“Not a single field on earth is homogeneous”

14-06-2018 | |
Photo: René Koerhuis
Photo: René Koerhuis

There’s pioneers and there’s (extraordinary) pioneers. Arable farmer Oliver Martin definitely is of the latter category. He uses one of the first Geoprospectors soil scanners ever produced, and his 160 hectares farm bursts with other high tech.

Upon arrival at the ‘Neuwiesenhof’ farm in Baden-Württemberg in southwest Germany, the first thing that catches the eye is a Fritzmeier Isaria crop sensor. It was just used to sidedress nitrogen fertiliser variable rate in winter wheat. “Shall I show you the rest of my precision farming equipment,” says Oliver Martin. The equipment includes an Amazone mounted sprayer, a brand-new Amazone Primera direct seed drill, a Claas Lexion combine harvester, an Amazone ZA-TS twin disc fertiliser spreader with Argus Twin radar system, a Lemken Karat cultivator and a Kubota UTV with Fritzmeier soil sampler and the Geoprospectors Topsoil Mapper soil scanner.

Oliver Martin demonstrates the soil scanner at a field next to his farm. While hovering it between 20 and 45 cm above the ground, the soil electrical conductivity (ECa and ECt) is measured to determine various soil characteristics. Photo: René Koerhuis

Oliver Martin demonstrates the soil scanner at a field next to his farm. While hovering it between 20 and 45 cm above the ground, the soil electrical conductivity (ECa and ECt) is measured to determine various soil characteristics. Photo: René Koerhuis

All machines are (made) Isobus compatible and capable of working variable rate (including the cultivator). “Some of the machines were modified on our request. Others we modify or upgrade ourselves to suit our needs. There’s not a single machine or tractor on our farm that wasn’t modified!” All tractors and the combine harvester are equipped with interchangeable Topcon RTK-GPS sets and electric auto-steering systems, and the combine harvester is (of course) equipped with yield mapping. He tries to apply controlled traffic farming (CTF) where possible and uses 21m wide tramlines for spreading granular fertiliser and crop protection. The spreading width was lowered from 24 to 21m to more accurately apply granular fertiliser. Crop protection is always done between 2 and 7am to avoid evaporation and drift as much as possible and to be able to apply just 70% of the standard doses of chemicals. And if the wind catches up, his weather station aboard the tractor tells him to stop spraying… “I can also use it if necessary to afterwards prove that I was not violating the environmental rules during spraying.”

This is the new design of the Topsoil Mapper soil scanner from Geoprospectors. Photo: Geoprospectors

This is the new design of the Topsoil Mapper soil scanner from Geoprospectors. Photo: Geoprospectors

Need to know

  • Despite of what many farmers think, there’s not a single field on earth that is homogeneous
  • Better quality and easier available satellite imagery offers much potential for yield potential maps and NDVI crop indices
  • Despite of crab steer, (very) wide tyres and pressure regulation systems on heavy machinery, (deeper) soil compaction occurs
  • Decreasing the tramline distance to more equally apply granular fertiliser can pay off in more uniform and easier to harvest crops
  • Controlled traffic farming (CTF) is quite difficult to practice on farms with relatively small and irregular shaped fields

Very heterogenous soils

The soil sample points on the 160-ha farm with an average field size of 2.03 ha and loess soil types differ from 24 to 94 with 100 points being the best arable soil type. “So, all my fields are heterogenous to very heterogenous and that triggered me to start with site specific application.” Ploughing was banned in 1988 and since 2015, where possible, direct drilling is used instead of mulch drilling. “In arable farming, the soil is the starting point of everything. If you know what happens there, you can act with the right measures. If you spoil your soil, it will reward you with homogenous and good quality crops.”

In order to understand what is happening in his soil, Mr Martin started searching for a soil scanner some years ago. “I wanted a continuous on-the-go soil scanner that did not necessarily require an extra pass over the field to avoid (extra) soil compaction. I also did not want it to require soil contact and I wanted to be able to use it at any time, including on frozen or snow-covered soil and in (very) dry and (very) wet conditions. When I read about the Topsoil Mapper (TSM) from Austrian manufacturer Geoprospectors somewhere in 2014-2015, so before it was officially introduced, I knew I wanted to have the TSM.” Geoprospectors was founded in 2014 and the TSM soil scanner was introduced at the 2015 Agritechnica exhibition in Hanover (Germany). Mr Martin currently deploys one out of three TSM scanners in Germany and out of 56 sold worldwide (see box below for more info).

Neuwiesenhof Farm
Name: Oliver Martin
Residence: Baden-Württemberg, Germany
Enterprise: On the 160 ha family farm, Oliver Martin, his wife and his father-in-law grow various types of cereals including winter wheat, oil seed rape, soybeans, summer barley, spelt, grain maize and alfalfa. The average field size is 2.03 ha and the soil type is loess. The farm currently deploys 1 out of 3 TSM scanners in Germany and out of 56 sold worldwide
FarmBlick: Based on the experience gathered and the equipment invested in, Oliver Martin (right) founded the precision farming advisory company FarmBlick in April 2017. Co-founder is business partner Marius Sauer (left). They advise farmers that are embarking upon precision farming, provide satellite-based yield potential maps, rent out their crop sensor and soil scanner and perform site specific soil sampling. The latter also relies on cooperation with regional soil sampling companies in Germany.

