New Animal-Drawn Machine Concepts for Future-Oriented Agriculture – part 1

Crimper Roller SmP Kombi-Roll 3.0

by Paul Schmit of Luxembourg
Schaff mat Päerd

Facing the Future Challenges

Agriculture worldwide is currently in transition. Soil protection and regeneration or carbon storage are just some of the buzzwords currently being discussed by farmers, researchers, consultants, and politicians.

Climate change, its prevention and adaptation to what can no longer be reversed, will be one of the greatest global challenges for the next decades. After the very dry summers of 2018, 2019, 2020 and 2022, a pronounced drought also appeared anew in 2023 in many European regions. Later in the year, the long-awaited rainfall for forests and agriculture culminated locally in catastrophic floods.

Even as a low-input and low-impact agriculture, mainly following the farming practices of the bygone time, smallholders relying on animal traction must adapt their farming methods. This article is the first in a series of essays dealing with thoughts and new developments relating to future-oriented agriculture. This requires repeated field testing within a trial-and-error approach over several years, which means that the methods described here below are not the end of the story. At best, they represent the current state of the author’s empirical knowledge. These essays are intended to provide inspirations. Let’s move forward questioningly, together!

Closing a Vital Cycle Again

For the future, using animal traction in organic farming, to produce high-quality food, will not remain the only argument for an environmentally friendly cultivation method. Maintaining soil fertility, by using natural regulatory mechanisms of the ecosystem, will get more importance, but why?

Especially on vegetable farms, crop rotation is often characterized by a very low proportion of forage, if any. Therefore, just a low production of biomass remains on the farm, resulting in a poor on-farm supply of C, N, P and S. In addition, soil cultivation is often dominated by the most intensive, mechanical weed control.

Doing this, we humans have interrupted a vital cycle: With our crops, we take organic material from the field and do not bring it back there to rot. This has far-reaching consequences for humus reserves. This cycle must be closed again. Avoiding leaching of nutrients over the winter is another challenge, this is true not only in drinking water protection zones.

The time in which crops grow in fields or in our gardens is limited by the growing season. This is the time when plants are actively growing, flowering, and bearing fruit. Only a few crops can tolerate the cold season and therefore many arable lands lie fallow over the winter. Every gardener and farmer knows that beds or fields need to be prepared for the break in cultivation as the cold season approaches.

Traditionally, the soil is ploughed and organic fertilizer such as compost or manure is incorporated into the soil. But it is during the winter that most precipitation falls in Central Europe, as is the case in the northern hemisphere of our earth. Lower evaporation due to reduced solar radiation also helps water flow from top to bottom through the ground in the winter months. Excess nutrients that have not been absorbed by the crops can be washed out of the soil with the seepage water. Nitrogen but also phosphorus ends up in surface water and groundwater.

This can not only cause drinking water contamination, but far-reaching biological and chemical processes as well such as algae formation through eutrophication. Following a recent study in Luxembourg, the smallest country in the EU and home of the author, none of the surface waters are in good chemical condition anymore, according to the European Union’s demanding criteria. When it comes to groundwater, the conclusion is not much better: only half of the groundwater bodies are in good chemical condition. This is due to the multiple pressures on water resources caused by agriculture, but also urban planning and industry. Of course, many chemical agents also come from the atmosphere and can hardly be influenced through national politics, but the days are definitely over when the influence of agriculture could simply be glossed over.

These excess nutrients in the soil would be enough to grow another crop, the socalled catch crop. In autumn, fast-growing foundation species can absorb large amounts of mineral soil nitrogen. Especially nowadays, as increasingly warmer winters increase the risk of nutrient leaching. Furthermore, during the autumn and winter months as well as in early spring, the catch crop, also called intermediate crop, can form a protective blanket of living or dead plants on the ground. Hardy plant species protect the soil from the abrasive forces of rain and wind, avoiding soil erosion. Not only the regional rainfall distribution, but also our own management of it, will determine in the future the extent to which traditional mechanical planting, seeding and weed control will remain a strategy going forward.

Evergreen Farming

The organic cultivation of plants is based on the knowledge that a well-structured soil with sufficient organic matter and a diverse soil life is the basis for healthy plant growth. The care of the soil should therefore be the focus of ecological farming. Nutrients are supplied primarily through the supply of organic material, which is processed by soil organisms.

The microorganisms do not stand still during the break in cultivation. They continually ensure that easily leachable nutrients reach the soil by decomposing plant residues, breaking down permanent humus or dead soil organisms. This process is also known as autumn or winter mineralization. In recent years this has been particularly visible after the dry summers, not only on arable land, but also on grassland, when the mineralization started with the new rainfalls and still sufficiently warm temperatures.

