Acúmulo de fitomassa e nutrientes e estádio mais adequado de manejo do feijão-de-porco para fins de adubação verde.

O estudo foi desenvolvido em agroecossistemas manejados sob bases ecológicas no Estado de Mato Grosso do Sul, em Dourados (22º16’ S e 54º49’ W, com altitude média de 408 m, em um Latossolo Vermelho Distroférrico), no ano agrícola 2007/2008 e em Itaquiraí, MS (23º028’ S e 54º011’ W, altitude de 340 m, em um Latossolo Vermelho distrófico típico) em 2008/2009. O objetivo foi avaliar a dinâmica de acúmulo de massa seca e nutrientes na parte aérea do feijão-de-porco e identificar o estádio mais apropriado para o manejo (corte), com vistas a maximizar o aproveitamento do seu potencial para fins de adubação verde. Utilizou-se o delineamento experimental de blocos casualizados, com quatro repetições. Os parâmetros avaliados a cada 15 dias, correspondendo aos 45, 60, 75, 90, 105, 120 e 135 dias após a emergência (DAE), foram: acumulação de massa fresca e seca, N, P, K, Ca, Mg e S, pela parte aérea. Os resultados obtidos mostraram que a leguminosa acumulou elevadas quantidades de fitomassa e nutrientes na parte aérea das plantas e indicam que o estádio mais adequado para o manejo do feijãode- porco para fins de adubação verde corresponde à formação das primeiras vagens e início da formação dos grãos (90 DAE), pois a partir do florescimento continua acumulando expressivas quantidades de massa e nutrientes, principalmente N, K e Ca, maximizando ainda mais seu potencial para promover melhorias nos solos e benefícios às culturas subsequentes

Characterization of biochemical behavior of sorghum (Sorghum bicolor [Moench.]) under saline stress conditions using multivariate analysis

The aim of this research was to characterize the biochemical behavior of sorghum plants under saline stress using multivariate statistical analysis methods for efficient management of Sorghum bicolor [Moench.]). The experimental design was completely randomized design composed of three saline concentrations (0, 1.5 and 2.0 M) in 10 replications. In the multivariate analysis (hierarchical method), there were distinct and sub-groups in the sorghum plant treatments. Group 1 consisted of the root parts and under this group there were two subgroups: 1.5 to 2.0 concentration (Group 1) and 2 concentration (Group 2). The increase of NaCl concentration in the roots and leaves has inverse correlation with decrease of nitrate reductase, amino acids, protein and starch. The amounts of amino acids, carbohydrates, sucrose and proline in the roots and carbohydrates, sucrose and proline in the leaves of sorghum plants are reliable biological indicators of saline stress conditions in the soil. The nitrate compound differed (p ≤ 0.05) in the sorghum plant roots; it had an average value of 0.04 μmol kg-1 of nitrate in the control treatment dry matter. The nitrate average was between 0.04 and 0.06 μmol kg-1, but without statistical difference for all concentrations.Key words: Multivariate statistics, salt concentration, proline, carbohydrate

Emissão de CO2 e sua relação com propriedades, manejo do solo e palha em áreas de cana-de-açúcar