“I’m a data nerd”

If you were already amazed by the above, then you’re probably going to be flabbergasted when Mr Martin starts taking about remote and near sensing and data (processing)! “I would consider myself to be a data nerd.” Surprisingly enough, he uses satellite images instead of the soil scanner to create so-called yield potential maps. “The ESA Sentinel 1 and 2 provide very accurate 10x10m resolution images. I use radar infrared satellite images from the past five years. These are not for free, but worth the € 6/ha I’m paying.” With his own algorithms, the satellite images are processed into yield potential maps. Mr Martin can do this for any field on earth and as he points out: “Many farmers usually tend to think their fields are homogenous. But based on my experience, I can guarantee you that not a single field on earth is homogeneous!” The yield potential maps (standard) consist of five different zones between low yield potential, average yield potential and high yield potential. The zones are used to create variable rate fertiliser application as well as variable rate drilling maps. “My target is homogenous (quality) crops, saving on inputs not necessarily is. I apply them variable rate to match the site-specific yield potential. Experience shows that, based on a common 70 kg N per ha dosage, I for instance vary the application rate between 40 and 100 kg/ha and on average I apply 71 kg/ha. My profit/gain shows in the crops that are much more homogenous.”

During the growing season, Mr Martin uses the Isaria crop sensor, drones with a Parrot Sequoia thermospectral camera as well as satellite imagery (the NDVI-indices) to determine the site-specific dosage of sidedressing granular fertilisers as well as growth regulators. “I use the satellite generated NDVI-maps, since I experienced that crop sensors can be at their limits at the end of the growing season. This pays off during harvesting because the homogenous crop just requires one single optimal setting of the combine harvester. Therefore, I simply don’t need a cruise control option and I can even save fuel as well.”

Topsoil Mapper usage

The TSM soil scanner is used on the Neuwiesenhof farm to determine site specific soil texture, compaction and soil horizons, relative water content, organic matter content, and in combination with the soil sampler, the phosphate, manganese and calcium content in the top 110cm of the soil. The field maps created with the soil scanner are used to generate variable rate seed drilling maps. “In winter crops, I increase the number of seeds per hectare on parts with a low relative water content (equals lower quality soil types) to compensate for non-emerging seeds. In summer crops like seed grain maize, I use the opposite strategy as on the parts of the field with a relative low water content, water is going to be the limitation. I usually vary the number of maize seeds between 7 and 11 per square meter.”

The TSM is not (yet) used for variable depth cultivation at the farm. “Our three-point linkage cultivator is not perfectly suitable for that. A semi-trailed version would be more suitable.” The TSM is used on about one third (63 ha) of the farms fields. It was also used to determine the (deep) soil compaction caused by heavy slurry application equipment. “The compaction by self-propelled machines is so severe, even with lowest tyre pressures in crab steer, that I banned all slurry equipment from my farm. I use compost instead.”

“As the TSM soil scanner, compared to other soil scanners, measures the delta (or change) in soil conditions, it’s not necessary to scan fields more often than once every 5 to 7 years,” he concludes.

Understanding near surface structures

The young Austrian company Geoprospectors was founded in 2014. Its slogan is ‘understanding near surface structures’ and it offers solutions for this in agriculture and geophysics as well as in marine and air. “We wanted to collect data about soil conditions while performing any type of field operation but without contact to the soil,” says technical director Michael Pregesbauer. “In order to do so, we developed the Topsoil Mapper.”
The scanner works according to the electromagnetic induction principle (similar to the wireless charging of electric toothbrushes) and contains one transmitting coil and four receiving coils that receive the transmitted signals. “The induction principle works reliable in any type of soil and in any condition. Dry, wet, salty, frozen, snow on top, it does not influence the results.” Each of the reception coils covers 30cm of soil depth (20 to 110cm deep) while hovering the TSM between 20 and 45cm above the ground. This way, the soil electrical conductivity (ECa and ECt) is measured and processed into various soil characteristics including soil compaction and/or the depth of soil horizons, relative water content, as well as the soil texture (in soil classes). As metals close to the coils can influence the measurements, it’s necessary to use a non-metal construction to mount the TSM to the carrying vehicle. While calibrating the TSM, it takes into account any close metal parts of the carrying vehicle.
The recommended tramline distance space is 18 m. Larger distances are also possible but cause the resolution to worsen. At Neuwiesenhof farm, the common tramline distance is 6m, but also 27 and 33m distances were used. Driving speeds can be as high as 60 km/h (37,5 mph) without loss of resolution. This so-called TSM Basic version starts at € 26,500.

Variable depth tillage

Initially there was no intention of using the TSM for on-the-go variable depth tillage based on soil texture and compaction, but today this is also possible. If the implement is capable of doing so, even section wise variable depth tillage is possible while scanning the soil in the front of the tractor and till in the rear simultaneously. This TSM Pro version starts at € 32,000. Savings are said to be 6-7 litres of fuel per ha, a 20% increase in productivity and a reduction of wear and tear of the tillage equipment. At the Agritechnica 2017, an on-the-go variable rate seed control setup was presented and since recently, the TSM optionally comes as Isobus compatible. In February 2018, Geoprospectors signed an exclusive distribution partnership for a large number of European countries with CNH Industrial. As a consequence of this, the TSM will also be connected to CNH’s weather stations for which CNH signed a distribution agreement with Dutch AgTech company AppsforAgri (see Future Farming 1-2018).


René Koerhuis Precision Farming Specialist