUMO Na última década, o café conilon (Coffea canephora) em consórcio com árvores foi estabelecido para melhorar as condições ambientais. Pouco se sabe sobre como o cultivo de árvores e de banana afetam a qualidade do solo quando consorciados com café conilon. O objetivo do presente estudo foi avaliar os impactos do consórcio de café conilon orgânico com diferentes espécies arbóreas e banana no balanço de C. Cinco sistemas de cultivo, incluindo monocultura de café conilon e consorciados com Inga edulis, Gliricidia sepium, banana BRS Japira (Musa sp.) ou Bactris gasipaes foram estudados em delineamento de blocos ao acaso, com quatro repetições no sul do Espírito Santo, Brasil. Um fragmento de floresta primária adjacente ao experimento foi avaliado para comparação com o consórcio. Amostras superficiais de solo (0 a 10 cm) foram coletadas em 2016 para avaliar o C orgânico total e o N total. A temperatura e umidade do solo de 0 a 5 cm de profundidade e a emissão de CO2 foram medidas mensalmente ao longo de um ano. As espécies plantadas com o café conilon promoveram redução de 5,52% na temperatura do solo e aumento de 17% no teor de umidade do solo. Também promoveu aumento no balanço anual de C, consorciado especialmente com Gliricidia e Inga (4,70 e 3,56 Mg ha-1, respectivamente), com aumento substancial no C orgânico total do solo e N total nos dois sistemas.

ABSTRACT Over the last decade, conilon coffee (Coffea canephora) in consortium with wood trees has been established to improve environmental conditions. Little is known about how individual wood trees and banana affect soil quality when intercropped with conilon coffee. The objective of the present study was to evaluate the impacts of intercropping organic conilon coffee with different wood tree species and banana on C balance. Five cultivation systems including conilon coffee monoculture and intercropped with Inga edulis, Gliricidia sepium, BRS Japira banana (Musa sp.), or Bactris gasipaes were studied in a randomized complete block design, with four replicates at the south of Espírito Santo State, Brazil. A primary forest fragment adjacent to the experiment was also evaluated for comparison with the consortium. Samples of topsoil (0 to 10 cm) were collected in 2016 to evaluate the total organic C and total N. Soil temperature and moisture at 0 to 5 cm depth and the CO2 emission were measured monthly over one year. The species planted with the conilon coffee promoted a 5.52% decrease in the soil temperature and a 17% increase in the soil moisture content. They also promoted an increase in annual C balance, especially intercropped with Gliricidia and Inga (4.70 and 3.56 Mg ha-1, respectively), with a substantial increase in the soil total organic C and total N in both systems.

ABSTRACT The objective of this work was to understand the relationship between decomposition of leaf litter and climatic elements and determine the mineralization of nutrients in the decomposition process in a fragment of Semideciduous Submontane Forest, located in southern state of of Espírito Santo. Overall, 84 litterbags were deposited in 12 permanent plots, collecting one litterbag per plot for 30, 60, 90, 150, 210, 270 and 360 days after the beginning of the experiment. The leaf material remaining in the litterbag was oven-dried and weighed, with later analysis of nutritional compounds. The leaf litter decomposition rate was 1.42, 75.95% of decomposing litter at the end of the evaluation period. Mineralization occurred in the following order: K, Corg., Mg, S, P, N and Ca. There was a positive correlation of average and minimum air temperature, as well as accumulated precipitation and leaf litter decomposition .

Abstract: The objective of this study was to evaluate the organic carbon (OC) distribution and inorganic phosphorus (P) fractions on different soil aggregates classes under forestry fragment of Atlantic Forest, pasture and agroforestry managed for a long period. Soil samples were collected at depths of 0.00-0.10, 0.10-0.20 and 0.20-0.60 m, and the aggregate stability analysis was performed at each depth. The OC and the inorganic P fractions (Pbic readily available, NaHCO3 0.5 mol L-1; PNa1 moderately available, NaOH 0.1 mol L-1; and PNa2 restricted availability, NaOH 0.5 mol L-1) were determined in the respective classes of soil aggregates 4-2, 2-1, 1-0.5, 0.5-0.25 mm. Soil under forestry fragment showed higher OC contents and regardless the land use, highest values of inorganic P were found in the aggregates > 1 mm. Forestry showed highest levels of Pbic, while agroforestry showed the highest levels of PNa1, and pasture had highest values of PNa2.