A emissão de CO2 do solo (FCO2) em áreas agrícolas é um processo resultante da interação de diferentes fatores, tais como as condições de clima e solo. Em adição, as práticas adotadas de manejos do solo e da cultura determinam a intensidade desse processo. Neste estudo, objetivou-se: (i) investigar as possíveis relações existentes entre as propriedades edáficas e o processo de emissão de CO2 do solo em áreas sob plantio de cana-de-açúcar, e (ii) o efeito do preparo do solo e da deposição de resíduos da cultura da cana-de-açúcar na FCO2, temperatura e umidade do solo, durante a reforma do canavial. O estudo foi conduzido na área experimental da Embrapa Agropecuária Oeste, em Dourados-MS, e dividido em duas condições de campo. Na primeira condição, foram selecionados 60 pontos ao longo de uma área plantada de 3.000 m2, composta por uma mistura das cultivares (RB 93-5744; RB 72-454; RB 93-5608; RB 85-5113 e SP 83-2847). Para as avaliações da FCO2, foi utilizado o sistema portátil LI-8100, que quantifica a concentração de CO2 em seu interior, por meio de espectroscopia de absorção óptica, na região espectral do infravermelho. Concomitantemente à avaliação da FCO2, foram medidas as variáveis temperatura do solo (termômetro integrante do sistema LI-8100) e umidade do solo (aparelho TDR). A FCO2 apresentou correlações positivas com a matéria orgânica do solo (MOS) (r = 0,67; p < 0,001), a porosidade livre de água (PLA) (r = 0,71; p < 0,001) e o teor de fósforo disponível (r = 0,28; p < 0,05), e negativa com a relação C/N do solo (r = -0,75; p < 0,001) e a umidade do solo (r = -0,29; p < 0,05). Dentre as associações mais expressivas, a FCO2 foi relacionada diretamente com a MOS e a PLA, e inversamente com a relação C/N do solo. Na segunda condição de estudo, após a colheita da...The CO2 emission from soil (FCO2) in agricultural areas is a process resulting from the interaction of different factors, such as climatic conditions and soil. In addition, the adopted practices of soil management and crop determine the intensity of this process. This study aimed to (i) investigate the possible relationships between the soil properties and process CO2 emissions from soil under in areas under cultivation of sugar cane, and (ii) the effect of tillage and crop residue deposition of cane sugar in FCO2, temperature and soil moisture during the reform of the sugar plantation. The study was conducted in the experimental area of Embrapa Agropecuária Oeste, MS, and divided into two field conditions. In the first condition were selected 60 points along a planted area of 3.000 m2 composed of a mixture of cultivars (RB 93-5744; RB 72-454; RB 93-5608; RB 85-5113 and SP 83-2847). For the evaluations of FCO2 was used system LI-8100, quantifying the concentration of CO2 inside by optical absorption spectroscopy in the infrared spectral region. Concurrently with the evaluation of FCO2 were measured soil temperature (thermometer built into the system LI-8100) and soil moisture (TDR device). The FCO2 showed positive correlations with soil organic matter (SOM) (r = 0.67, p < 0.001), free water porosity (PLA) (r = 0.71, p < 0.001) and available phosphorus (r = 0.28, p < 0.05) and negatively correlated with C/N ratio of the soil (r = -0.75, p < 0.001) and soil moisture (r = -0.29, p < 0.05). Among the most significant associations, the FCO2 was directly related to the SOM and PLA, and inversely with C/N ratio of the soil. In the second study condition, after harvesting the sugar cane area was divided into three plots of 25 x 40 m, resulting in the following managements: no tillage and crop residues deposited on the soil surface (SPCR)... (Complete abstract click electronic access below

Efeito do preparo do solo e resíduo da colheita de cana-de-açúcar sobre a emissão de CO2

The soil is one of the main C pools in terrestrial ecosystem, capable of storing significant C amounts. Therefore, understanding the factors that contribute to the loss of CO2 from agricultural soils is critical to determine strategies reducing emissions of this gas and help mitigate the greenhouse effect. The purpose of this study was to investigate the effect of soil tillage and sugarcane trash on CO2 emissions, temperature and soil moisture during sugarcane (re)planting, over a study period of 15 days. The following managements were evaluated: no-tillage with crop residues left on the soil surface (NTR); without tillage and without residue (NTNR) and tillage with no residue (TNR). The average soil CO2 emission (FCO2) was lowest in NTR (2.16 µmol m-2 s-1), compared to the managements NTNR (2.90 µmol m-2 s-1) and TNR (3.22 µmol m-2 s-1), indicating that the higher moisture and lower soil temperature variations observed in NTR were responsible for this decrease. During the study period, the lowest daily average FCO2 was recorded in NTR (1.28 µmol m-2 s-1), and the highest in TNR (6.08 µmol m-2 s-1), after rainfall. A loss of soil CO2 was lowest from the management NTR (367 kg ha-1 of CO2-C) and differing significantly (p<0.05) from the managements NTNR (502 kg ha-1 of CO2-C) and TNR (535 kg ha-1 of CO2-C). Soil moisture was the variable that differed most managements and was positively correlated (r = 0.55, p<0.05) with the temporal variations of CO2 emission from NTR and TNR. In addition, the soil temperature differed (p<0.05) only in management NTR (24 °C) compared to NTNR (26 °C) and TNR (26.5 °C), suggesting that under the conditions of this study, sugarcane trash left on the surface induced an average rise in the of soil temperature of 2 ºC.O solo é um dos principais compartimentos de carbono no ecossistema terrestre, capaz de armazenar quantidades expressivas desse elemento e, portanto, a compreensão dos fatores que contribuem para as perdas de CO2 em solos agrícolas é fundamental para determinar estratégias de redução das emissões desse gás e ajudar a mitigar o efeito estufa. O objetivo deste estudo foi investigar o efeito do preparo do solo e da deposição de resíduos da cultura da cana-de-açúcar na emissão de CO2, temperatura e umidade do solo, durante a reforma do canavial, ao longo de um período de 15 dias. Os manejos avaliados foram: sem preparo do solo e mantendo os resíduos da colheita sobre a superfície do solo (SPCR); sem preparo do solo e sem resíduo (SPSR) e com preparo do solo e sem resíduo (CPSR). A menor média de emissão de CO2 do solo (FCO2) foi observada no manejo SPCR (2,16 µmol m-2 s-1), quando comparado aos manejos SPSR (2,90 µmol m-2 s-1) e CPSR (3,22 µmol m-2 s-1), indicando que as maiores umidades e menores variações da temperatura do solo, observadas em SPCR, foram os fatores responsáveis por tal diminuição. Durante o período de estudo, a menor média diária da FCO2 foi registrada em SPCR (1,28 µmol m-2 s-1) e a maior em CPSR (6,08 µmol m-2 s-1), após a ocorrência de chuvas. A menor perda de C-CO2 do solo foi observada no manejo SPCR (367 kg ha-1 de C-CO2), diferindo significativamente (p<0,05) dos manejos: SPSR (502 kg ha-1 de C-CO2) e CPSR (535 kg ha-1 de C-CO2). A umidade do solo foi a variável que apresentou valores mais diferenciados entre os manejos, sendo positivamente correlacionada (r = 0,55; p<0,05) com as variações temporais da emissão de CO2 nos manejos SPCR e CPSR. Em adição, a temperatura do solo diferiu (p<0,05) somente no manejo SPCR (24 ºC), quando comparada aos manejos SPSR (26 ºC) e CPSR (26,5 ºC), sugerindo que, para as condições deste estudo, o resíduo da cana-de-açúcar retido sobre a superfície propiciou uma temperatura do solo, em média, 2 ºC mais amena

