Work­ing the land

The Kuhn Op­ti­mer 4003 is a com­pact trail­ing disc har­row de­signed for cul­ti­vat­ing at speed to a shal­low depth. Brent Lil­ley heads to New Zealand’s Whakatane re­gion to try it out

Farms & Farm Machinery - - Contents -

Kuhn Op­ti­mer 4003 disc har­row

While the weather has a big part to play in any crop­ping sit­u­a­tion, get­ting the ground worked up and then planted in a timely and ef­fi­cient man­ner also has a sig­nif­i­cant ef­fect on the out­come.

Stock­land Agri owner Nigel Timbs knows this all too well. Al­though he started out solely as a fenc­ing con­trac­tor in New Zealand’s Bay of Plenty re­gion, the busi­ness has grown to in­clude some agri­cul­tural con­tract­ing work and, more re­cently, con­tract maize grain grow­ing where he crops around 150 hectares of ground ev­ery year.

With a con­tin­ual ro­ta­tion of maize grown on fer­tile river flats, there is a large amount of stub­ble and crop residue that needs to be in­cor­po­rated back into the soil with a disc har­row after har­vest. This usu­ally takes place soon after har­vest so the ground can be left fal­low over win­ter be­fore be­ing ploughed and cul­ti­vated in the spring.

Last year, when look­ing to in­crease the ef­fi­ciency of the oper­a­tion, Nigel went in search of an up­grade for an older 3m Lemkin disc har­row that he had been us­ing.

He saw the Kuhn Op­ti­mer in ac­tion at a demo and, with the help of lo­cal dealer W.J. Dip­pie, it was soon added to an ever-grow­ing col­lec­tion of Kuhn equip­ment in the Stock­land

Agri yard that in­cludes a VM123 re­versible plough, HR3002 power har­row, and SD4000 drill.


The Kuhn Op­ti­mer 4003 is a com­pact trail­ing disc har­row that has been de­signed specif­i­cally for cul­ti­vat­ing at speed to a shal­low depth and in­cor­po­rate residues. To do this, it firstly uses large 510mm di­am­e­ter scal­loped discs set at ag­gres­sive op­pos­ing an­gles to cut into the soil. The 32 discs are ar­ranged in two gangs across the 4m width of the ma­chine and run on slim in­di­vid­ual car­rier arms that give plenty of clear­ance for soil and stub­ble move­ment through the ma­chine. Each disc is mounted to the car­rier arm on an in­di­vid­ual cast hub that houses a com­pletely sealed bear­ing unit, which is greased for life, sav­ing time and low­er­ing the main­te­nance re­quire­ments. Fairly com­mon, but still good to see in this ma­chine, is that the car­rier arms are mounted with rub­ber blocks sand­wiched in the clamps on the frame. This al­lows in­di­vid­ual move­ment to pre­vent dam­age if a solid ob­ject is struck. The over­all work­ing depth of the discs of the ma­chine can be varied any­where be­tween 30mm and 100mm. This is eas­ily changed with­out tools, us­ing a screw ad­just­ment stop­per that in­cor­po­rates a clever scale and a sim­ple pin-and-hole setup on the rear roller.


Set be­hind the discs is a row of light and ad­justable straight spring tines that fur­ther help to level and bury residues. Al­though they don’t look like much, it was sur­pris­ing to see how ef­fec­tive they were with­out block­ing up in the large amounts of maize trash.

The work­ing height is ad­justable, and the tines can be lifted clear of the ground if not re­quired. It uses a sim­ple pin-and-hole setup, and the de­sign clev­erly in­cor­po­rates a han­dle with enough lever­age to make it easy to lift the tines up and down when ad­just­ing them with lit­tle ef­fort.


All com­po­nents on the ma­chine are car­ried on a well-built, ro­bust yet com­pact main­frame, with large 400/55-22.5 flota­tion tyres that are used to lift the ma­chine out of the ground when turn­ing on the head­lands or for trans­port.

To keep the over­all trans­port width un­der 3m, there are outer wings on ei­ther side that can be hy­drauli­cally folded and car­ried ver­ti­cally.

