O preparo mecânico do solo influencia o seu manejo e danifica a estrutura, diminui a porosidade e a infiltração de água
e aumenta o escoamento superficial. Utilizando-se simulador de chuvas, estudaram-se os tratamentos, preparo convencional
(PC); semeadura direta em resÃduo queimado (SQ); semeadura direta em resÃduo dessecado (SD); e semeadura direta
tradicional em resÃduo dessecado (ST), cultivados, além de um preparo convencional sem cultivo do solo (SC – testemunha)
e de um campo nativo (CN), em um Nitossolo Háplico no Planalto Sul Catarinense, entre março de 2001 e
fevereiro de 2004, com o objetivo de quantificar o escoamento superficial. Ao milho e feijão se aplicaram três testes de
chuva em cada um e à soja cinco testes. Quantificaram-se os tempos de inÃcio (TI) e pico (TP) de enxurrada, a taxa
constante (TE) e o volume de enxurrada (VE) e o coeficiente C da Equação Racional. Os TI, TP e TE, coeficiente C e VE,
foram influenciados pelo preparo e cultivo do solo. O TI e o TP foram menores nos tratamentos PC e SC, enquanto a TE,
o coeficiente C e o VE, também foram menores, mas nos tratamentos SD e ST. A TE variou de 18 mm h-1 na ST a 44 mm h-1
no SC, enquanto o coeficiente C variou de 0,29 na ST a 0,71 no SC. A variação do VE foi de 106 m3 ha-1 na ST a
434 m3 ha-1 no SC, na média dos cultivos.
Soil tillage influences soil management and damages structure, reduces the porosity and water infiltration and increases
surface runoff. A rotating-boom rainfall simulator was used to investigate the treatments: conventional tillage (CT), notillage
in burn residue (NB), no-tillage in desiccated residue (ND), and traditional no-tillage in desiccated residue (NT),
both cropped, as well as conventional tillage without crop (bare soil – BS), and native pasture treatment (NP), in a Typic
Hapludox soil, in the Southern Plateau of Santa Catarina State, Brazil, from March, 2001 to February, 2004, with the
objective of quantifying surface runoff. Three simulated rainfall tests were applied in maize and bean crops and five in
soybean crop. The surface runoff initial time (IT) and surface runoff peak time (PT), the surface runoff constant rate (RR)
and surface runoff volume (RV), and C coefficient of the Rational Equation were quantified. The IT, PT, RR, RV and C
coefficient changed with soil tillage treatments and with soil cultivation. The IT and PT were smaller in the CT and BS
treatments, while the RR, RV and RC were smaller in ND and NT treatments. The RR changed from 18 mm h-1 in NT to
44 mm h-1 in BS treatments, while the RC changed from 0.29 in NT to 0.71 in BS treatments. The VE varied from
106 m3 ha-1 in ND to 434 m3 ha-1 in BS treatments.