On the spatial and temporal dependence of CO2 emission on soil properties in sugarcane (Saccharum spp.) production

CO2 production in soil is the result of biological processes, such as the decomposition of organic matter and the respiration of roots and soil organisms. It also depends on the physical, chemical and biological properties and their interactions. Such properties exhibit variability in space and time, which provides a high degree of complexity on soil CO2 emission (FCO2). However few studies discuss the spatial and temporal component of FCO2, jointly. The objective of this study was to characterize the spatial and temporal variability of FCO2 and its relationship to the edaphoclimatic properties of the soil in sugarcane fields. The LI-8100 system, which monitors changes in CO2 concentrations within a portable chamber, was used to assess the FCO2. The CO2 flux measurements, soil temperature (0-20 cm, thermometer of LI-8100) and soil water content (0-12 cm, TDR device) were evaluated concomitantly. Overall, the mean values for FCO2, soil temperature and soil water content were 2.8 mu mol m(-2) s(-1), 19.48 degrees C and 17.20 m(3)m(-3), respectively. The FCO2 was positively correlated with the soil organic matter content (SOM) (r = 0.67, p &lt; 0.001), the air-filled porosity (AFP) (r = 0.71, p &lt; 0.001) and the available phosphorus (r = 0.28, p &lt; 0.05) but negatively correlated with the soil C/N ratio (r = 0.75, p &lt; 0.001) and soil water content (r = -0.29, p &lt; 0.05). The air-filled porosity was the last property added to the multiple regression model and explained 77% of the spatial variability in soil CO2 emission. The largest temporal variations in CO2 emissions over the study period were explained by changes in soil water content, especially after rainfall. Spatially, the CO2 emission is modeled by chemical (organic matter and soil C/N ratio) and physical (air-filled porosity) soil properties which are associated to production and transport of CO2 in soil.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Associative diazotrophic bacteria inoculated in sugarcane cultivars: implications on morphophysiological attributes and plant nutrition

