wind is an important erosive force in deserts, where limited cover of vascular plant material offers little soil-surface protection. erosion and sediment from soil surfaces occurs when wind forces exceed soil threshold friction velocities. soils with physical or biological crusts usually resist wind erosion. this study was conducted by the aim of investigation the effect of trichoderma harzianu...

for a determination of soil characteristics one should have access to instruments that can measure these characteristics, including: soil penetration resistance with high accuracy. one of the accurate instruments commonly employed in soil penetration determinations is cone penetrometer. this apparatus, by measuring soil cone index at different soil depths can provide useful about information ab...

abstract different definitions have been proposed for soil quality. various soil properties have been suggetsted as soil quality indices by researchers. this research was conducted to study the relationship between slope of retention curve at its inflection point (s index) and other soil physical quality indices, because the reserches between s index and soil physical properties are little. thi...

Root caps provide a protective layer in front of the meristem that protects the meristem from abrasion by soil particles. The continuous production and sloughing of the root cap cells may be an adaptation to decrease the friction at the soil-root interface by acting as a low-friction lining to the channel formed by the root. Experiments were performed which provide the first direct evidence tha...

ground skidding on skid trails affects the physical properties of soil. the objective of this study was to evaluate changes in soil physical properties on skid trails formed due to traffic of metal-tracked skidders with regard to soil bulk density, total porosity, water content and penetration resistance. the studies were implemented on two levels of slope – 20% (sc2) – and three levels of traf...

Displacement finite element analysis is performed for a cone-penetration test in cohesionless soils. By modelling finite strain in the soil and large scale sliding at the penetrometer–soil interface, a more realistic penetration process is simulated in which the penetrometer is assumed to be rigid and the soil is assumed to be an elastic-perfect-plastic continuum obeying the Mohr–Coulomb criter...

The root cap assists the passage of the root through soil by means of its slimy mucilage secretion and by the sloughing of its outer cells. The root penetration resistance of decapped primary roots of maize (Zea mays L. cv. Mephisto) was compared with that of intact roots in loose (dry bulk density 1.0 g cm-3; penetration resistance 0.06 MPa) and compact soil (1.4 g cm-3; penetration resistance...

Plant growth is directly affected by soil water, soil aeration, and soil resistance to root penetration. The least limiting water range (LLWR) is de®ned as the range in soil water content within which limitations to plant growth associated with water potential, aeration and soil resistance to root penetration are minimal. The LLWR has not been evaluated in tropical soils. Thus, the objective of...

Excessive harvest of corn (Zea mays L.) stover for ethanol production has raised concerns regarding negative consequences on soil physical quality. Our objective was to quantify the impact of two tillage practices and three levels of corn stover harvest on near-surface soil physical quality through the Least Limiting Water Range (LLWR). We evaluated no harvest, moderate and high stover harvest ...