Case Study 2

650 ha farmed in partnership on medium to heavy soils with an annual rainfall of 640 mm. Rotation of first and second wheat followed by oilseed rape or beans. 10% setaside area sown with industrial oilseed rape. All crops are desiccated pre-harvest with glyphosate. Table 2 provides details of the relevant machinery. The present establishment system for wheat consists of a single pass with the Simba Solo with the subsoiling tines working to a depth of around 230 mm. This is followed after an interval by a spray with glyphosate and then the Freeflow tine drill sowing at a rate of around 200 kg/ha with grain having a 1000 seed weight of 49 g. Sowing is completed with a pass of the rolls pulled by a hired-in wheeled tractor. Slug pellets are applied pre- and post-sowing with a small all-terrain vehicle. Oilseed rape is normally established by broadcasting into the desiccated standing crop of wheat, or following a single pass of the Solo in front of the roll. Beans are sown in the same manner as wheat.

Machines relevant to the establishment, care and harvesting of the arable crops

Machine Wheel/Track gauge, mm Track/Tyre Width, mm Overall machine width, mm Operating width of implement, m
Claas Challenger 95E 2330 720 3050 N/A
Simba Solo - discs with integral subsoiler Wheels only in soil contact on headlands 4.5
Simba Freeflow tine drill Full width tyres 6.0
Simba Cambridge roll     8200 8200
Landquip sprayer on 1135 Fastrac tractor 2050 Front: 490 Rear: 560 2610 24
Claas Lexion 480 combine harvester 3040 720 3800 7.5
Merrick Loggin trailers 1850 300 2150 N/A
Renault 836 RZ tractor (hired for rolling) 1880 Front: 420 Rear: 520 2380 N/A

Here again we are presented with a dilemma because creating a 6 m system requires an additional machine to replace the Solo, which is acceptable, but we still cannot afford to lose the 1.5 m of harvesting capacity that such a system would entail. Ideally we need to bring everything up to 7.5 m to match the harvester and this could be achieved with the existing tractors, recognising that draught forces would be no greater than those already being experienced by the narrower equipment. However, before making this significant change to the system, it may be more appropriate to hire in a 6 m set of medium discs and set up a trial area with the harvester working at 6 m, as for the first Case study. Here again we can unload the combine harvester to the next permanent or ‘fuzzy’ tramline with no need for any modification. As there are fewer vehicles involved in this operation, the wheels of the most frequently used tractors cover a more confined area as indicated in the figure above. It is also easy to see that the situation could be improved if the gauge of the JCB and Renault tractors were increased slightly (circa 180 mm and 210 mm respectively) to fall within the tracks of the Challenger.

Moving to a 7.5 m system would involve a number of challenges. The next wider drill of the same model is 8 m, so this would need some rows removing and some rings would need to be taken off the roll if double working is to be avoided. The width of the sprayer would also need to be reduced to 22.5 m to match in with three passes of the 7.5 m wide equipment. Unloading the harvester into a trailer on the adjacent wheelway is still possible, (centre of unloading auger around 6.7 m from combine centre line, side of trailer 6.4 m from same line), but a retracting side extension to the trailer or some extension of the auger would be preferable. This would leave us with a system in which around 19% of the land is wheeled by the Challenger (2 passes) and around 15% by the JCB and Renault. It would not be economically viable to run this system without using ‘fuzzy’ tramlines, and the harvester wheelings are almost completely outwith these permanent wheelways. Again, the ideal would be to change the harvester onto tracks, or fit the narrowest wheels and only this latter is likely to be economically viable.