Sugarcane is one of the first activities of economic importance in Brazil. The understanding of the nutritional dynamics at different phenological stages of the sugarcane crop with the use of nitrogen-fixing bacteria has been one of the alternatives to decrease fertilizer consumption and increasing plant production. This study aimed to assess the morphophysiological attributes in the initial growth and nutrition of two sugarcane varieties inoculated with strains of diazotrophic bacteria, individually and in an association, in a greenhouse. The experimental design was a randomized block design in a 2 × 8 factorial arrangement with two cultivars (Co 1341-76 and RB 867515) and eight treatments consisting of bacteria inoculated individually with BR 11140T (Azospirillum amazonense), BR 11175T (Herbaspirillum seropedicae), BR 11192T (Herbaspirillum rubrisubalbicans), BR 11281T (Gluconacetobacter diazotrophicus), and BR 11366T (Burkholderia tropica), inoculation associated with the studied bacteria, N fertilization with 120 kg ha-1 of N, and absolute control without inoculation and nitrogen fertilization. Plants were conducted for 75 days after germination, and biometric variables and nutrient accumulation were measured. The sprouting rate index and root fresh matter were significant for inoculation (p<0.01). Inoculation with the strains BR 11192T (H. rubrisubalbicans), BR 11281T (G. diazotrophicus), and RB 11366T (B. tropica) showed the best results for root fresh matter regardless of the cultivar. The strains RB 11366T (B. tropica), BR 11192T (H. rubrisubalbicans), and BR 11175T (H. seropedicae) stood out regarding the sprouting rate index. Inoculation showed a significant effect for stem diameter (p<0.01), especially the strains BR 11140T (A. amazonense) and RB 11366T (B. tropica). All inoculations were efficient for the biometric variable related to leaf length. Nitrogen, Fe, and Zn contents showed a significant effect of the interaction between cultivars and inoculation. The inoculation with the strain RB 11366T (B. tropica), total N fertilization, followed by the other inoculations and the control stood out compared to the cultivar Co 1341-76 within the factor inoculation, indicating that the association of this strain with the cultivar Co 1341-76 is more efficient regarding the recommended commercial N dose for sugarcane. The cultivars Co 1341-76 and RB 867515 responded positively to the individual inoculation of strains of diazotrophic bacteria. The strains promoted improvements in some morphological and/or nutritional attributes of sugarcane plants. The strain B. tropica showed the best interaction with the tested cultivars for the biological N fixation, resulting in gains of biomass productivity and nutrient contents when not inoculated

SPATIAL UNCERTAINTY OF NUTRIENT LOSS BY EROSION IN SUGARCANE HARVESTING SCENARIOS

The assessment of spatial uncertainty in the prediction of nutrient losses by erosion associated with landscape models is an important tool for soil conservation planning. The purpose of this study was to evaluate the spatial and local uncertainty in predicting depletion rates of soil nutrients (P, K, Ca, and Mg) by soil erosion from green and burnt sugarcane harvesting scenarios, using sequential Gaussian simulation (SGS). A regular grid with equidistant intervals of 50 m (626 points) was established in the 200-ha study area, in Tabapuã, São Paulo, Brazil. The rate of soil depletion (SD) was calculated from the relation between the nutrient concentration in the sediments and the chemical properties in the original soil for all grid points. The data were subjected to descriptive statistical and geostatistical analysis. The mean SD rate for all nutrients was higher in the slash-and-burn than the green cane harvest scenario (Student&#8217;s t-test, p<0.05). In both scenarios, nutrient loss followed the order: Ca>Mg>K>P. The SD rate was highest in areas with greater slope. Lower uncertainties were associated to the areas with higher SD and steeper slopes. Spatial uncertainties were highest for areas of transition between concave and convex landforms

Temporal and Spatial Uncertainty of Erosion Soil Loss from an Argisol Under Sugarcane Management Scenarios

ABSTRACT The identification of erosion-susceptible areas is fundamental for the adoption of soil conservation practices. Thus, the best way to estimate the spatial pattern of soil erosion must be identified, in which the process uncertainties are also taken into consideration. The purpose of this study was to evaluate the spatial and temporal uncertainty of soil loss under two scenarios of sugarcane harvest management: green cane (GC) and burnt cane (BC). The study was carried out on a 200-ha area, in Tabapuã, São Paulo State, Brazil. A regular 626-point sampling grid was established in the area, with equidistant intervals of 50 m and a final plant density of about 3.3 samples per ha. The probability that the soil loss would exceed the tolerable limit of 6.67 t ha-1 yr-1 was estimated for each management scenario and after the five harvests. The temporal uncertainty was determined by integrating the estimated annual probabilities, representing the harvests. Areas with soil loss risks above the threshold were identified based on probability maps, generated from the individual and combined dichotomous variables. Soil losses from the BC were highest, during all five harvests. With the exception of the 5th harvest and the entire cultivation cycle under GC, all soil loss estimates were spatially dependent. From the 4th harvest under GC, the probability of the soil loss exceeding the threshold was above 80 % in zero percent of the area, whereas, for BC, the probability exceeded 80 % in 40 % of the area. The production cycle allowed the delimitation of priority areas for the adoption of conservation practices in each management. In the BC, areas with steeper slopes were more likely to exceed the threshold with lower uncertainties