Roni Fernandes Guareschi

Adubação antecipada na cultura da soja com superfosfato triplo e cloreto de potássio revestidos por polímeros

Neste trabalho, objetivou-se comparar epocas e doses de aplicacao do superfosfato triplo (SFT) cloreto de potassio (KCl) com e sem revestimento por polimero no desempenho produtivo da soja em condicoes edafoclimaticas de cerrado. O experimento foi realizado em Rio Verde, GO, em um Latossolo Vermelho distroferrico. Os tratamentos foram dispostos em delineamento de blocos ao acaso, em esquema fatorial 2x2x2+1. O primeiro fator foi constituido pelos fertilizantes SFT e KCl revestidos ou nao por polimeros, o segundo por duas doses de fosforo e potassio (40 + 40 e 80 + 80 kg ha-1 P2O5 e K2O), e o terceiro, por duas epocas de aplicacao dos fertilizantes (15 dias antes da semeadura e na semeadura). Inclui-se ainda, um tratamento testemunha sem adubacao. Foi avaliada a producao de biomassa, a produtividade de graos e componentes de produtividade. Houve resposta a aplicacao da adubacao com P e K na producao de massa fresca e produtividade, sendo a ausencia de adubacao prejudicial ao desenvolvimento da cultura da soja. A aplicacao a lanco de superfosfato triplo e cloreto de potassio, revestidos por polimeros 15 dias antes da semeadura, proporcionou maior producao de massa seca, numero de vagens por planta e produtividade de graos de soja em relacao aos fertilizantes convencionais. Quando aplicados na semeadura, os fertilizantes convencionais e fertilizantes revestidos por polimeros conferiram a mesma producao de massa seca e produtividade de graos de soja.

Carbono, nitrogênio e abundância natural de δ13c e δ15n em uma cronossequência de agricultura sob plantio direto no cerrado goiano

The conversion of native vegetation in agricultural systems can change with over the years of growing levels of C and N as well as the isotopic signal of 13C and 15N of soil. The objective of this study was to evaluate the contents of C and N and the natural abundance of δ13C and δ15N in the soil profile in a chronosequence of no-tillage agriculture (NT) in the Cerrado (tropical savanna) of Goias (GO), Brazil. For this purpose, areas under NT in Montividiu (GO) with the following characteristics were selected: three years under NT (NT3), fifteen years under NT (NT15), and 20 years under NT (NT20). They were compared to areas of native vegetation (CE) and pasture (PA). Soil samples were collected at depths of 0.00-0.05, 0.05-0.10, 0.10-0.20, 0.20-0.30, 0.30-0.40, 0.40-0.50, 0.50-0.60, 0.60-0.80, and 0.80-1.00 m. The soil of the studied area was classified as a Latossolo Vermelho distroferrico (Oxisol). Soil management in NT after 20 years increased the C and N contents in the surface soil layer (0.00-0.05 m) in relation to other areas assessed. In the other depths evaluated, there has been an increase in C and N contents according to the years since adoption of NT (3 to 15 years); however, these areas have not yet been able to recover the contents of these elements in relation to native vegetation (CE). From the δ13C, it can be seen that the origin of soil organic matter (SOM) in the NT areas is related to plants of the C4 photosynthetic pathway. However, it was found that up to 0.30 m depth, the δ13C have been decreasing over the years since adoption of NT. The lowest values of δ15N were found in the areas of CE and PA, and the highest values were found in NT3, while the NT15 and NT20 areas had intermediate values of δ15N compared to the other areas assessed.

PRODUÇÃO DE SILAGEM DE HÍBRIDOS DE MILHO E SORGO SEM NITROGÊNIO DE COBERTURA EM SAFRA DE VERÃO

Obtaining hybrids that have high percentage of grains in total dry mass, more digestible leaves and stems, and high total dry matter yield is the main objective of silage breeding programs. So, the objective of this research was to evaluate the silage production of hybrid maize and sorghum whole plants without nitrogen fertilization, in the summer growing season. The research was conducted in a medium textured Latossol, in Rio Verde, southeast of the Goias State, Brazil. A randomized blocks design with six treatments and four replications was used. The treatments were maize (P-30F90, DKB-177, and AG-7010) and sorghum (Experimental 1, Experimental 2, and Volumax). For maize, six plants per meter were sown at 0.90 m row spacing, while, for sorghum, eight plants per meter were sown at 0.45 m row spacing. The evaluations consisted of shoot biomass, as well as ratio of fresh and dry mass of maize stalks, leaves, and ears, and sorghum panicles, collected at 105 days after emergence (DAE). The Volumax sorghum hybrid presented the highest shoot biomass yield. Maize hybrids presented a higher proportion of ear/shoot biomass than panicle/shoot biomass of sorghum hybrids, confirming the importance of corn use for silage quality. KEY-WORDS: Zea mays ; Sorghum bicolor ; plant characteristics.