RESUMO Avaliações visuais dos níveis de degradação das pastagens se difundem pela rapidez, praticidade e baixo custo. No entanto, podem ser subjetivas, interferindo na distinção dos níveis de degradação e na definição de práticas de manejo. Tal fato, associado à falta de padronização do número de níveis e épocas de avaliação, indica a necessidade de mais estudos. Dessa forma, objetivou-se avaliara relação entre níveis de degradação das pastagens separados visualmente e a cobertura do solo mensurada a campo no verão e inverno. Percentagens de capim-braquiária, solo exposto, vegetação espontânea (de folha larga e estreita) e cobertura morta foram avaliadas em 35 áreas com diferentes níveis de degradação visual. A Análise Discriminante Canônica demonstrou que ao diminuir os níveis de degradação visualmente avaliados, obtém-se melhor validação com a cobertura do solo mensurada diretamente a campo no período de verão. A ambiguidade visual entre plantas espontâneas e pastagens nos dois períodos avaliados, assim como do solo exposto e cobertura morta no inverno, dificulta a separação visual dos níveis de degradação. Avaliações visuais da degradação das pastagens devem ser padronizadas no período de verão e simplificadas em dois níveis de degradação, tornando-as mais acuradas e melhor relacionadas com a cobertura vegetal mensurada diretamente a campo.

ABSTRACT Visual assessments of pasture degradation levels are widespread because they are rapid, practical and inexpensive. However, they can be subjective, making it difficult to distinguish between degradation levels to establish management practices. This fact, in association with the lack of standardization of the number of levels and the assessment periods, suggests a need for further studies. The objective of this study was to evaluate the relation between the degradation levels of visually evaluated pastures and the soil cover measured in fields in summer and winter. Percentages of Brachiaria grass, bare soil, spontaneous vegetation (broad and narrow leaf) and mulch were evaluated in 35 areas with different levels of visual degradation. Canonical discriminant analysis showed that a reduction in the visually assessed degradation level correlates better with the field-measured soil cover in summer. Visual distinctions between the degradation levels were difficult by the visual ambiguity between spontaneous vegetation and pasture in both assessment periods and the visual ambiguity between bare soil and mulch in winter. Visual assessments of pasture degradation should be standardized in the summer period and simplified to two degradation levels, making them more accurate and better related to the vegetation cover measured directly on the field.

ABSTRACT Green manures are an alternative for substituting or supplementing mineral nitrogen fertilizers. The aim of this study was to quantify biological N fixation (BNF) and the N contribution derived from BNF (N-BNF) to N levels in leaves of coffee intercropped with legumes grown on four family farms located in the mountainous region of the Atlantic Forest Biome in the state of Minas Gerais, Brazil. The following green manures were evaluated: pinto peanuts (Arachis pintoi), calopo (Calopogonium mucunoides), crotalaria (Crotalaria spectabilis), Brazilian stylo (Stylosanthes guianensis), pigeon pea (Cajanus cajan), lablab beans (Dolichos lablab), and velvet beans (Stizolobium deeringianum), and spontaneous plants. The experimental design was randomized blocks with a 4 × 8 factorial arrangement (four agricultural properties and eight green manures), and four replications. One hundred grams of fresh matter of each green manure plant were dried in an oven to obtain the dry matter. We then performed chemical and biochemical characterizations and determined the levels of 15N and 14N, which were used to quantify BNF through the 15N (δ15N) natural abundance technique. The legumes C. mucunoides, S. guianensis, C. cajan, and D. lablab had the highest rates of BNF, at 46.1, 45.9, 44.4, and 42.9 %, respectively. C. cajan was the legume that contributed the largest amount of N (44.42 kg ha-1) via BNF.C. cajan, C. spectabilis, and C. mucunoides transferred 55.8, 48.8, and 48.1 %, respectively, of the N from biological fixation to the coffee plants. The use of legumes intercropped with coffee plants is important in supplying N, as well as in transferring N derived from BNF to nutrition of the coffee plants.

