field evaluation of a grain drill equipped with jointers for direct planting in previous wheat crop residues

In conventional agriculture, a large amount of energy is consumed in fuel consumption and depreciation of farm tractors and any other farm equipment mostly in tillage and planting operations. the main purpose of this research was to evaluate a tillplanting unit equipped with three jointers. this unit was expected to act as conventional furrow openers such as shovel openers tilling the soil and plant simultaneously, which could reduce farm traffic and farming costs. the unit performance was compared to that of a grain drill. the control experiment was conducted on a moldboard plowed soil, disked by a tandem disk harrow and planted by a pneumatic grain drill. the experimental site was also covered with previous wheat crop residue and the soil was clay with loam at 15.2% d.b. moisture content. the working depth was 6 and 20 cm for direct planting and conventional system, respectively. the experiments were performed at three tractor forward speeds (4, 6 and 8 km h^-1) in triplicate in the experiment site of shiraz university, shiraz, iran. results indicated that the direct planting system reduced the operation time, fuel consumption, draft and specific drawbar energy 65, 60, 75 and 80%, respectively as compared to the conventional practice. however, values of the mean weight diameter and seedling growth rate did not show any significant difference in the two cases at 5% level. furthermore, moisture retention in direct planting system increased 1.87% per 10 days as compared with the conventional farming system.