Abstract
Soil is the basis underlying the food production chain and it is fundamental to improve and conserve its productive capacity. Imbalanced exploitation can degrade agricultural areas physical, chemical and biologically. The objective of this study was to evaluate some soil physical properties and their relation with organic carbon contents of a Humic Dystrudept under conventional tillage (CT) and no-tillage (NT), for 12 years in rotation (r) and succession (s) cropping systems. The experiment was carried out in Lages, SC (latitude 27 º 49 ' S and longitude 50 º 20 ' W, 937 m asl), using crop sequences of bean-fallow-maize-fallow-soybean in conventional tillage rotation; maize-fallow in conventional tillage succession; bean-oat-maize-turnip-soybean-vetch in no-tillage rotation; and maize-vetch in no-tillage succession. The experimental design was completely randomized with four replications. The soil samples were collected in the layers 0-2.5, 2.5-5, 5-10, and 10-20 cm. The following properties were analyzed: soil density, porosity, aggregate stability, degree of flocculation, water retention, infiltration, mechanical strength, and total organic carbon. Soil aggregation in the surface layer (0-5 cm) was better in the no-tillage than the conventional system, related to higher microporosity, organic carbon contents and water retention capacity, indicating that a periodical tillage of this soil is unnecessary. Infiltration was highest in no-tillage with crop succession.
Highlights
Soil is fundamentally important for human survival on earth, representing the most valuable natural resource of agriculture, which depends on conservation or improvement of the productive characteristics
Density was lower in the 0–2.5 cm and 10–20 cm layers of the NTs than the other treatments, but not in the 5–10 cm layer
This behavior accompanied a reduction in soil porosity with increasing depth; a total porosity was greater in the top layer in NTs than the other treatments (Figure 1b)
Summary
Soil is fundamentally important for human survival on earth, representing the most valuable natural resource of agriculture, which depends on conservation or improvement of the productive characteristics. In terms of the physical condition, soil degradation is related to structural modifications that affect water retention capacity, root growth and nutrient availability, reducing crop development and increasing the erosion risk (Bertol et al, 2001) Such modifications are intimately linked to conventional soil preparation, where soils are regularly disturbed, altering soil aggregation, porosity, density, causing accelerated organic matter decomposition, increased soil losses through erosion and, altering the productive capacity (Llanillo et al, 2006). Soil density is affected by management systems which alter the structure and, as a result, pore volume and distribution These alterations affect important physical and hydric properties such as aeration, porosity, plant water availability, and root penetration resistance (Reichert et al, 2003). Together with soil preparation can affect soil structure, altering density and other related physical aspects (Silva et al, 2008)
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