Resumo O objetivo deste trabalho foi selecionar os indicadores de qualidade de solo mais relacionados à degradação de pastagens, e estabelecer os limites de diferentes níveis de degradação a partir desses indicadores. Cinco pastagens sobre Latossolo Vermelho-Amarelo foram selecionadas, em terço médio da encosta, com diferentes níveis visuais de degradação, tendo-se considerado as variáveis: perda de vigor, presença de espécies espontâneas, solo exposto e erosão. Avaliou-se a cobertura do solo, e coletaram-se amostras nas profundidades de 0,00-0,05, 0,05-0,10 e 0,10-0,20 m, para as análises físicas, químicas e de matéria orgânica. Diferentemente da classificação visual, a análise de agrupamento das variáveis de cobertura indicou apenas dois níveis de degradação: de baixo a moderado e de alto a muito alto, com percentual de classificações corretas acima de 87% na análise discriminante, em que o solo exposto foi a variável mais assertiva para discriminar os níveis de degradação. A matéria orgânica leve e o componente Ca+Mg foram os indicadores de qualidade mais relacionados aos índices de degradação de pastagens à profundidade de 0,00-0,05 m; enquanto o teor de potássio foi o indicador mais relacionado aos índices às profundidades de 0,05-0,10 e 0,10-0,20 m.

Abstract The objective of this work was to select the soil quality indicators more related to pasture degradation and to establish the limits of the different degradation levels using these indicators. Five pasture areas on an Oxisol were selected in the medium third of the slope, with different levels of visual degradation, considering the following variables: loss of vigor, presence of weeds, exposed bare soil, and erosion. Soil cover was evaluated, and soil samples were collected at the 0.00-0.05, 0.05-0.10, and 0.10-0.20-m soil depths, for physical, chemical, and organic matter analyses. Differently from the visual classification, the cluster analysis of the cover variables only indicated two degradation levels: low to moderate and high to very high, with classification percentage above 87% in the discriminant analysis, in which bare soil was the most assertive variable for discriminating the degradation levels. Light organic matter and the Ca+Mg component were the indicators most related to pasture degradation indices at 0.00-0.05 m; while potassium content was the indicator most related to those indices at the 0.05-0.10 and 0.10-0.20-m soil depths.

RESUMOCom o objetivo de comparar três métodos de determinação de carbono orgânico (CO) do solo e de frações das substâncias húmicas, foram avaliadas amostras de dezessete solos do Brasil, de diferentes classes e texturas. Os conteúdos de CO nas amostras foram medidos pelo método da oxidação com dicromato, com e sem aquecimento externo (bloco digestor, 130 oC, 30 min); pelo método de perda por ignição (450 oC/5 h e 600 oC/6 h); e pelo método de combustão a seco. Este último foi usado como referência para medir a eficiência dos demais. Na análise do CO do solo, o método do dicromato com aquecimento externo apresentou maior eficiência e resultados mais próximos do método de referência. No entanto, quando não foi utilizado aquecimento, sua taxa de recuperação caiu para 71%. O conteúdo de CO foi superestimado pelos métodos de perda por ignição. Equações de regressão entre os resultados do método de referência e dos demais mostraram bons ajustes, mas com os interceptos diferentes de zero (p < 0,01), sugerindo que maior exatidão pode ser alcançada considerando toda a equação e não apenas um único fator de correção. Nas substâncias húmicas, o método Walkley-Black subestimou os conteúdos de CO, o que foi associado à oxidação parcial da fração humina. Quando o aquecimento externo foi utilizado, melhores resultados foram obtidos. Nas frações orgânicas, se o método de referencia não está disponível, o CO nos ácidos húmicos e fúlvicos pode ser determinado sem aquecimento externo. Para a fração humina, o aquecimento externo é requerido.

