Manure application supplies plant nutrients, but also leads to trace element accumulation in soil. This study investigated total and EDTA-extractable B, Cd, Co, Cu and Zn in soil after 25 annual manure applications. The residual effect of 14 annual manure applications followed by 11 yr with no applications was also investigated. Manure was applied at 0, 30, 60 and 90 Mg ha(-1) yr(-1) (wet weight) under rainfed (treatments Mr0, Mr30, Mr60, and Mr90) and at 0, 60, 120 and 180 Mg ha(-1) yr(-1) under irrigated conditions (Mi0, Mi60, Mi120, and Mi180). The manure applications had no significant effect on soil B, Cd and Co content under both rainfed and irrigated conditions, but significantly increased total Cu and Zn content under irrigated conditions with Zn in Mi120 and Mi180 reaching the lower maximum concentration (MAC) level set by the European Community. Manure application also significantly increased EDTA-extractable Cd and Zn content in soil. Up to 27% of the total Cd (0.156 mg kg(-1)) and 21% of total Zn (38 mg kg(-1)) are found in EDTA-extractable form (Mi180 at 0-15 cm). EDTA-extractable Cd and Zn content was also significantly elevated in the irrigated residual plots due to the higher manure rates used. Thus, the impacts of cattle manure application on trace elements in soil are long lasting. Elevated Cd and Zn are a concern as other studies have linked them with certain types of cancers and human illnesses.

The use of dried distillers' grains with solubles (DDGS) in feedlot cattle (Bos taurus) diets is increasing as the bio-ethanol industry expands. This study investigated how wheat (Triticum aestivum L.) DDGS-based diets impact feedlot cattle nutrient and volatile fatty acid (VFA) excretion. Feedlot heifers were fed DDGS at 0 (Control) 20, 40, 60% or 60% + Ca (1% limestone) of dietary dry matter. Feces and manure were sampled monthly over a 133-d finishing period. Total nitrogen (TN) (feces only), total phosphorus (TP), pH (manure only), and water soluble NH(4)(+) and P contents in feces and manure were higher with 40 and 60% DDGS diets than with the Control. Significant increases in isobutyric, valeric, and isovaleric VFAs (by far the most odorous in manure) were also observed in the feces with 40 and 60% DDGS diets, although there was no change in the total VFA content with diet. Wheat DDGS manure, with higher N and P contents, should be beneficial to crop production. However, it could potentially increase N and P loading on crop lands after application and contribute to greater NH(3) emission and malodor intensity while manure is in the feedlot pen. Estimated manure N loss while in feedlot pens also increased significantly with dietary DDGS levels. The small (nonsignificant) differences in total and soluble N and P in feces and manure between 20% DDGS and the Control (0% wheat DDGS) suggest that excess nutrient flow to the environment and malodors can be controlled by restricting wheat DDGS to a maximum of 20% in cattle diets.

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RESUMOForam estudados os efeitos do cultivo contínuo da cana-de-açúcar por meio da análise micromorfológica de Latossolos Amarelos argilosos da região dos tabuleiros costeiros do estado de Alagoas, Brasil. Quatro talhões foram selecionados na Usina Caeté, município de São Miguel dos Campos, AL, em janeiro de 1995, sendo um com vegetação nativa (Tn), e os demais cultivados por períodos de dois (T2), dezoito (T18) e vinte e cinco (T25) anos. Os solos foram morfologicamente caracterizados, sendo coletadas amostras indeformadas dos horizontes A, AB e BA de cada perfil, em caixas de Kubiena, para análises micromorfológicas. Foram coletadas amostras para análises de densidade do solo, macroposidade, carbono orgânico e condutividade hidráulica saturada. Os resultados evidenciam que o uso agrícola dos solos causou mudanças na morfologia do horizonte superficial, com o desenvolvimento de um horizonte Ap, com sensível perda de estrutura. Após um evidente impacto negativo nas propriedades físicas com o primeiro plantio da cana-de-açúcar, o manejo adotado promoveu uma recuperação parcial da macroporosidade no horizonte superficial após 18 e 25 anos de cultivo. Além da formação inicial de uma camada compactada nos horizontes Ap e AB, foi observado um adensamento pedogenético natural do solo no BA, acelerado com o cultivo da cana-de-açúcar, pelo preenchimento de poros com argila iluvial. A porosidade total obtida pelo analisador de imagem nas fotografias das lâminas delgadas corrobora uma sensível redução da porosidade no horizonte superficial com a introdução do cultivo. Mostra também que a porosidade do horizonte BA é baixa no perfil com vegetação nativa, comprovando o caráter pedogenético do adensamento desse horizonte. Apesar de não ter sido observado nenhum revestimento nas unidades estruturais em campo, a micromorfologia mostrou pedofeições morfológicas com revestimentos argilosos nos agregados e enchimento de poros com argila iluvial, o que indica a tendência à formação de horizonte B textural com o tempo.Termos de indexação: Latossolo Amarelo argiloso, propriedades físicas, tempo de cultivo, adensamento, coesão, compactação.

Abstract--Palygorskite and sepiolite show a high sorption capacity for organic molecules. Adsorption of 2 organic cations, methylene blue (MB) and crystal violet (CV), by palygorskite and sepiolite were examined. The maximum sorption of MB and CV far exceeded the cation exchange capacity (CEC) of these minerals. This shows that, besides the contribution of free negative sorption sites (P), the sites satisfied with sorption of single cations (PXi ~ and neutral sorption sites (N) on clay surfaces may contribute to the sorption of organic cations. The number of neutral sites was determined by examining the sorption of 2 neutral organic molecules, triton-X 100 (TXI00) and 15 crown ether 5 (15C5), and by application of the Langmuir isotherm.To determine the contribution of different sites, an adsorption model that applies the Gouy-Chapman equation and takes into account the formation of different clay-organic complexes in a closed system was employed. Application of this model to sorption data provided the calculation of binding coefficients for neutral sites, as well as the surface potential of the minerals at different sorbate concentrations.At sorption maxima, for both palygorskite and sepiolite, the contribution of neutral sites for sorption of organic cations was the highest, followed by the PXi ~ sites in case of CV sorption, while in sorption of MB the contribution of P-sites was the second highest. The Fourier transform infrared (FTIR) patterns of clay-organic cation complexes compared with pure clays confirm that the sorption of organic cations is by silanol groups located at the edge of fibrous crystals, which account for neutral sorption sites.