Variable depth cultivation: updates and new insights

26-09-2023 | Crop solutions | Article

Variable depth tillage comes within reach of an increasing number of implements ánd farmers. Research shows the biggest gain is reduced fuel consumption. But there’s much more to it.

An increasing number of cultivators, (disc) harrows, vertical tillers and even deep rippers is capable of adjusting the working depth and/or the intensity on the go based on varying soil conditions and parameters. A means of working mostly referred to as variable depth cultivation (VDC), variable depth tillage (VDT) or variable intensity tillage (VIT).

It allows for tuning for example coulter disc gang angles and machinery working depths to varying soil properties and types, slopes ánd to compacted areas. With the help of soil scanners or sensors, the tillage intensity can be varied automatically or if needed kept constant.

Keeping working depths constant

Topcon for instance, now also fits its well-known Norac ultrasonic boom height sensors to cultivators and disc harrows to maintain a constant working depth irrespective of uneven surfaces and bumpy fields. Two or four such sensors suffice depending on the length of the machine. Unnecessary deep working is prevented and that helps save fuel. Topcon’s technology doesn’t allow for working with prescription maps (yet).

Keeping working depths constant and vary them is possible with both Case IH AFS Soil Command and John Deere TruSet Active. The latter was introduced late last year and uses an ultrasonic sensor to measure the frame height and tillage depth of certain cultivators, disc harrows, mulch finishers and vertical tillers. It also adapts for mainframe wheels sinking into softer soils and building up mud. TruSet Active is compatible with other tractor brands as well.

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Since 2018, Topcon also fits its well-known Norac ultrasonic boom height sensors to cultivators and disc harrows to maintain a constant working depth irrespective of uneven surfaces and bumpy fields. - Photo: Topcon

Specialists rule

Although the number of VDC capable implements and machines is on the rise, a few specialist machinery manufacturers in Australia and the USA have picked it up early. Such as Gates Manufacturing in North Dakota with their Dynamic Adapt Soil Conditioning system. It uses photo-based sensors to monitor and adapt the gang angle of Gates’ disc harrows on the go to the desired soil to crop residue ratio. Gang angles adapt in steps of 0.5 degrees and between 0 and 15 degrees.

Summers Manufacturing, also from North Dakota, enables gang angles between 0 and 19 degrees for the same reasons. Their iControl offers memory positions for the various gang angle. Canadian research has shown that fuel consumption decreases by 17 percent after adjusting the gang angle by 6 degrees.

Australian manufacturer Davimac Group in New South Wales manufactures the Agrowplow AP82 deep ripper with a hydraulic level adjust lift. This enables depth and angle control from the tractor allowing operators to adjust to changing soil conditions.

The Austrian Innovation Farm in Wieselburg investigated how much fuel is saved with a 4-meter-wide Lemken Karat 9/400 KA cultivator by varying the working depth according to a prescription map. - Photo: Florian Krippl

Fuel reduce as main research result

While experienced user Valentin Ratasich hasn’t determined the fuel savings of variable depth tillage, some parties did. Such as machinery manufacturer Lemken, who asked the Austrian Innovation Farm in Wieselburg to investigate how much fuel is saved with a 4-meter-wide Karat 9/400 KA cultivator by varying the working depth according to a prescription map. A TIM-suitable Deutz-Fahr 8280 TTV was positioned in front of the cultivator. The fuel consumption of a uniform working depth of 16 centimetres was compared to variable depth tillage between 12 and 20 centimetres. 75 percent of the field was cultivated shallow (12 – 16 cm) and 25 percent deeper (16 – 20 cm). 35 percent of the field was cultivated at the average working depth of 16 cm. This resulted in an average fuel saving of 14 percent (17.9 versus 20.7 l/ha). Working capacity increased by 5 percent.

British company Soyl compared the fuel costs of cultivating 30 hectares at a uniform working width of 20 centimetres with a variable working depth of 15.5 (15% of the surface), 17.5 (20%), 19 (45%) and 21 centimetres (20 %). This resulted in fuel savings of 19 percent.