ABSTRACTAiming to compare three different methods for the determination of organic carbon (OC) in the soil and fractions of humic substances, seventeen Brazilian soil samples of different classes and textures were evaluated. Amounts of OC in the soil samples and the humic fractions were measured by the dichromate-oxidation method, with and without external heating in a digestion block at 130 °C for 30 min; by the loss-on-ignition method at 450 °C during 5 h and at 600 °C during 6 h; and by the dry combustion method. Dry combustion was used as reference in order to measure the efficiency of the other methods. Soil OC measured by the dichromate-oxidation method with external heating had the highest efficiency and the best results comparing to the reference method. When external heating was not used, the mean recovery efficiency dropped to 71%. The amount of OC was overestimated by the loss-on-ignition methods. Regression equations obtained between total OC contents of the reference method and those of the other methods showed relatively good adjustment, but all intercepts were different from zero (p < 0.01), which suggests that more accuracy can be obtained using not one single correction factor, but considering also the intercept. The Walkley-Black method underestimated the OC contents of the humic fractions, which was associated with the partial oxidation of the humin fraction. Better results were obtained when external heating was used. For the organic matter fractions, the OC in the humic and fulvic acid fractions can be determined without external heating if the reference method is not available, but the humin fraction requires the external heating.

RESUMO A produção de café conilon em sistemas de manejo orgânico tem aumentado no Estado do Espírito Santo. Porém, faltam informações sobre o impacto desse manejo sobre os estoques de carbono e nitrogênio do solo. Este trabalho teve como objetivo avaliar o efeito da adubação orgânica sobre os estoques de C e N e a densidade do solo (Ds) em agrossistema de café conilon. O experimento foi implantado em lavoura localizada no município de Linhares, ES, no delineamento em blocos casualizados com distribuição fatorial 2 × 2 × 5, com três repetições, sendo os fatores: dois compostos orgânicos; presença e ausência da leguminosa feijão-de-porco nas entrelinhas; e cinco proporções de cada composto em substituição à adubação mineral recomendada (0; 25; 50; 75; e 100 %). Cada repetição foi formada por amostragem de solo sob a copa de uma planta em parcela com 30 cafeeiros. Os compostos foram: composto 1, preparado com capim-elefante e palha de café na proporção 1:1 (v:v); e composto 2, preparado com capim-elefante, palha de café e cama de frango na proporção 2:1:1 (v:v:v). As coletas de solo foram realizadas 240 dias após a adubação (240DAPA) do 1º ano agrícola e aos 30 dias após a 1ª etapa da adubação (30DAPA) do 2º ano agrícola. O uso de composto na adubação do cafeeiro acarretou redução da Ds de aproximadamente 13 %. O incremento das proporções de compostos na adubação aumentou o teor e o estoque de C e N do solo aos 30DAPA do 2º ano agrícola. Houve acréscimos de 11 e 0,4 Mg ha-1 para o estoque de C e N, respectivamente, para cafeeiros adubados com 100 % de composto 1, em relação à adubação mineral. A adubação com composto é alternativa para aumentar os estoques de C e N no agrossistema de conilon.

ABSTRACT Production of Conilon coffee under organic management systems has increased in the State of Espirito Santo, Brazil. However, information is lacking in regard to the impact of these management practices on soil carbon and nitrogen stocks. The aim of this study was to evaluate the effect of organic fertilization on C and N stocks and soil bulk density (Bd) in a Conilon coffee agrosystem. A field experiment was carried out in Linhares, ES, in a randomized block design in a 2 × 2 × 5 factorial arrangement, with three replications. The factors were: two organic composts; presence and absence of the jackbean legume between the rows; and five different proportions of each organic compost (0, 25, 50, 75, and 100 %) to substitute the recommended mineral fertilization. Each replicate consisted of 30 coffee plants. Soil samples were collected under the canopy of each plant. The organic composts were compound 1, prepared from elephant grass and coffee straw in a 1:1 ratio (v:v); and compound 2, prepared from elephant grass, coffee straw, and chicken litter in a 2:1:1 ratio (v:v:v). Soil samples were taken 240 days after fertilization (240DAF) in the 1st crop year and 30 days after the 1st stage of fertilization (30DAF) in the 2ndcrop year. The use of organic compounds to fertilize coffee led to a decrease in Bd of approximately 13 %. The increase in the proportion of organic compounds in fertilization increased the content and stock of C and N in the soil at 30 days after fertilization in the 2nd crop year. There were increases of 11 and 0.4 Mg ha-1 for the stock of C and N, respectively, for coffee plants fertilized with 100 % of compound 1, in relation to mineral fertilization. Fertilization with organic compounds is an alternative for increasing C and N stocks in agrosystems of conilon coffee.

