Impacts of land-use changes on soil respiration in the semi-arid region of Brazil
27/Nov/2020
ABSTRACT Soil respiration represents the largest flux of CO2 emission from terrestrial ecosystems, being affected by land-use changes and soil properties. There are few studies investigating the response of soil respiration to land-use changes in the Caatinga biome. This study aimed to measure soil respiration from Caatinga vegetation and degraded pasture, to verify the effect of land-use changes on soil respiration. Measurements of soil respiration were performed using the infrared gas analyzer method over nine months (in rainy and dry […]
Analysis of changes in volume and propagation of cracks in expansive soil due to changes in water content
27/Nov/2020
ABSTRACT Expansive clay soils are a problem for agriculture and engineering because they are susceptible to change in volume due to seasonal variation in water content and temperature. One of its morphological properties is slickensides, which result from the ability to contract and crack when dry and expand by wetting. The objective of this study was to evaluate the processes of expansion and formation and propagation of cracks due to the change in water content over time. The expansion process […]
Winter cover crops effects on soil organic carbon and soil physical quality in a Typical Argiudoll under continuous soybean cropping
27/Nov/2020
ABSTRACT The massive adoption of no-tillage (NT), along with the simplification of the cropping sequences has led to physical and chemical degradation of soils. To recover degraded soils, cover crops have been proposed as an alternative to increase soil organic carbon (SOC) and to improve soil physical quality (SPQ). This study aimed (i) to determine the content of SOC and its physical and chemical fractions at different layers and positions, in a soil with a soybean crop under NT with […]
Comparison of water and osmotic potentials on Vigna unguiculata stress response
11/Nov/2020
ABSTRACT Drought and soil salinity are the main abiotic stresses in semiarid regions of the world. This study aims to evaluate the effect of water tensions generated by the reduction of soil moisture and salt on the leaf water potential of cowpea (Vigna unguiculata L. Walp). The experiments were conducted in a randomized complete block design, with a 6 × 2 factorial arrangement consisted of six soil water tensions (0.025, 0.265, 0.485, 0.705, 0.925, and 1.145 MPa) and two tension […]
Physical properties of a Brazilian sandy loam soil after the traffic of a military vehicle M113 BR
06/Nov/2020
ABSTRACT Soil physical properties can be changed after vehicle traffic, especially by heavy military tracked vehicles. The Santa Maria military Instruction Field, where the experiment was carried out, is currently the most used area for armored tracked vehicles training in Brazil, with the M113 BR being the main equipment. The aim of this study was to determine the effect of the straight line and pivoted traffic intensity of the M113 BR on the physical properties and advancement of the compaction […]
Soil compaction effect on black oat yield in Santa Catarina, Brazil
16/Jul/2020
ABSTRACT Cultivated soils, when submitted to agricultural practices, tend to compact due to the pressure exerted by agricultural machines and implements, a process that compromises soil quality and system sustainability. Specific properties of each soil, such as particle size and organic matter content, interfere with the process and degree of compaction and, consequently, plant growth. This study aimed to analyze the effect of different degrees of compaction (DC) on soil physical properties and black oat (Avena strigosa Schreb) growth. For […]
Glyphosate dynamics prediction in a soil under conventional and no-tillage systems during the crop cycle
05/Jun/2020
ABSTRACT Simulation models are efficient tools to predict the fate of different solutes in agricultural soils. This work aimed to compare measured and predicted glyphosate and AMPA (aminomethyl phosphonic acid; its main metabolite) contents in a soil under no-tillage (NT), and conventional tillage (CT); and to compare the predictions considering constant and time-variable hydraulic properties. Additionally, we evaluated the ability of the model to predict glyphosate and AMPA accumulation during the crop cycle. Hydrus 1-D code was used to predict […]
Structural quality and load-bearing capacity of an Ultisol (Argissolo Vermelho amarelo) in mechanized coffee areas with different deployment times
14/May/2020
ABSTRACT The mechanized management systems used in Brazilian coffee plantations generate heavy machine traffic and lead to the application of loads on the soil that affect the soil structure and lead to widespread compaction. This study aimed to evaluate the influence of mechanized operations on coffee plantations with different deployment times on the soil structural quality of an Ultisol, based on its soil physical properties and soil load-bearing capacity. The experiment was carried out in Muzambinho, São Paulo State, Southeast […]
Using root water uptake estimated by a hydrological model to evaluate the least limiting water range
14/May/2020
ABSTRACT The least limiting water range (LLWR) has been extensively determined, but evaluating if LLWR can indeed indicate soil physical stress on plant growth is still a controversial issue. In this study, we used the Hydrus-1D hydrological model to simulate root water uptake (RWU) to analyze if RWU and LLWR are correlated under stress conditions. The LLWR was determined in a sandy-loam Ultisol and a clayey Oxisol. In both soils, RWU extracted by plants (leaf area index set as 3) […]
Hydrostatic Equilibrium between Soil Samples and Pressure Plates Used in Soil Water Retention Determination: Consequences of a Questionable Assumption
23/Jul/2019
ABSTRACT Soil water retention is among the soil hydraulic properties most routinely measured in studies of soil physics and related areas. This property is used in dynamic simulations of vadose zone processes such as soil water availability, surface boundary processes of evaporation and infiltration, and the fate of soil pollutants. The most common measurement technique consists in establishing a hydrostatic equilibrium between an initially saturated soil sample and a porous medium at a certain tension on a tension table or […]