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The performance of the movable boards ditch opener (MB) and the conventional ditch opener (CD) was compared using the disturbed area as a comparison parameter to determine the best among the two implements. The experimental factors were three operating depths (30, 40 and 50cm) for MB in the cultivated and uncultivated soils, while for CD in the cultivated soil only, because it could not penetrate the uncultivated soil more than (25cm), three angles between the boards of MB (45, 60 and 750) and one angle between the boards of CD (650) (the angle between the boards of CD was constant because its boards were welded together), three wings widths of the foot of MB (25, 35 and 45cm) whereas, one share width (35cm) for CD (for MB the wings can be changed by another wings of wider width whereas for CD it was provided with share permanently fixed at the lower end of the boards) and two soil conditions (cultivated and uncultivated soils). The results showed that DA (the disturbed area, the cross-section area of the soil manipulated by the implements) for CD and MB increased with operating depth and it was higher in the cultivated soil compared with that in the uncultivated soil for MB only. DA increased with increasing the angle between the boards of MB whereas, for CD the angle was constant so that DA was constant. DA also increased with wings width of the foot of MB while, for CD the width was constant also, so that the DA was constant. The operating depth increased DA more than the angle between the boards, the width of the wings of the foot and the soil conditions. Whereas the angle between the boards surpassed the width of the foot and soil conditions in giving higher DA. However, the width of the wings surpassed the soil conditions in giving higher DA. This means MB gave higher performance than CD in both soil conditions. It also penetrated the uncultivated soil down to 50cm despite of its great resistance whereas, CD could not penetrate this soil type more than 25cm. Thus the field performance of MB was better than CD. In additional to that, it gave wider cross-section width ditches and deeper ditch in both soil conditions compared with CD. Abbreviation: MB=Movable boards ditch opener; CD= Conventional ditch opener; DA= Cross-section area

The field performance of movable boards ditch opener (MB) and conventional ditch opener (CD) was contrasted by using a specific resistance to determine the optimum performance of either one of them. The comparison was conducted using three operating depths (30, 40 and 50cm), three angles between the boards of MB (45, 60 and 750), one angle for CD (650) because its boards were fixed, three wings width of the foot of MB whereas, for CD, one share width (35cm) and two soil types (cultivated and uncultivated). CD could not penetrate the uncultivated soil more than 25cm so that there was one operating depth. The results of the experiments showed that SR for MB decreased as the operating depth, the angle between the boards and the width of the wings of the foot in both soil types were increased. Specific resistance (SR) for CD also decreased as the operating depth increased in the cultivated soil, but in the uncultivated soil, CD could not penetrate the soil more than 25cm. SR for MB was lower than that for CD for all operating depths, the angle between the boards, the width of the wings of the foot in both soil types. SR for MB and CD in the cultivated soil was low compared to uncultivated soil. The soil type decreased SR for MB more than the operating depth, the angle between its boards and the width of its wings. On the other hand, the angle between its boards reduced SR more than the width of the wings and the operating depth. MB surpassed CD in giving lower SR and that means the field performance of MB was higher than that for CD.

The draft force of the movable boards ditch opener (MB) was compared with that of the conventional ditch opener (CD). The parameters of the experiments were three operating depths (30, 40 and 50 cm), three angles between the boards of MB (45, 60 and 75º), the angle of the boards of CD was constant (65º), three wings widths of the foot of MB whereas, one share width (35cm) for CD and two soil types (cultivated and uncultivated soils). The texture of soils was silty clay. The results showed that MB can penetrate the soil to the required depth easily and its draft force requirements were lower than that for CD for all operating depths, angle between the boards and in the cultivated and in uncultivated soils. Whereas, CD could not penetrate the soil more than 25cm in the uncultivated soil that its draft force higher than that for MB for operating depth of 30 and 40 cm and for all angles between the boards but the contrary occurred with operating depth of 50cm. The draft force requirement of MB increased slightly with the angle between the boards but it MB increased considerably with increasing wings width of the foot. However, the wings of MB required less draft force than the share of CD which its width was 35 cm (constant width). MB surpassed CD in the field performance, it required less draft force and it could penetrate the soils easily.

A field experiment was carried out in silty loam soil at Agricultural research station, College of Agriculture during the corn growing season of 2015. The aim of study was to determine the effect of manure (cattle residues) levels (0, 20 and 40 ton ha-1), the depth of manure application (10, 20 and 30 cm), and the method ofmanure application (mixing with soil and subsoil laying) on soil bulk density and soil water content. The manure was added at certain treatments by using a ditch opener and manure laying machine which was designed and manufactured in the Agriculture Machines and Equipment Department, College of Agriculture, University of Basrah in 2015. The field was plowed perpendicularly, and the treatments were arranged in RCBD with split-split plot design with three replicated using drip irrigation system. Corn (Zea mays L.) seeds were planted on the manure rows. All plots received NPK fertilization with the same levels. At the end of growing season, soil samples (0-30 cm) were collected to examine soil bulk density and soil water content. The results showed that, lower bulk density and higher water content were obtained at level of 40 ton ha-1compared with the levels of 0 and 20 ton ha-1. The soil bulk density decreased from1.23 to 1.20 Mg m-3 and the soil water content increased from 26.33 to 30.23 % whenthe depth of application increased from 10 to 30 cm. Mixing manure with soil resulted in lower value of bulk density and higher value of water content compared with subsoil laying method. Mixing manure with soil down to the depth of 30 cm amount of 40 ton ha-1 improved the soil bulk density which reached lower value of 1.14 Mg m-3 and soilwater content increased to 36.19% among all other treatments.

SUMMARY This research was conducted on 2WD and 4WD tractors to determine the draft force ranges at which these tractors work at their maximum traction efficiency. Massy –Ferguson tractor of 2WD and 4WD type was used in the experiments. The total weight of the tractor is 48.85kN. The weight acting on the rear and front wheels is 34.63kN and 14.22kN respectively. The rated engine power is 95kW. The experiments were conducted using four tractor forward speeds G1(0.39), G2(0.51), G3(0.72) and G4(1.20) m/sec and six operating depths (10, 20, 30, 40, 50 and 60cm) for the plow which used to load the tractor engine. The results showed that the maximum traction efficiency of 2WD and 4WD tractors are 0.72 and 0.79 which occurred at traction wheels slip of 12% and 7% respectively. The draft force range of 4WD was wider than that of 2WD which gives 4WD tractor superiority on 2WD tractor. These draft force ranges are 15-30kN and 12.5-32.5kN and these ranges occurred at wheels slip ranges of 10-30% and 5-19% for 2WD and 4WD tractors respectively. The optimum traction efficiencies ( the optimum tractor performance) are 0.78 and 0.85 and they occurred at wheels slip of 17% and 8% and at draft force of 22kN for 2WD and 4WD tractors respectively. The maximum value of P F increased as the tractor forward speed increased for both tractors but this maximum PF provided lower draft force which means the tractor can not pull wider implements or machines working at greater depths but at lower forward speed the situation is better. For lower forward speed (0.39 m/sec) the draft force at which the maximum PF occurred at is 29 kN and 34 kN for 2WD and 4WD respectively. When the forward speed increased to 1.20 m/sec the draft force decreased to 23kN and 28kN for 2WD and 4WD respectively. The results showed clearly that 4WD surpassed in performance 2WD. it is more efficiently in using the power at the traction wheels as draft force increased with less power losses through the wheels slip and the rolling resistance and that can be seen from the difference between Pd and PF. The power at the traction wheels (Pd), the weight of the tractor (Gt) and the tractor forward speed (Va) were connected in equation for 4WD and