A adubação verde é reconhecida como alternativa viável para melhorar a ciclagem de nutrientes em solos agrícolas. O objetivo deste trabalho foi avaliar a produção de fitomassa e o acúmulo de nutrientes na parte aérea de adubos verdes de verão: feijão-de-porco [Canavalia ensiformis (L.) DC.], guandu-anão (Cajanus cajanvar var. Flavus DC.), mucuna-anã [Mucuna deeringiana (Bort) Merr] e crotalária (Crotalaria juncea L.), sob efeito da adubação nitrogenada e, ou, da inoculação com bactérias fixadoras de N. Utilizou-se o arranjo de parcelas subdivididas, sendo as parcelas constituídas pelas quatro fabáceas e, as subparcelas, por um fatorial 2(2,) cujos fatores e níveis foram: adubação nitrogenada (com e sem) e inoculação com bactérias diazotróficas (com e sem). O delineamento experimental adotado foi o de blocos casualizados, com quatro repetições. Nas condições edafoclimáticas deste ensaio, a crotalária é o adubo verde que apresenta os maiores valores de produção de fitomassa aérea (12,4 Mg ha-1) e acumulação de nutrientes, enquanto a mucuna-anã é a menos eficiente na produção de fitomassa aérea (3,9 Mg ha-1) e acúmulo de nutrientes. Os resultados mostram que não há efeito de adubação nitrogenada, ou de inoculação com bactérias fixadoras de N, na produção de fitomassa aérea ou acúmulo de nutrientes, com exceção da inoculação na ausência de adubação nitrogenada, que resultou (p<0,05) em maior acumulação de P, na crotalária, e maior acumulação de Zn e Mn, na mucuna-anã. Conclui-se que a adubação nitrogenada ou a inoculação com bactérias fixadoras de N2, para o cultivo das fabáceas, são práticas de baixa eficiência nas condições edafoclimáticas estudadas.

Green manuring is recognized as a viable alternative to improve nutrient cycling in soils. The aim of this study was to evaluate the phytomass production and nutrient accumulation in shoots of the summer green manures jack bean [Canavalia ensiformis (L.) DC.], dwarf pigeon pea (Cajanus cajanvar var. Flavus DC.), dwarf mucuna [Mucuna deeringiana (Bort) Merr] and sunn hemp (Crotalaria juncea L.), under nitrogen fertilization and/or inoculation with N-fixing bacteria. A split plot design was arranged with the four Fabaceae species as main plots and nitrogen fertilization (with and without) and inoculation with diazotrophic bacteria (with and without) as the subplots, in a 2² factorial. The experiment was arranged as a randomized complete block design with four replications. In the conditions of this trial, the sunn hemp had the highest production of shoot phytomass (12.4 Mg ha-1) and nutrient accumulation, while the dwarf mucuna had the lowest production of shoot phytomass (3.9 Mg ha-1) and nutrient accumulation. The results showed no effect of nitrogen fertilization or inoculation with N-fixing bacteria on the production of shoot phytomass and nutrient accumulation, except for inoculation without nitrogen fertilization, resulting in greater P accumulation (p <0.05) in the sunn hemp and greater Zn and Mn accumulation in the dwarf mucuna. These findings indicate that N fertilization or inoculation with N2-fixing bacteria for Fabaceae are low efficiency practices in the edaphoclimatic conditions of this study.

O uso de modelos matemáticos pode ser útil para o entendimento das alterações do uso e manejo do solo e fornecem subsídios para testar cenários futuros, possibilitando desenvolver estratégias de manejo menos impactantes ao meio ambiente. Os objetivos deste trabalho foram: (a) usar o modelo Century v4.5 para simular os efeitos dos usos e manejos sobre os estoques de carbono e nitrogênio do solo em diferentes compartimentos, (b) comparar os estoques medidos e simulados pelo Century, e (c) testar impacto de cenários futuros até o ano de 2100. Os tratamentos avaliados foram Pinus, plantio direto e plantio convencional, com histórico das áreas até o momento da coleta de solo (2004). Para o Pinus foram testados três cenários futuros, um deles simulando o mesmo manejo adotado até o momento da coleta de solo, outro reduzindo os eventos de fogo, além do uso sem preparo do solo para o replantio. Para o plantio direto e plantio convencional, simularam-se dois cenários futuros, um com rotação milho/soja e outro com monocultura de milho. O modelo Century foi sensível às mudanças de manejo adotadas, os compartimentos mais lábeis apresentam maior sensibilidade (ativo e lento), do que o mais estável (passivo). Em relação ao estoque de C, o modelo simulou estoques próximos aos medidos no campo, com um erro mínimo de 0,36%. Para os estoques de N, os valores simulados apresentaram erro de 5,71% para os compartimentos mais lábeis. Os cenários futuros mostraram a importância de se evitar queimadas no Pinus e o uso de monocultivo.