In this so-called evergreen farming, which simply avoids keeping soil bare, deep-rooted species can even transport nutrients, translocated in the subsoil, into the topsoil. Catch crops that freeze over the winter are less suitable for the targeted nitrogen supply of subsequent crops as overwintering catch crops do. Insufficient freezing, due to the ever-warmer winters, can be another problem. Therefore, freezing catch cops are most useful for medium and low-feeding crops in the following year.

Of course, the catch crop mixtures must fit into the crop rotation and must not transmit any diseases to the following crop. When putting together the mixture, the aim is to achieve a high level of diversity of herb species, not only for optimizing the soil structure, but preserving the insect and bird world as well by providing a food source. Winter-hardy catch crop mixtures have a flexible sowing time from mid-September to mid-October and thus enable late sowing, which keeps the soil vegetated over the winter.

When working mainly with freezing catch crops, the nitrogen export associated with the harvest of vegetables can only be compensated for through the biological nitrogen fixation of legume green manures, also called cover crops and the farm’s own manure. Legumes in cover crop mixtures, such as peas, clover, or vetch, fix atmospheric nitrogen via their root nodules in symbiosis with rhizobia. In addition, they can break down poorly available phosphorus compounds in the soil.

Catch or cover crops are plants that are grown as “gap fillers” between two cash crops and replace fallow soil. However, growing these crops should be done with the same care as vegetables. Tillage for sowing catch and cover crops should be minimal but sufficient for their growth. Basically, every tillage breaks down humus. Growing intermediate crops always involves soil cultivation before and after. The correct use (working depth, timing, share types) determines the benefit or harm of the intervention in the soil. Cultivation should take place immediately after harvest, or as under-sown grain. The aim of incorporating green manure is to incorporate it as low-lying and mixable as possible without reconsolidation. The highly perishable biomass can otherwise lead to rot.

Photosynthesis is particularly efficient in summer. When it comes to outdoor crops, winter crops are generally not grown. Winter-hardy catch or cover crops should be sown here to optimize photosynthesis, sugar formation and thus the supply of soil organisms. In addition to the positive influence on the soil and the following crop, well-developed stands combat also weeds through light deprivation and nutrient competition, so that germinated weeds largely die without the opportunity to form seeds.

Catch and cover crops in vegetable production are usually seeded after early clearing cash crops in July to early/mid-September, allowing a maximum photosynthesis performance before the winter months. In Central-Europe, overwintering species can be sown until October. To ensure there is enough growing time, the planting in the following year should not take place before the end of April, which is usually the case as only then the ground temperature exceeds +8 °C. Depending on the subsequent crop, seed formation in the intermediate crop stands must be prevented by timely cutting or rolling, which unfortunately runs counter to the idea of biodiversity protection.

Sowing can be carried out by using standard grain seeding machines, provided the sowing rate can be reduced accordingly. For light germinators, no covering harrow should be used behind the coulters. Another option is to sow by hand followed by a roller or light weed harrow. The best results so far have been achieved with a so-called seeder-roller, which only lightly rolls the seeds with prismatic rings assuring the ground contact.

The Life Below Our Feet

To avoid soil erosion, not just the rainfalls and the soil covering, but also the soil structure plays an important role. Only so-called “tilth soil” has sufficient pores, to fill up with air and water and allowing good root penetration. However, tilth is not a physical process, but a primarily biological one. It is not the cultivation of the soil with agricultural implements or the frost over the winter that creates the soil structure, but rather the soil life based on material transformations and living structures. This promotes the resilience of the future cultivation system in times with heavy rain events.

Stable soil crumbs enable rapid water absorption and protect the ground against erosion. Intensive tillage mineralizes the soil nutrients and destroys the soil structure and the network of mycorrhizal fungi. Even if wind erosion is less when working with horses or other draft animals, due to less aggressive tools like rotary harrows, internal erosion in the ground can also be caused by repeated harrowing with spike or spring tooth implements.

In traditional crop cultivation, oxygen is introduced into the soil primarily through tillage and mechanical weed control. Oxygen stimulates the degradation processes in the soil and leads to a stronger and faster breakdown of nutrient humus and higher emission of carbon-dioxide by soil respiration. Carbon-dioxide is one of the greenhouse gases responsible for the climate change.

One strategy for (re)building humus quickly is to add large amounts of high-quality compost, such as is done in the so-called market-gardening. Here, the compost is often purchased from industrial composting plants. However, the carbon and nitrogen for the humus build-up should be generated on-farm. This can be ensured by using a sufficiently high proportion of perennial field feed or cover crops.

Humus-forming processes take place when soil life, consisting of soil fungi, bacteria, and earthworms, is fed by a variety of organic matter. The key to a functioning soil food web and humus buildup is permanent vegetation and as less tillage as possible. As a recent study of Luxembourg’s National soil laboratory has shown, non-turning tillage and no-till farming in conjunction with intermediate crops can increase humus levels in the topsoil, especially in the 0 – 15 cm range. Below, at 15 – 25 cm depth, depletion of humus occurs with a difference of +/- 0,3 % Corg. Here, ploughing would be of benefit, but reduced tillage still makes sense against soil erosion, and development of deeper layers of soil with roots by overwintering mixed cover crops can also lead to humus build-up.