Scan and act in one pass

Adjusting tillage depth to changing soil conditions and parameters requires site specific insights in those conditions and parameters. Soil maps, satellite data but also tractor fuel consumption or traction records and soil sensors can account for that. Such as the CNH/AgXtend SoilXplorer, Dualem 21S, Geoprospectors Topsoil Mapper, SoilOptix sensor and Veris MSP3/iScan. The SoilXplorer technologically equals the Topsoil Mapper and both are claimed to be the only sensors that can scan the soil and adjust tillage depths real-time on-the-go in one single pass. The Topsoil Mapper currently retails at € 28,000 and requires Geoprospectors’ Automatic Tillage Control (€ 7,500) to do so.

The sensor is actively used in Austria, Brazil, Germany, Romania, USA and other countries (see box ‘Gathering experience with variable depth tillage’). Finding Isobus certified equipment that can be controlled by the sensor, is made easy with the AEF Isobus database and its app (see box ‘Your gateway to Isobus certified machinery’).

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According to our knowledge, the Geoprospectors Topsoil Mapper so far is the only soil scanner capable of measuring soil parameters and operating an implement in the same pass. - Photo: Geoprospectors

Lemken iQblue connect

One of the certified tools listed in the database is Lemken’s iQblue connect. iQblue connect turns basically any existing plough or cultivator into a smart one capable of controlling certain hydraulics automatically. To do so, an Isobus TIM-certified tractor is required. TIM means Tractor Implement Management and enables implements and machines to control specific tractor functionalities such as the hitch, the oil flow and pressure, driving speed and start-stop. Not too many tractors are certified as such yet, but if you have one, iQblue connect lets you change a plough’s working width and a cultivator’s tillage depth automatically. How that affects fuel consumption is described in the box ‘Fuel reduce as main research result’.

Gathering experience with variable depth tillage

Austrian farm machinery dealer and farmer Valentin Ratasich has been working with the Geoprospectors Topsoil Mapper and Automatic Tillage Control in the past two years. “Why would you till complete fields at 30, 35 or 40 centimetres deep? That was our initial question. We are a machinery dealer and try and test the machines we sell on our own farm first”, he says. And so they did with the Topsoil Mapper in the front of the tractor in combination with a 3-metre wide Farmet Digger subsoiler in the rear as a substitute for the plough. Via Isobus, the Automatic Tillage Control functionality automatically adjusts the working depth depending on the degree of soil compaction. “We till areas that have become more compacted deeper and less compacted areas shallower. We normally do this in the autumn after harvest. The system allows you to set minimum and maximum working depths. For instance 15 to 20 centimetres. With the Farmet Digger, we are able to relief compaction while at the same time, we can turn the top soil and obtain a good seed bed.”

TSM ATC auf Steyr mit Digger. - Photo Valentin Ratasich

Since he started using the Topsoil Mapper after harvesting crops like barley, oil seed rape, rye, soybeans and wheat, Valentin noticed several changes in his fields. “We are still gathering experience with the technology but have noticed that fields can be worked and tilled more easily and we’ve also seen better capillary action. All in all resulting in higher yields. I suspect we also save on fuel but we haven’t measured that yet. In future we might use the technology to monitor the condition of the soil over the years.”

Your gateway to Isobus certified machinery

AEF TC-GEO cultivatoren The AEF Isobus database or the app is useful for developed to check for Isobus compatible tractors, implements, sensors, terminals and so on. Finding a variable depth tillage certified machine is easy. Log in to the database (free account required) and go to ‘Compatibility Check’ and select ‘Functionality’ in the drop down menu showing ‘Please choose’. Then select the ‘TC-GEO’ functionality and choose ‘Tillage’. Select ‘Other Tillage Equipment’ next resulting in a list of certified brands including AgXtend, Horsch, Kverneland and Lemken. Clicking on a brand forwards you to the brand’s certified tillage machinery. If you go back to the tillage page and select mounted of semi-mounted plough, you will find Geoprospectors’ Automatic Tillage Control respectively Lemken iQblue connect.