The use of mathematical models can be useful for understanding the changes in the use and management of soil and provide aid in testing future scenarios, making it possible to develop management strategies which have less impact on the environment. The objectives of this study were: (a) to apply the Century Model v4.5 in order to simulate the effects of usages and managements on carbon stocks and soil nitrogen in different compartments; (b) compare both the observed stocks and those simulated by the Century Model; (c) to test the impact of future scenarios until the year 2100. The treatments evaluated were of Pine, under both no-tillage and conventional tillage, using historical data from the areas up until when the soil was sampled (2004). For the pine, three future scenarios were tested, one by simulating the management adopted up to the time the soil was sampled, another by reducing the fire events, as well as by soil usage without any preparation when replanting. For both no-tillage and conventional tillage, two future scenarios were simulated: one with corn and soybean rotation, and the other with a monoculture of corn. The Century model was sensitive to the changes in management which were adopted, the more labile compartments showing greater sensitivity (the active and the slow) than the most stable (passive). In relation to stocks of C, the model simulated values close to those measured in the field, with a minimum error of 0.36%. For stocks of N, the simulated values showed an error of 5.71% for the more labile compartments. For pine, the future scenarios demonstrated the importance of preventing fires, and the use of monocultures.

Atualmente, observa-se deterioração da qualidade das águas, a qual está vinculada ao crescimento populacional e as diversas atividades de produção agroindustriais, neste contexto o trabalho teve como objetivo avaliar o desempenho de três espécies forrageiras utilizadas no tratamento de esgoto doméstico (ED) por meio da disposição no solo aplicando a técnica do escoamento superficial. O experimento foi conduzido no Centro de Ciências Agrárias da Universidade Federal do Espírito Santo usando delineamento experimental inteiramente casualizado com três repetições no esquema de parcela sub-subdividida 3x5x2. As parcelas, em três níveis, foram compostas pelas espécies Brachiaria brizantha cv. Marandu, Cynodonsp. cv Tifton 85 e Paspalum atratum cv. Pojuca, nas subparcelas, em 5 níveis as taxas de aplicação de efluentes com 7,91; 15,81; 23,72; 31,63 e 39,54 kg ha-1 dia¹ de DBO e foram realizados dois cortes no material vegetal em ciclos de 28 dias após o início da aplicação dos tratamentos. Os resultados mostraram que o acúmulo de nutrientes pelas forrageiras foi superior aos relatados em literatura para o capim Marandu, Tifton 85 e Pojuca. Esses resultados reforçam o potencial desses capins para o tratamento de águas residuárias, especialmente efluente de ED.

It is evident today that water quality is declining. This deterioration is mainly due to population growth and several aspects of agro-industrial production. This work therefore aimed to evaluate the performance of three forage species which are used for the treatment of domestic sewage (DS) applied to the soil via the superficial runoff technique. This experiment was conducted at the Agrarian Sciences Center of the Federal University of Espírito Santo, Brazil using a completely randomized design experimental delineation, with three replications in a split plot technique 3x5x2. The plots were composed of Brachiaria brizantha cv. Marandu, Cynodon sp. cv Tifton 85 and Paspalum atratum cv. Pojuca, with five levels of effluent application rates in the subplots: 7.91, 15.81, 23.72, 31.63 and 39.54 kg ha-1 day¹ BOD. Two cuts of the plant material were done at 28-day intervals after the treatment application. The results showed that nutrient accumulation by the forage was higher than that reported in literature for Marandu grass, Tifton 85 and Pojuca. These results highlight the potential of these grasses on wastewater treatment, especially DS effluent.