R E S U M OA queima da palhada nos canaviais deverá ser suprimida no Brasil e, por conseguinte, aumentar a colheita mecanizada devido às mudanças nos sistemas de produção e exigências ambientais. Neste trabalho são sintetizados estudos sobre o manejo da colheita da cana-de-açúcar (crua e queimada) e modificações em atributos de solos de tabuleiro apontando demandas de pesquisa. Em geral, os estudos investigaram atributos na camada arável do solo, ou seja, pouco se avaliou sobre os efeitos da queima nas camadas mais profundas mesmo diante da ocorrência do caráter coeso em solos de tabuleiro, que impõe diferenças no manejo desses solos. Quanto ao tempo de experimentação os trabalhos, em geral de curta duração, não indicaram diferenças nos atributos do solo com a mudança de sistema de colheita, embora indiquem que esses efeitos podem surgir a médio ou a longo prazo. Os atributos químicos foram os mais estudados, seguidos dos biológicos e físicos cujos dados indicam que a colheita sem queima altera positivamente os atributos edáficos e a qualidade do solo porém predominam estudos com colheita manual e, portanto, insuficientes para suprir informações sobre a colheita mecanizada e sem queima da palhada, nos solos de tabuleiro. Sugarcane harvesting systems: Current knowledge about modifications of attributes in Tableland soils A B S T R A C TThe practice of burning the sugarcane straw in Brazilian plantations has to be eliminated, which will increase the usage of mechanical harvesting, owing to changes in the production systems and the environmental demands. In this paper studies about the influence of cane harvesting management (green and burnt cane) in the attributes of Tableland soils are resumed, also pointing to research demands. In general, the studies investigated the attributes of the arable layer, i.e., little has been studied about effects of the burning practice in the deeper soil layers, even though Tableland soils show a cohesive character that lead to differences in the soil management. About the experiments duration, the usually short term studies did not show differences in the soil attributes due to changes of the sugarcane harvesting system; though they indicated that these effects could happen in medium or long terms. Chemical soil attributes were the most studied followed by biological and physical. The data acquired indicate that harvesting sugarcane without burning alters positively the soil attributes and the soil quality. However, the studies are generally with manual harvesting and, thus, not sufficient to inform about the effect of mechanized harvesting without burning of sugarcane straw in the Tableland soils. Palavras-chave:cana crua e queimada atributos edáficos colheita mecanizada IntroduçãoA degradação das terras agrícolas pela intensificação dos cultivos, sem práticas conservacionistas em sistemas que utilizam monoculturas, desperta a preocupação com a qualidade do solo e a sustentabilidade dos sistemas de produção. Dentre os vários conceitos, Vezzani & Mielniczuc (2009) definem a quali...

RESUMOEstudaram-se os efeitos da adubação nitrogenada sobre o crescimento do capim Tifton 85 (Cynodon spp. cv. Tifton 85), em termos de ocorrência de plantas e altura do dossel, índice de área foliar e interceptação de radiação fotossinteticamente ativa. O estudo foi desenvolvido sobre um planossolo de ocorrência em campo experimental. Os tratamentos consistiram de níveis de N (0; 150; 300; 450 e 600kg/ha de N-ureia, aplicados em duas vezes), arranjados em um desenho experimental de blocos inteiramente ao acaso, com quatro repetições. As avaliações foram realizadas semanalmente, entre 10 e 40 dias após o corte. Tanto a ocorrência de plantas como a altura do dossel responderam à adubação nitrogenada, conforme um padrão de resposta que variou, sazonalmente, em função das doses de N em interação com as condições ambientais. A expansão da área foliar e a interceptação da radiação fotossinteticamente ativa associada, também foram controladas direta e proporcionalmente pelas doses de N aplicadas, sendo maximizadas a valores de índice de área foliar em torno de 4,0.Palavras-chave: Cynodon spp., altura de dossel, frequência de plantas, radiação fotossinteticamente ativa area. Treatments consisted of N levels (0; 150; 300; 450; split ABSTRACT The effects of nitrogen (N) fertilization levels on the growth patterns of the grass Tifton 85 (Cynodon spp. cv.Tifton 85) were studied in terms of occurrence of plants, sward height, leaf area index, and photosynthetically active radiation interception (PAR int ). The field trial was made in an experimental

