PERDAS DE SOLO E NUTRIENTES POR EROSÃO HÍDRICA EM ...

ABSTRACT
The overall objective of this work was to evaluate different soil tillage systems to planting
Pinus taeda, related to the process of water erosion, in two plantation areas located in the
northern part of Santa Catarina state, on soils of different texture and slopes. Selected areas
were: Tres Barras County – Argissolo Vermelho Escuro Álico (Ultisol) with a heavy clay
texture and slope between 3 and 5%, and in Itaiopolis County Argissolo Vermelho
Distrófico Típico (Ultisol) with a clay texture and slope between 9 and 12%. The soil and
nutrient losses from each soil tillage system were quantified and soil physical, chemical and
mechanical characteristics from both areas were determined. The following soil tillage
systems (treatments) were tested: “Downslope” – ripping and harrowing on the slope
direction; “Contour planting” – ripping and harrowing in contour; “No tillage” – planting
without soil disturbance; and “Planting spot” – mechanical digging on the planting line. The
experimental plots measuring 20 x 25 m were set up in 2003 and monitored over the period
of one year. Soil and water losses were quantified using a Coshocton wheel type device at
the lower end of each plot. Significant differences were found for soil total, macro- and
micro-porosities from both experimental areas. On both places, soil tillage system
“Downslope” presented the largest soil and nutrient losses. On Itaiopolis experimental area,
“Downslope” system presented soil losses 3.5 times bigger than “Contour planting” and “No
tillage” systems, and twice the losses from “Planting spot” system. On this location, no
critical values for soil physical and mechanical characteristics were obtained. On the Tres
Barras experimental area, soil losses from “Downslope” system presented values around 3.5
times greater than those from “Contour planting” system, 2.5 times the losses presented on
“Planting spot” system and almost 6.5 times the losses from “No tillage” system. On this
spot, soil mechanical resistance showed significant differences due to soil compaction
mainly on the reduced tillage systems. In the Itaiopolis area, it was found that soil tillage
must focused on restraining the water erosive process, while on the Tres Barras area, soil
tillage system most important objective should be reclaiming soil structure.
Key words: reforestation, erosion by water, soil physical characteristics
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