Restoration of degraded lands by adoption of recommended conservation management practices can rehabilitate watersheds and lead to improving soil and water quality. The objective was to evaluate the effects of grass buffers (GBs), biomass crops (BCs), grass waterways (GWWs), agroforestry buffers (ABs), landscape positions, and distance from tree base for AB treatment on soil quality compared with row crop (RC) (corn [Zea mays L.]–soybean [Glycine max (L.) Merr.] rotation) on claypan soils. Soil samples were taken from 10‐cm‐depth increments from the soil surface to 30 cm for GB, BC, GWW, and RC with three replicates. Soil samples were collected from summit, backslope, and footslope landscape positions. Samples were taken at 50‐ and 150‐cm distances from the tree base. β‐Glucosidase, β‐glucosaminidase, dehydrogenase, fluorescein diacetate hydrolase (FDA), soil organic carbon (SOC), total nitrogen (TN), active carbon (AC), and water‐stable aggregates (WSA) were measured. Results showed that β‐glucosidase, β‐glucosaminidase, dehydrogenase, FDA, AC, WSA, and TN values were significantly greater (P < 0.01) for the GB, BC, GWW, and AB treatments than for the RC treatment. The first depth (0–10 cm) revealed the highest values for all soil quality parameters relative to second and third depths. The footslope landscape had the highest parameter values compared with summit and backslope positions. The 50‐cm distance of AB treatment had higher values than the 150‐cm distance for all measured parameters. Results showed that perennial vegetation practices enhanced soil quality by improving soil microbial activity and SOC.
Core Ideas
Permanent vegetative management (trees and grasses) enhanced soil quality.
Perennial practices improved microbial activity and increased soil organic carbon.
Perennial vegetative practices have agricultural and environmental significance.
Establishing perennial practices is an effective approach to enhance soil quality.
Abstract<p>In this research, the geotechnical properties of the soil profile in Hilla city within Babylon Governorate in the middle parts of Iraq are described. The geotechnical data at the specific sites were collected from some geotechnical investigation reports performed at some selected locations. This article is devoted to studying the distribution of soil properties (the physical and mechanical) in the horizontal and vertical directions. Moreover, a correlation between different physical and mechanical properties is performed. The correlation is executed using statistical analysis by Microsoft Excel Software (2016). From the regression results, it was found that the nature of the soil is c</p>
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This paper presents the results of experimental investigations to predict
the bearing capacity of square footing on geogrid-reinforced loose sand by
performing model tests. The effects of several parameters were studied in
order to study the general behavior of improving the soil by using the
geogrid. These parameters include the eccentricity value, depth of first layer
of reinforcement, and vertical spacing of reinforcement layers. The results
of the experimental work indicated that there was an optimum
reinforcement embedment depth at which the bearing capacity was the
highest when single-layer reinforcement was used. The increase of (z/B)
(vertical spacing of reinforcement layer/width of footing) above 1.5 has no
effect on the re
Soil stabilization with stone powder is a good solution for the construction of subgrade for road way and railway lines, especially under the platforms and mostly in transition zones between embankments and rigid structures, where the mechanical properties of supporting soils are very influential. Stone powder often has a unique composition which justifies the need for research to study the feasibility of using this stone powder type for ground improvement applications. This paper presents results from a comprehensive laboratory study carried out to investigate the feasibility of using stone powder for improvement of engineering properties of clays.
The study is devoted to both static and earthquake response analysis of retaining structures acted upon by lateral earth pressure. Two main approaches were implemented in the analysis, namely, the Mononobe-Okabe analytical method and the numerical Finite element procedure as provided in the ready software ABAQUS with explicit dynamic method. A basic case study considered in the present work is the bridge approach retaining walls as a part of AL-Jadiriya bridge intersection to obtain the effects of the backfill and the ground water on the retaining wall response including displacement of the retaining structure in addition to the behavior of the fill material. Parametric studies were carried out to evaluate the effects of several factors
The dynamic response of foundation rest on collapsible soil in dry and soaked states is studied through wide experimental programmed. Gypseous soil from Tikrit governorate area was obtained and subjected to various physical and chemical analysis to determine its properties. Steel rectangular footing (400x200x20) mm is manufactured. The machine is fitted to the footing, then the model machine foundation is placed centrally over the prepared soil layer in steel container (1200x 1000x1000)mm with proper care to maintain the center of gravity of whole system lie in the same vertical line with container.Then, the footing is subjected to vertical harmonic loading using a rotating mass type mechanical oscillator to simulate different dynamic lo
In this paper, a shallow foundation (strip footing), 1 m in width is assumed to be constructed on fully saturated and partially saturated Iraqi soils, and analyzed by finite element method. A procedure is proposed to define the H – modulus function from the soil water characteristic curve which is measured by the filter paper method. Fitting methods are applied through the program (SoilVision). Then, the soil water characteristic curve is converted to relation correlating the void ratio and matric suction. The slope of the latter relation can be used to define the H – modulus function. The finite element programs SIGMA/W and SEEP/W are then used in the analysis. Eight nodded isoparametric quadrilateral elements are used for modeling
Stone columns are widely used globally due to theirversatility and relative wide applicability to treat different soil and foundation situations but much of the research undertaken to date has focused on their use in soft soils. In countries like Iraq the use of stone columns is still limited from a practical point of view, chiefly as many other soil conditions are commonly encountered. These include collapsible soils: soils that are prone to relatively rapid volume compressions (through collapse of metastable fabrics) that occur due to the action of load and/or increases in water content. Recent work has opened up the possibility to use stone columns in these soils by the use of encasement, thereby overcoming the impact of loss of lateral
