Performance Of A Reciprocal Shaker In Mechanical Dispersion Of Soil Samples For Particle-size Analysis [avaliação Do Desempenho De Mesa Agitadora Reciprocante Na Dispersão De Amostras De Solo Para Fins De Análise Granulométrica]

The dispersion of the samples in soil particle-size analysis is a fundamental step, which is commonly achieved with a combination of chemical agents and mechanical agitation. The purpose of this study was to evaluate the efficiency of a low-speed reciprocal shaker for the mechanical dispersion of soil samples of different textural classes. The particle size of 61 soil samples was analyzed in four replications, using the pipette method to determine the clay fraction and sieving to determine coarse, fine and total sand fractions. The silt content was obtained by difference. To evaluate the performance, the results of the reciprocal shaker (RSh) were compared with data of the same soil samples available in reports of the Proficiency testing for Soil Analysis Laboratories of the Agronomic Institute of Campinas (Prolab/IAC). The accuracy was analyzed based on the maximum and minimum values defining the confidence intervals for the particle-size fractions of each soil sample. Graphical indicators were also used for data comparison, based on dispersion and linear adjustment. The descriptive statistics indicated predominantly low variability in more than 90 % of the results for sand, mediumtextured and clay samples, and for 68 % of the results for heavy clay samples, indicating satisfactory repeatability of measurements with the RSh. Medium variability was frequently associated with silt, followed by the fine sand fraction. The sensitivity analyses indicated an accuracy of 100 % for the three main separates(total sand, silt and clay), in all 52 samples of the textural classes heavy clay, clay and medium. For the nine sand soil samples, the average accuracy was 85.2 %; highest deviations were observed for the silt fraction. In relation to the linear adjustments, the correlation coefficients of 0.93 (silt) or > 0.93 (total sand and clay), as well as the differences between the angular coefficients and the unit < 0.16, indicated a high correlation between the reference data (Prolab/IAC) and results obtained with the RSh. In conclusion, the mechanical dispersion by the reciprocal shaker of soil samples of different textural classes was satisfactory. The results allowed recommending the use of the equipment at low agitation for particle size- analysis. The advantages of this Brazilian apparatus are its low cost, the possibility to simultaneously analyze a great number of samples using ordinary, easily replaceable glass or plastic bottles.36411311148Baver, L.D., Gardner, W.H., Gardner, W.R., (1972) Soil Physics, pp. 1-53. , New York, John Wiley & SonsCamargo, O.A., Moniz, A.C., Jorge, J.A., Valadares, J.M.A.S., (1986) Métodos De Análise Química, Mineralógica E Física De Solos Do Instituto Agronômico De Campinas, p. 57. , Campinas, Instituto Agronômico de Campinas, Boletim Técnico, 106Day, P.R., Particle fractionation and particle-size analysis (1965) Methods of Soil Analysis, 1 PART, pp. 545-567. , BLACK, C.A. ed, Madison, ASA/ SSSA, Agronomy Monograph, 9(2006) Sistema Brasileiro De Classificação De Solos, p. 306. , EMPRESA BRASILEIRA DE PESQUISA AGROPECUÁRIA - EMBRAPA., 2.ed. Rio de Janeiro, EMBRAPA SOLOS(1997) Manual De Métodos De Análise De Solo, pp. 27-34. , EMPRESA BRASILEIRA DE PESQUISA AGROPECUÁRIA - EMBRAPA, 2.ed. Rio de Janeiro, Centro Nacional de Pesquisa de SolosFletcher, G.J.O., Danilovics, P., Fernandez, G., Peterson, D., Reeder, G.D., Attributional complexity: An individual diûerences measure (1986) J. Personal. Soc. Psychol, 51, pp. 875-884Gee, G.W., Or, D., Particle Size Analysis (2002) Methods of Soil Analysis. Physical Methods, pp. 255-293. , DANE, J.H. & TOPP, G.C., Part 4Grohmann, F., van Raij, B., Dispersão mecânica e prétratamento para análise granulométrica de Latossolos argilosos (1977) R. Bras. Ci. Solo, 1, pp. 52-53Quaggio, J.A., Cantarella, H., van Raij, B., Evolution of the analytical quality of soil testing laboratories integrated in a sample exchange program (1994) Commun. Soil Sci. Plant Anal, 25, pp. 1007-1014Hillel, D., (1982) Introduction to Soil Physics, pp. 21-39. , San Diego, Academic PressNeto, E.L., De, S., Figueiredo, L.H.A., Beutler, A.N., Dispersão da fração argila de um Latossolo sob diferentes sistemas de uso e dispersantes (2009) R. Bras. Ci. Solo, 33, pp. 723-728Ruiz, H.A., Incremento da exatidão da análise granulométrica do solo por meio da coleta da suspensão (silte + argila) (2005) R. Bras. Ci. Solo, 29, pp. 297-300Silva, A.P., Tormena, C.A., Fidalski, J., Imhoff, S., Funções de pedotransferência para as curvas de retenção de água e de resistência do solo à penetração (2008) R. Bras. Ci. Solo, 32, pp. 1-10Tomasella, J., Hodnett, M.G., Rossato, L., Pedotransfer functions for the estimation of soil water retention in Brazilian soils (2000) Soil Sci. Soc. Am. J, 64, pp. 327-338Warrick, A.W., Nielsen, D.R., Spatial variability of soil physical properties in the field (1980) Applications of Soil Physics, p. 385. , HILLEL, D., ed, New York, Academia Pres