SUMMARYTo evaluate the impact of trash management on sugarcane production and N fertiliser requirements in environmental conditions of Brazilian coastal tablelands, a simulation was conducted with APSIM-Sugar cropping systems model. The model was parameterised for, and validated against results from a long term (over 23 years) experiment comparing the system-burnt trash and green cane trash blanketing (GCTB), in Linhares-ES. Simulations were conducted over two crop cycles (14 years) with different management (100%, 75%, 50%, 25% GCTB and burnt trash), and N fertiliser rates from 0 to 240 kg ha−1 (in 40 kg ha−1 increments) on the ratoon crops, and 75% of these rates on the plant crops. Measured cane yields and soil carbon were simulated well by the model. The RMSE (root mean square error) of predictions in burnt and GCTB treatments were 14.02 Mg ha−1 and 13.45 Mg ha−1 for yield, and 0.09 and 0.13% for soil carbon. In the simulation, the cane yield responded positively to the GCTB systems. Optimum N rates were higher in the 100%, 75% and 50% GCTB than with burnt trash and 25% GCTB reflecting the greater yields under GCTB systems. The response to trash retention was dependent on N fertiliser, and it was smaller or even negative at lower N rates. With adequate N, the positive responses were predicted to occur in all crops after the imposition of GCTB system. The removal of any proportion of the trash reduced the potential sugarcane yield. The simulations showed that average environmental losses of N are likely to be greater from trash-retained systems at all N fertiliser rates.

There was no effect of increasing N rates on the sugar concentration, although the sugar yield response was positive and strongly influenced by the stalk production. Results showed the importance of reassessing the adequate N rate for maximizing yield in green cane production systems.

The gradual change in management practices in sugarcane (Saccharum spp.) production from burning straw to a green harvesting system, as well as the use of minimum soil tillage during field renovation, may affect soil fertility and soil organic matter (SOM) contents. The objectives of this work were to investigate the influence of sugar cane production systems on: (1) soil fertility parameters; (2) on physical carbon fractions; (3) and on humic substance fractions, in a long-term experiment, comparing two soil tillage and two residue management systems an Xanthic Udult, in the coastal tableland region of Espírito Santo State, Brazil. The treatments consisted of plots (conventional tillage (CT) or minimum tillage (MT)) and subplots (residue burned or unburned at harvesting), with five replicates The highest values of Ca 2+ + Mg 2+ and total organic carbon (TOC) were observed in the MT system in all soil layers, while high values of K + were observed in the 0.1-0.2 m layer. The CT associated with the burned residue management negatively influenced the TOC values, especially in the 0.1-0.2 and 0.2-0.4 m layers. The carbon in the humin fraction and organic matter associated with minerals were significantly different among the tillage systems; the MT showed higher values than the CT. However, there were no significant differences between the sugarcane residue management treatments. Overall, fractioning the SOM allowed for a better understanding of tillage and residue management systems effects on the soil properties. Key words: Saccharum spp. Soil tillage systems. Residue retention. ResumoA mudança gradual nas práticas de manejo da cana de açúcar (Saccharum spp.) de colheita com queima de palha para o sistema de colheita sem queima, bem como o uso de preparo mínimo do solo durante a renovação do canavial, podem afetar a fertilidade do solo e o conteúdo de matéria orgânica do solo (MOS). Os objetivos específicos foram investigar a influência de sistemas de produção de cana-deaçúcar sobre: (1) os parâmetros de fertilidade do solo; (2) sobre as frações físicas do carbono; (3) e em frações de substâncias húmicas, em um experimento de longa duração, comparando dois tipos de preparo do solo e dois sistemas de manejo da palhada em Argissolo Amarelo, na região tabuleiros costeiros do Espírito Santo, Brasil. Os tratamentos consistiram de parcelas (preparo convencional (PC)

