Structural changes in latosols of the cerrado region: I - relationships between soil physical properties and least limiting water range

Abstract

SUMMARYThe agricultural potential of Latosols of the Brazilian Cerrado region is high, but when intensively cultivated under inappropriate management systems, the porosity can be seriously reduced, leading to rapid soil degradation. Consequently, accelerated erosion and sedimentation of springs and creeks have been observed. Therefore, the objective of this study was to evaluate structural changes of Latosols in Rio Verde, Goiás, based on the Least Limiting Water Range (LLWR), and relationships between LLWR and other physical properties. Soil samples were collected from the B horizons of five oxidic Latosols representing the textural variability of the Latosols of the Cerrado biome. LLWR and other soil physical properties were determined at various soil compaction degrees induced by uniaxial compression. Soil compaction caused effects varying from enhanced plant growth due to higher water retention, to severe restriction of edaphic functions. Also, inverse relationships were observed between clay content and bulk density values (Bd) under different structural conditions. Bd values corresponding to critical soil macroporosity (Bdc MAC ) were more restrictive to a sustainable use of the studied Latosols than the critical Bd corresponding to LLWR (Bdc LLWR ). The high tolerable compression potential of these oxidic Latosols was related to the high aeration porosity associated to the granular structure.Index Terms: soil compaction, degradation of agricultural soils, soil penetration resistance, water availability, soil texture. RESUMO: ALTERAÇÕES ESTRUTURAIS DE LATOSSOLOS REPRE-SENTATIVOS DA REGIÃO DO CERRADO: I -RELAÇÕES EN-TRE PROPRIEDADES FÍSICAS DO SOLO E INTERVALO HÍDRICO ÓTIMO

Interrelationships Among Weed Management in Coffee Plantation and Soil Physical Quality

“…The bulk densities values from soil samples following post-emergence herbicide and mechanical mowing weed management systems at all the depths, and those from the rotary tilling managements (10-13 and 25-28 cm depths), coffee tandem disk harrowing and preemergence herbicide (0-3 and 10-13 cm depths) were considered higher than critical values for clay soils (1.2 Mg m -3 ) in agreement with other studies including Derpsch et al (1991); Dexter (2004); Severiano et al (2011) and critical values for coffee root growth in Dystropherric Red Latosol (Araujo-Junior et al, 2011). The disk harrowing and preemergence herbicide weed management systems promote the crusting in the soil surface (Photos 1B and 1C) and increase the values of the bulk density (Fig.…”

Least limiting water range in assessing compaction in a Brazilian Cerrado latosol growing sugarcane

“…This excess material was used to physically characterize the soil (Table 2) and to determine the permanent wilting point (matric potential of -1.5 MPa) using a Richards extraction chamber (Embrapa, 2011). The undisturbed samples were first saturated and subjected to a matric potential of -0.006 MPa to determine microporosity and field capacity (Severiano et al, 2011;Embrapa, 2011). The samples were then adjusted to water content levels ranging from 0.05 to 0.43 dm 3 dm -3 for the penetration test using a Marconi model MA 933 penetrometer (Piracicaba, SP, Brazil) equipped with an electronic speed control and datarecording system, as described by Tormena et al (1998).…”

Sweet Sorghum Performance Affected by Soil Compaction and Sowing Time as a Second Crop in the Brazilian Cerrado

“…This result indicates that anoxia will occur only when the soil structure is extremely degraded (such as the effects of a high level of compaction) or for relatively short time periods when the soil water content is above field capacity, due to the dynamic behavior of water in the soil (Severiano et al, 2011).…”

“…These samples were saturated by water through gradual addition of distilled water in trays, and subjected to 0.006 MPa matric potential on glass plates in Büchner funnels. The volumetric water content obtained was considered to the soil microporosity and field capacity (Severiano et al, 2011).…”

“…This result indicates that a slight compaction of oxidic Latosols can increase sorghum yield, probably by improving water redistribution in the soil profile compared to soils without machinery traffic (Severiano et al, 2011). This slight compaction can increase contact between soil and roots and increase nutrient-uptake efficiency, compared to excessively loose soils (Håkansson and Voorhees, 1998).…”