Evaluation of Energy Requirements and of Crop Residues Burial Efficiency of three Primary Tillage Methods in a Heavy Clay Soil Roberto Fanigliulo, Marcello Biocca*, Marco Fedrizzi, Mauro Pagano, Daniele Pochi CRA – ING Agricultural Research Council, Agricultural Engineering Research Unit Via della Pascolare, 16 – 00016 Monterotondo (Rome) Italy *Corresponding author. E-mail: marcello.biocca@entecra.it Abstract Traditional soil tillage based on medium depth ploughing can determine excessive energy costs, loss of nutrients, decrease of natural fertility and, in some cases, increase of soil erosion caused by wind and water. These negative effects can be reduced by introducing soil tillage methods, such as tilling without inversion of layers and minimum tillage, which aim at maintaining a permanent soil cover and at reducing number and depth of interventions. There are many types of equipment on the market with large work front, formed by assembling various implements in order to fulfill different agronomic functions. The effectiveness of such equipments essentially depends on the texture of the soil and on the amounts of surface weed biomass or crop residues. These can lead to ground accumulation between the tools, especially on heavy clay soil, to reduced working speed and to decreased uniformity of residue mixing and burial across the whole working width. The Agricultural Machinery Testing Centre of CRA-ING (CPMA), accredited as Testing Laboratory (ACCREDIA no. 1141) in accordance with the requirements of the EN ISO/IEC 17025:2005 standard, performed tests to evaluate the operative performances of an innovative combined cultivator, allowing the contemporary execution of deep tillage and soil refining, in comparison with a three furrows, reversible mouldboard plough, for traditional soil primary tillage, and an offset disk harrow, for minimum tillage of untilled soil. The tests were carried out on a flat, silt-clay untilled soil, using a 205 kW instrumented tractor. The objective of this study was to evaluate the energy parameters of each tractor-machine coupling and the quality of their work, especially with reference to the capability of burying biomass residues as a function of working depth and speed. The tests results show a decrease of power and energy requirements proceeding from traditional (thesis A) to more conservative tillage methods (thesis C), that can be synthesized by savings up to 37.6% for the fuel consumption per hour and up to 83.6% for the fuel consumption for surface unit. Intermediate values have been obtained for the combined machine (thesis B). The best performances on biomass burying were provided by the plough and the cultivator. Key words: quality management system, performances, reversible plough, combined cultivator, disk harrow 1. Introduction Traditional soil tillage based on medium depth ploughing and on burning or mulching of residues from previous crops, can determine, as pointed out by numerous experiments in the field of agricultural mechanization (Perfect et al., 1997; Chen et al., 2004), excessive energy costs, loss of nutrients, decrease of natural fertility and, in some cases, increase of soil erosion caused by wind and water. These negative effects can be reduced by introducing soil tillage methods, such as tilling without inversion of layers and minimum tillage, which aim at maintaining a permanent soil cover and at reducing number and depth of interventions. These methods, through crop rotation and maintenance of permanent soil cover of at least 30% of the surface, also aim at reducing the erosion and compaction of soil surface and at preserving its natural fertility, ensuring at the same time, a satisfactory level of production and reduced energy costs (Hanna et al., 1995; Wagner & Nelson, 1995; Raper, 2002;). The soil tillage without inversion of the layers is often adopted in place of deep ploughing. It allows to prepare the soil for superficial refining operations mostly by means of passive