Histosols are a natural reservoir of C in the soil, and their drainage followed by other farming practices leads to subsidence and soil organic matter transformations. The objective of this study was to evaluate the influence of use and management of Histosols, by means of: characterizing chemical and physical properties, and the content of SOM and humic fractions; and quantifying C and N stocks. In addition, to obtain preliminary data on greenhouse gas emissions (CO 2 , N 2 O) in Histosol areas with different agricultural practices. Three areas were selected with similar soil and environment, two in Macaé municipality, under pasture, and with bean annual crop rotation, and the third in Santa Cruz, Rio de Janeiro city, cultivated with cassava (Manihot esculenta). The attributes evaluated were: physical-bulk density (BD), particle density (Dp), organic matter density (OMD), mineral matter (MM), mineral residue (MR), aggregate stability; and chemical-pH, exchangeable cations, soil organic matter (SOM), carbon in the humin (HUM-C), humic acid (HAF-C) and fulvic acid (FAF-C) fractions; stocks of C and N; and flux of CO 2 and N 2 O. In general, the area cultivated with cassava had the highest values for exchangeable cations, as a result of fertilizer and soil management practices. The cassava site showed the highest values of BD and Dp; total volume of pores; MM, MR and OMD and higher degree of transformation of SOM; indicating higher alteration of Histosols properties under this usage. In all sites, the C levels indicated dominance of humin fraction. The SOM and C and N stocks were highest in the pasture, indicating preservation of organic matter, with values from 115.92 to 99.35Mg ha-1 of C e 8.35 to 4.45 Mg ha-1 for N. The values of CO 2-C flux were within the range proposed by the IPCC, where the highest emission was 0.09 Mg CO 2 ha-1 day-1 in the pasture site. The values of N 2 ON flux were lower than proposed by the IPCC, with the highest value (270 g N 2 ON m-2 day-1) in the area under beans (crop rotation). In general, the multivariate analyses discriminated the sites and the pasture was the usage that least affected the Histosols properties.

RESUMO -Este trabalho foi realizado com o objetivo de avaliar o consumo, a digestibilidade aparente dos nutrientes e o balanço hídrico em equinos consumindo feno de capim coast-cross em diferentes formas físicas. Foram utilizados quatro equinos mestiços, com idade de 30 meses e peso vivo médio de 200 kg. Os animais foram alimentados com feno de capim coast-cross em quatro formas físicas: inteiro; picado (5 cm); moído a 5 mm; ou moído a 3 mm. O delineamento experimental utilizado foi em quadrado latino 4 × 4, com 10 dias de adaptação às dietas em cada período experimental, 4 dias de coleta de fezes e 1 dia de coleta de urina. A estimativa da digestibilidade aparente dos nutrientes das dietas foi realizada pelo método de coleta total das fezes e a urina foi coletada durante 24 horas utilizando-se coletores de urina. Os coeficientes de digestibilidade aparente e o consumo de nutrientes não diferiram com o processamento do feno, no entanto, o tempo de consumo reduziu com a moagem do feno. Houve maior retenção de água, estimada pelo balanço hídrico, quando fornecido feno picado ou moído a 3 mm. O consumo e a digestão dos nutrientes não são influenciados pelo nível de moagem do feno, porém o balanço hídrico é afetado pelas formas físicas do feno. Não há relação direta entre a redução do tamanho da partícula do feno e o aumento da retenção de água.Palavras-chave: digestão, fibra digestível, tamanho de partícula Intake, apparent nutrient digestibility and water balance in horses fed on different forms of coast-cross hay ABSTRACT -This study was carried out to evaluate intake, apparent nutrient digestibility and water balance in horses fed on different forms of coast-cross hay. Four crossbreed horses, 30 months of age and 200 kg body weight were used. Horses were fed coast-cross hay in four physical forms: long hay; chopped hay (5 cm); ground hay (5 mm) and ground hay (3 mm).The experiment was performed in a 4 × 4 Latin Square design with 15 days for each experimental period (10 days for adaptation to the diets, four days for feces collection and one day for urine collection). Apparent nutrient digestibility was estimated by total feces collection and urinary collection was carried during 24 hours by urine collectors. Apparent digestibility coefficients and nutrient intake did not differ among the diets but the intake time was reduced with hay processing. There was greater water retention, estimated by water balance, when chopped hay or ground hay (3 mm) were fed. Intake and nutrient digestibility were not influenced by levels of hay grinding, but water balance was influenced by the different forms of hay, but a direct relationship was not observed between fiber length reduction and increased water retention.Key Words: digestion, digestible fiber, particle size IntroduçãoCom a expansão da indústria equina, novas formas de processamento das forragens estão sendo adotadas com o objetivo, principalmente, de resolver problemas relacionados ao espaço para armazenamento e ao manuseio trabalhoso, uma vez que as atividades eques...

The recent approach of eliminating the use of fire for sugarcane harvesting (green cane) resulted in managing the crop on a trash-blanketed soil, which changed the content and dynamic of carbon and the nitrogen requirement. These alterations are relevant due to economic and environmental aspects of sugarcane production systems. This study aimed to evaluate changes in total organic carbon (TOC), total nitrogen (TN) and soil organic matter fractions with the application of N-fertilizer on the residues of green cane. The experiment was with sugarcane at the fourth ratoon in Linhares, Espírito Santo State, Brazil. The soil is a Xanthic Dystrudults, originated from Barreiras Group sediments in the coastal tableland region. The treatments were set in a completely randomized blocks experimental