Improvement of a testing apparatus for dynamometry: procedures for penetrometry and influence of strain rate to quantify the tensile strength of soil aggregates - Figueiredo, Getúlio Coutinho; Silva, Alvaro Pires da; Tormena, Cássio Antonio; Giarola, Neyde Fabíola Balarezo; Moraes, Sérgio Oliveira; Almeida, Brivaldo Gomes de (Revista Brasileira de Ciência do Solo, 2011)