World Applied Sciences Journal 14 (10): 1555-1558, 2011 ISSN 1818-4952 © IDOSI Publications, 2011 Corresponding Author: Dr. Majid Rashidi, Ph.D., Department of Mechanical Engineering, East Tehran Branch, Islamic Azad University, Tehran, Iran. 1555 Effect of Different Tillage Methods on Some Physical and Mechanical Properties of Soil in the Arid Lands of Iran Majid Rashidi and Fereydoun Keshavarzpour Department of Mechanical Engineering, East Tehran Branch, Islamic Azad University, Tehran, Iran Abstract: Field experiments were conducted to investigate the effect of different tillage methods on some physical and mechanical properties of soil, i.e. moisture content (MC), bulk density (BD) and penetration resistance (PR). Tillage treatments in the study were moldboard plow followed by two passes of disk harrow (MDD) as conventional tillage, two passes of disk harrow (DD) as reduced tillage, one pass of disk harrow (D) as minimum tillage and no-tillage (NT). The statistical results of the study indicated that tillage method significantly (P 0.05) affected physical and mechanical properties of soil. The highest MC (20.6%) and the lowest BD (1.34 g cm ) and PR (487 kPa) was observed in case of MDD treatment; while the lowest MC (17.6%) 3 and the highest BD (1.44 g cm ) and PR (1087 kPa) was noted in case of NT treatment. Therefore, conventional 3 tillage method was found to be more appropriate and profitable tillage method in enhancing selected physical and mechanical properties of soil in the arid lands of Iran. Key words: Soil Tillage Moisture content Bulk density Penetration resistance Arid lands Iran INTRODUCTION runoff and crop performance [6]. Conversely, Soil tillage is among the important factors affecting decreased pore space [7], increased soil mechanical soil physical and mechanical properties [1]. Tillage strength [8] and stable aggregates [9]. Whereas, method affects the sustainable use of soil resources conventional tillage decreases soil mechanical strength through its influence on soil properties [2]. The proper and soil bulk density [10]. It also improves porosity and use of tillage can improve soil related constrains, while water holding capacity of the soil. This all leads to a improper tillage may cause a range of undesirable favorable environment for crop growth and nutrient processes, e.g. destruction of soil structure, accelerated use [6]. erosion and depletion of organic matter and fertility [3]. Currently, different tillage methods are being used in Use of excessive and unnecessary tillage operations is Iran without evaluating their effects on physical and often harmful to soil. Therefore, currently there is a mechanical properties of soil. Thus, this study was significance interest and emphasis on the shift to the conducted to determine the effect of different tillage conservation and no-tillage methods [4]. methods on some selected physical and mechanical Conventional tillage practices modify soil structure properties of soil (moisture content, bulk density and by changing its physical and mechanical properties such penetration resistance) in the arid lands of Iran. as moisture content, bulk density and penetration resistance. Annual disturbance and pulverizing caused by MATERIALS AND METHODS conventional tillage produces a finer and loose soil structure as compared to conservation and no-tillage Research Site: This study was carried out at the methods which leave the soil intact [5]. This difference Agricultural Research Site, Garmsar, Iran on a clay loam results in a change of number, shape, continuity and size soil for two successive growing seasons (2009 and 2010). distribution of the pores network, which controls the The research site is located at latitude: 35° 13' N, ability of soil to store and transmit air, water and longitude: 52° 19' E and altitude: 873 m in arid climate agricultural chemicals. This in turn controls erosion, (136 mm rainfall annually) in the center of Iran. conservation tillage methods often result in