ATRIBUTOS QUÍMICOS E FÍSICOS DO SOLO, ESTOQUES DE CARBONO E NITROGÊNIO E FRAÇÕES HÚMICAS EM DIFERENTES FORMAÇÕES VEGETAIS

Cerrado biome is the second largest Brazilian biome, where different phyto-physiognomical features are observed, which may be influenced by soil factors. Thus, this study aimed to evaluate soil physical and fertility properties (particle size analysis, bulk density - BD and total pore volume - TPV), carbon and nitrogen stocks and chemical fractions of soil organic matter (SOM ) in areas of mesophytic forest, Cerrado and Cerrado sensu stricto in the ecological station of Pirapitinga, Minas Gerais state. The soil was classified as Oxisol and soil samples were collected from the layers 0-0.05, 0.5-0.1, 0.1-0.2, and 0.2-0.4 m. The experimental design was completely randomized. Areas of mesophytic forest and cerrado grow in soil with higher clay compared to the Cerrado sensu stricto , indicating that possibly more clayey soils have higher water holding capacity and nutrient supply to attend the demand more appropriately with larger vegetations. The mesophytic forest area by presenting high waste disposal of plant and be in the clayey soil is in some layers providing higher levels of soil organic C and humic substances, triggering lower values ​​of bulk density, greater total porosity and availability of P in relation to other vegetation types studied. However, the closed areas and Cerrado sensu stricto have higher amounts of Mg, K, and lower pH, H + Al and Al compared to mesophitic forest area, which may suggest that these phytophysiognomies settle preferentially in the most fertile soils of Cerrado biome. The relationship between the humic acid and fulvic acid fraction indicates that the forest vegetation Mesophytic presents for vegetation of Cerrado and Cerado sensu stricto soil organic matter of great quality, which allows the establishment of physical and chemical attributes favorable to the development of the plant. The largest stocks of carbon are verified in larger vegetation, cerrado and mesophytic forest. However, the higher grade and stock soil nitrogen occur in Cerrado sensu stricto .

Estoque de Carbono e Nitrogênio e Abundância Natural de δ13C na Estação Ecológica de Pirapitinga, MG

The integrated assessment of physical attributes, carbon (StockC) and nitrogen (StockN) stock, and natural abundance of δ13C are effective in detecting landscape changes. Therefore, this study aimed to evaluate and compare the bulk density, StockC, StockN and natural abundance of δ13C in the soil profiles of different vegetation types of the Pirapitinga Ecological Station (EEP), to elucidate the changes in this area. For this, soil samples were collected and analyzed at depths up to one meter in different vegetation types of the EEP. The highest soil clay content and density of plant of forest vegetation promoted higher levels of StockC and StockN and lower bulk density values than the other grassland vegetation. The δ13C revealed that the areas of forest vegetation types were previously occupied mainly by plants of the C4 photosynthetic cycle, similar to grassland currently found in the EEP.

Carbono, Nitrogênio e Abundância Natural de δ13C do Solo em Coberturas Florestais

The aim of this study was to evaluate and compare the density (Ds) and content of carbon (C) and nitrogen (N), carbon (Cstock) and nitrogen stock (Nstock), and the natural abundance of δ13C in the soil profile of an area of Semideciduous Forest (SF) converted to eucalyptus monoculture (Corymbia citriodora) (ERN) in order to elucidate the changes in these environments. For this purpose, soil samples were collected at depths up to one meter in each study area. The conversion of FES to monocultures reduced Ds, N and EstC in the surface layer. However, there was an increase in EstC in the deeper soil layers. The δ13C isotopic signal of the vegetation that once occupied areas of C. citriodora plantation was similar to that currently found in the area of SF, and the time of conversion was at the depth of 0,40 m in the soil profile.

Organic matter in areas under secondary forests and pasture.

O objetivo deste trabalho foi avaliar a densidade do solo e o estoque de carbono (EstC) do solo, as fracoes quimicas e granulometricas da materia orgânica e o sinal isotopico do DELTA13C do solo em fragmentos florestais e uma area de pastagem mista (MMP). O estudo foi realizado no municipio de Pinheiral, Estado do Rio de Janeiro. As areas avaliadas foram: fragmento de floresta secundaria em estadio inicial (FSEI) com 20 anos de regeneracao; fragmento de floresta secundaria em estadio intermediario (FSEI), com 25 anos de regeneracao; fragmento de floresta secundaria em estadio avancado (FSEA) com 60 anos de regeneracao e uma pastagem mista manejada (PMM). Os atributos relacionados ao carbono do solo mostraram respostas significativas aos efeitos dos processos de degradacao / recuperacao da terra, especialmente para os seguintes indicadores: carbono orgânico total, materia orgânica e materia orgânica particulada. Nao houve alteracoes significativas para as substâncias humicas e foi encontrada a prevalencia da fracao humina. As mudancas mais significativas nos valores de 13C ocorreram ate a profundidade de 60 cm. Na area de pastagem, a 0-10 cm, 67% do estoque de carbono vem de plantas C4, reduzindo nas camadas subsequentes. Nas areas FSEI e FSEA, em 0-10 cm, a contribuicao das plantas C3 foi significativa, com pequenas alteracoes na profundidade.