on-farm experiments were designed to investigate the response of maize establishment and grain yield to variation in tillage systems. the tillage treatments included arara ploughing followed by zig-zag harrowing and arara ridging (t1); emcot ploughing fol-lowed by zig-zag harrowing and emcot ridging (t2); mouldboard ploughing followed by disc harrowing and mouldboard ridging (t3); disc ploughin...

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...

with respect to the physical and mechanical limited qualities of bitumen, it benefits from certain specificability in application and its life service. polymers as the most important modifiers of bitumen are applied to it in order to improve its functional efficiency. among various polymers, styrene-butadiene- styrene (sbs) is the best modifier of the bitumen. in this work, sbs polymer as one o...

depth of frost penetration is one of the main indices in agriculture, civil and transportation engineering. soil temperature is a function of several factors including: topography, solar radiation, air temperature, moisture content and other physical properties of soil such as thermal capacity, coefficient of heat conductivity, and specific heat. the main objective of the present paper is to de...

soil compaction is an important aspect of agriculture and different methods are available to measure this parameter. one method is called the cone index; measuring the force required per unit area for penetration of a standard steel cone into the ground. cone penetrometers are used for cone index measurement. in this study, a tractor mounted, hydraulically-operated penetrometer was designed, bu...

the liquefaction resistance of soil can be evaluated using laboratory tests such as cyclic simple shear, cyclic triaxial, cyclic torsional shear as well as field methods like standard penetration test (spt), cone penetration test (cpt) and shear wave velocity (vs). in this regard, this study attempts to compare the results of the spt based on the simplified procedure proposed by seed and idriss...