Soil water dynamics related to the degree of compaction of two brazilian oxisols under no-tillage

Edson Campanhola Bortoluzzi,Vanderlei Rodrigues Da Silva,Dalvan José Reinert,José Miguel Reichert

doi:10.1590/s0100-06832009000500003

Edson Campanhola Bortoluzzi, Vanderlei Rodrigues Da Silva + Show 2 more

Open Access

https://doi.org/10.1590/s0100-06832009000500003

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Abstract

Soil water properties are related to crop growth and environmental aspects and are influenced by the degree of soil compaction. The objective of this study was to determine the water infiltration and hydraulic conductivity of saturated soil under field conditions in terms of the compaction degree of two Oxisols under a no-tillage (NT). Two commercial fields were studied in the state of Rio Grande do Sul, Brazil: one a Haplortox after 14 years under NT; the other a Hapludox after seven years under NT. Maps (50 x 30 m) of the levels of mechanical penetration resistance (PR) were drawn based on the kriging method, differentiating three compaction degrees (CD): high, intermediate and low. In each CD area, the infiltration rate (initial and steady-state) and cumulative water infiltration were measured using concentric rings, with six replications, and the saturated hydraulic conductivity (K(θs)) was determined using the Guelph permeameter. Statistical evaluation was performed based on a randomized design, using the least significant difference (LSD) test and regression analysis. The steady-state infiltration rate was not influenced by the compaction degree, with mean values of 3 and 0.39 cm h-1 in the Haplortox and the Hapludox, respectively. In the Haplortox, saturated soil hydraulic conductivity was 26.76 cm h-1 at a low CD and 9.18 cm h-1 at a high CD, whereas in the Hapludox, this value was 5.16 cm h-1 and 1.19 cm h-1 for the low and high CD, respectively. The compaction degree did not affect the initial and steady-state water infiltration rate, nor the cumulative water infiltration for either soil type, although the values were higher for the Haplortox than the Hapludox.

Highlights

Compacted layers are frequently found in soils managed with no-tillage (NT), as a result of the history of heavy machine and implement traffic over the soil (Carter et al, 1999; Silva et al, 2007; Veiga et al, 2007)
Penetration resistance (PR) of the two soils was summarized in table 1
The penetration resistance (PR) values decrease from the first (0–0.10 m) to the second (0.10– 0.20 m) layer

Summary

Introduction

Compacted layers are frequently found in soils managed with no-tillage (NT), as a result of the history of heavy machine and implement traffic over the soil (Carter et al, 1999; Silva et al, 2007; Veiga et al, 2007). Compacted soil layers are identified by determining mechanical penetration resistance (PR) by penetrographs, and by measuring the soil bulk density (Reichert et al, 2007). These values vary due to innumerable factors, such as the crop type, soil clay content, the manner of conducting the experiment and the soil management system, as well as the soil water content (Klein et al, 1998; Reichert et al, 2007). In spite of the wide range of PR values, 2 MPa is seen as the critical value for penetration resistance for soil and crop conditions in general (Tormena et al, 1999)

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