To understand the mechanisms underlying the compressive behaviour of soil and to estimate [[sigma].sub.p] as a function of readily measurable physical attributes in soils, the impacts of water content and soil bulk density on soil strength, proposing pedo-transfer functions to predict [[sigma].sub.p] were examined in an Ultisol
cultivated with sugarcane.
Here, we measured P and dissolved organic carbon (DOC) sorption isotherms on 23 soils from tropical Oxisol, Ultisol
, Inceptisol, Andisol, and Aridisol soils using P concentrations from 10 to 500 mg P L and DOC concentrations from 10 to 100 mg DOC [L.sup.-1] Isotherms were fit to the Langmuir equation and parameters were related to soil characteristics.
The soil was classified as Argissolo Amarelo (SANTOS et al., 2013), (Ultisol
, according to SOIL SURVEY STAFF (2014)) and presented the following characteristics: pH: 4.64, organic carbon: 11.6g [kg.sup.-1], CEC: 1.88cmol [kg.sup.-1], P: 1.82mg [kg.sup.-1], K: 25.4mg [kg.sup.-1], total Cu: 100mg [kg.sup.-1].
The soil of the experimental area was classified as Red-Yellow Argissolo (EMBRAPA, 2006) (Ultisol
) of medium texture and presented flat relief.
Laboratory batch experiments were carried out to investigate the adsorption and desorption of Zn and Cu in an Oxisol and Ultisol
amended with three rates of sewage sludge (T1=0% (control), T2=5% and T3 =10% sludge).
TABLE 1: Size grain of Ultisol
in the study area in Sao Francisco de Assis, RS state, Brazil.
It belongs to the order ultisol
and classified as typic haplustult.
The soil is sandy loam at 0-20 cm depth and belongs to the order ultisol
, which is classified as typic haplustult .
Correspondence between the Brazilian System of Soil Science (SiBCS) and Soil Taxonomy (US) is an adaptation, because Argissolo, Cambissolo, and Neossolo are considered as Entisol, Inceptisol, and Ultisol
, respectively, but the terms do not have the same meaning exactly.