Clev­erly, when the outer wings are in the work­ing po­si­tion, there is a choice on the fold­ing rams be­tween a fixed po­si­tion (to keep the ma­chine level and rigid), and a slot­ted hole (which al­lows the wings to move up and down fol­low the ground con­tours). It seems a good idea to have the choice.

Up at the front of the ma­chine is a solid two-point hitch that al­lows move­ment in all di­rec­tions. This hitch also al­lows for tighter head­land turns and means the ma­chine can eas­ily be lev­elled on the three-point link­age for a level fin­ish.

A tele­scopic draw­bar would be an im­prove­ment to the ma­chine, al­though not a prob­lem in Nigel’s sit­u­a­tion.

If you are run­ning wide du­als, the short draw­bar will limit the turn­ing abil­ity. A hose nee­dle keeps hoses and ca­bles out of harm’s way, and a well-placed stand makes it easy to un­hitch.

Al­though over­all the ma­chine is well built and tidy, a pass­ing com­ment on the day was that al­ready after only six months, the paint work had started to fade and show some blem­ishes.


Like most sim­i­lar ma­chines, the Kuhn Op­ti­mer of­fers a range of rear rollers to suit the in­tended us­age. There is the T-Ring roller, which is a wide-spaced, open press ring roller; the T-Liner, which is a deep ring steel drum roller; and the Pack­liner, which was fit­ted to Nigel’s ma­chine.

The lat­ter is a large, 600mm di­am­e­ter deep ring roller, which is coated with a hard rub­ber that en­ables it to work well in damp con­di­tions with­out soil stick­ing to it.

There are still scrap­ers fit­ted to keep it clean as well. It was rea­son­ably damp the day I was there, and the roller was han­dling it well. It pro­vides ex­cel­lent con­sol­i­da­tion across the width, and fur­ther breaks down clods in the soil to leave a firm level sur­face.


In­ter­est­ingly, Kuhn rec­om­mends around 200hp on the front of this 4m unit to achieve good for­ward speed. How­ever, on the day, a John Deere 7530 on the front with 180hp on tap seemed to be manag­ing a re­spectable for­ward speed of around 12-14 km/h and achiev­ing a good fin­ish – though this was on dead flat ground.

Hav­ing cov­ered close to 150 hectares, Nigel says he is pleased with the re­sults so far. He is pulling it with the same trac­tor and manag­ing sim­i­lar for­ward speeds – yet cov­er­ing an ex­tra me­tre of ground with ev­ery pass, low­er­ing run­ning costs, and im­prov­ing work rates.

It was also noted that the ma­te­rial flows through the ma­chine bet­ter, lead­ing to fewer block­ages, and residue breaks down no­tice­ably faster than in the past.


Ma­chines that com­bine shal­low cul­ti­va­tion and in­cor­po­ra­tion of crop stub­bles with rea­son­ably fast for­ward speeds and, there­fore, high out­put work rates have gained huge pop­u­lar­ity in Europe, and are ap­pear­ing more in Aus­trala­sia. I have been lucky enough to see roughly five ex­am­ples from dif­fer­ent man­u­fac­tur­ers over the last six months, and all had good points in their own right.

In my opin­ion, the Kuhn Op­ti­mer is a sim­ple yet re­li­able ma­chine that is easy to set up and sim­ple to ad­just. It achieved good re­sults in our test, and I was im­pressed to see this 4m model work­ing well be­hind a 180hp trac­tor. I guess, for me, the bot­tom line is that the owner Nigel is in­cred­i­bly pleased and im­pressed with the re­sults from the ma­chine.

The Kuhn Op­ti­mer 4003 com­pact trail­ing disc har­row Pho­tos by Brent Lil­ley

1: Stock­land Agri owner Nigel Timbs 2: The Kuhn Op­ti­mer is a sim­ple yet

re­li­able ma­chine

3: A sin­gle heavy-duty ram is used to lift the ma­chine out of work for turn­ing and travel

4: The row of fin­ger tines in front of the roller is eas­ily ad­justed by a de­cent han­dle along with a pin-and-hole setup

5: A solid two-point link­age hitch al­lows move­ment in all di­rec­tions and to be lev­elled with the height of the hitch

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