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Engenheiro Beltrão, Brazil

dos Santos W.J.R.,Federal University of Lavras | Curi N.,Federal University of Lavras | Silva S.H.G.,Federal University of Lavras | de Araujo E.F.,CMPC Celulose Do Brazil Ltda | Marques J.J.,Federal University of Lavras
Ciencia e Agrotecnologia | Year: 2013

Water retention in soil is used in many agronomic and environmental applications, but its direct measurement is timeconsuming and expensive. Therefore, pedotransfer functions (PTFs) are alternatives to obtain this information faster and more economically. The objectives of this study were to generate and validate PTFs to estimate the water content at potentials of-33 kPa (field capacity) and-1500 kPa (permanent wilting point) for different soil classes from the central-south portion of Rio Grande do Sul State. The physical and chemical analyses database from soil surveys of the Celulose Riograndense Corp were used. The database is composed of particle size distribution (coarse and fine sand, silt and clay), soil organic matter, and water content data at the above mentioned potentials, besides other information concerning the behavior of the soil classes at field conditions. Firstly, the data were stratified by soil classes and depths, and then 70% of the data were separated for PTF generation and 30% for validation. PTFs were generated for each specific soil class and also general PTFs which were not stratified by soil class, by means of stepwise multiple regression. In most situations, PTFs for a specific soil class showed a better fit than the general PTFs. Proper adjustment of the data showed that the water retention values at potentials of-33 kPa and-1500 kPa can be estimated for the soils from the central-south portion of Rio Grande do Sul State that do not have such analyses through the use of PTFs. Source

Amaral F.H.C.,Federal University of Lavras | Neto A.E.F.,ITV DS Instituto Tecnologico Vale Desenvolvimento Sustentavel | Curi N.,Federal University of Lavras | Inda A.V.,Grande Rio University | Araujo E.F.D.,CMPC Celulose Do Brazil Ltda
Scientia Forestalis/Forest Sciences | Year: 2015

The kinetics of nutrients release can assist in the development of more efficient fertilizer management and rationalization in the use of nutrients in soils cultivated with eucalyptus. The study aimed to evaluate the kinetics of release of potassium (K), calcium (Ca) and magnesium (Mg) in citric acid solution in different concentrations and the relationship between the kinetics of release of these nutrients and the mean annual increment (MAI) of eucalyptus at seven years of age, including soils of the geomorphological provinces of Periphery Depression, Rio Grande Shield and Coastal Plain of Rio Grande do Sul State. The release kinetics were evaluated in citric acid extractor, in equilibrium times which ranged from 2 to 1,808 hours. The most consistent adjustments of release kinetics of K, Ca and Mg were obtained with solutions of citric acid of 0.01 and 0.001 mol L-1, at the depths 0-0,20 and 0,21-0,40 m of all soils. The kinetics of release of K, Ca and Mg varied between soils, the depths and between concentrations of citric acid evaluated, with the highest values of kinetics of release obtained in the Red Argisol and Argiluvic Chernosol that have greater wealth of mineral sources of these nutrients with lower concentrations of citric acid (0.01 and 0.001 mol L-1). The MAI correlated significantly with the kinetics of release K, Ca and Mg, indicating that the kinetics of release comprises an informative parameter of the capacity of these soils to supply nutrients for plants; and should be included in the planning of the fertilization of soils destined for eucalyptus plantations. Source

Oliveira A.H.,Federal University of Lavras | Silva M.L.N.,Federal University of Lavras | Curi N.,Federal University of Lavras | Avanzi J.C.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria | And 2 more authors.
Ciencia e Agrotecnologia | Year: 2013

The constant increasing of eucalyptus forest areas in Brazil requires an accurate monitoring of water erosion. The present study aimed to evaluate soil, nutrients and organic carbon losses occasioned by water erosion in eucalyptus planted forests (EPF) at different development stages (2, 3 and 7 years old). Soil erosion sediments were measured and sampled from standard erosion plots installed on Red Argisol-RA (Ultisol) and Haplic Cambisol-HC (Inceptisol). Soil loss decreased as the age of plants increased; at the beginning of plant development, the canopy barely covered the soil surface, exposing the soil to higher erosion at young EPF plantations. Furrow planting system was used in the Red Argisol area and caused higher soil losses (1.1 to 6.2 Mg ha-1 year-1) as compared to pit planting system that was used in the Cambisol area (1.1 Mg ha-1 year-1). It is known that Cambisol is less resistant to erosion than Argisol. However, using pit system in this EPF, resulted in lower erosion and, therefore, nutrients and carbon losses than the traditional furrow system used in Argisol. Concerning the soil loss, this work points to the need of improving soil conservation practices to prevent soil erosion at the earlier stages of eucalyptus plantation. The amount of calcium and potassium were higher than magnesium in the soil sediment.The relatively high amount of carbon found in the erosion sediments raises additional concerns about the environmental sustainability and deserves future research. Source

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