Humus is subject to a constant build-up and breakdown process. The goal here is a positive balance. However, lush cover crops do not necessarily mean an upward leap in humus. It is not the above-ground mass that creates the humus, but the roots and their excretions. The root exudates of crop plants make up about 30 percent of the underground carbon and contribute 2.3 times more to soil organic carbon than the same amount of above ground biomass. A higher carbon input via roots, for example with cover crops, is more efficient than input via the soil, for example with straw. At the same time, deep rooting is a guarantee of making plants more resistant to drought.

Catch and cover crops must be easily degradable for microorganisms. How quickly the crop dies and releases the necessary nutrients for soil life and the following crop depends on the C:N ratio. The tighter it is, the faster the material will rot. For legumes it is 7:1 to 8:1, for crucifers it is slightly higher at 10:1, for grasses it is particularly high at around 12:1, and for grain straw can be even up to 100:1.

As mentioned above, ploughing distributes humus more evenly to lower soil levels. However, no tilth soil should be transported downwards, and lower layers upwards to then be broken up using energy-consuming methods. Rather, work should be carried out close to the surface in the tilth soil area and good tilth be expanded into deeper soil layers through intensive rooting over several years, using deep-rooted plants such as alfalfa, red clover, or broad beans.

The soil organisms, especially earthworms, need mulching material on the soil surface as food. The downstream microorganisms form stable clay-humus complexes and contribute to humus production. Some of these processes take place in an aerobic environment, close to the ground surface, others further down in an anaerobic environment. Ploughing suddenly turns this invisible world of microorganisms in the soil upside down and stops their activity for a longer period.

Organic direct sowing or planting means establishing a main crop through the mulch layer from a dead catch or cover crop without tillage. Ploughless tillage is the pinnacle of evergreen farming and long-term planning, as well as years of experience are crucial for success.

For beginners, the basic rules for their first steps can be summarized as follows:

• Cultivate the soil and use mechanical weed control as little as possible.
• Cover the ground as permanently as possible.
• Root the soil with living plants as much as possible all year round.
• Maintain the soil with the highest biological diversity possible.

So far for the theory…

In practice, terminating green manures before the next seeding or planting can be a true challenge, especially for organic farmers using no total herbicides. For organic farmers using animal traction even more, since the needed technology is often lacking.

Killing the cover crop vegetation by flat, full-surface undercutting at 2 – 5 cm depth, below the plant’s growth point, can be one strategy. Full-surface means that the soil is cut horizontally across the entire working width. However, this requires implements with finely adjustable working depth and sufficient weight to maintain the working depth consistently. Cutting through deep-rooted cover crops with equipment that is too light can be a torture for people and work animals.

Another option are crimper rollers, also called knife or mulching rollers. With the usually V-shaped blades, also called chevron-patterned blades, on a steel drum, the crop is crushed, and its growth is interrupted. At the time of full flowering, the plant has a strong flow of sap to the flowers to supply them and thus prepare for good fruiting. If the plant is bent and squeezed in various places at this point, this will damage the transport pathways. The plant then continues to pump against these injuries and exhausts itself in the process. As a result, she dies.

Furthermore, by pressing down the catch or cover crop evenly, an even mulch cover is created, also referred as in-situ mulching. Since the resulting mulch layer is only broken down, weed suppression is guaranteed for a long time as the weed germination is hindered. Furthermore, it retains moisture in the soil surface. A property that is particularly important for the success of the main crops in the increasingly drier summer months.

For so-called transfer or cut & carry mulching, mulch material is grown on another plot and, after cutting, is brought to the plot in question and evenly spread. The basics and newly developed technology for this cultivation method are presented and discussed in the following articles.

Combining the New With the Tried and Tested

After the very promising experiences with the CAD design of the mechanical selective weed cutting machine (see Small Farmer’s Journal 45-2), a crimper roller, to be newly developed for vegetable growing in smaller plots, was also completely designed on the computer by the European NGO Schaff mat Päerd before any work began in the workshops.

For row crops, row spacings of 60 to 75 cm have proven effective for horse work. Therefore, the knife roller should have a similar working width. Building on the good experiences with the self-cleaning crumbler roller SmP Kombi-Roll 2.0, the self-cleaning rubber ring roller Terraflow from the French manufacturer Otico was chosen as the basis for the crimper roller SmP Kombi-Roll 3.0. Only the original steel rings, made of galvanized steel and oscillating around the rubber rings vulcanized on a steel drum, were replaced by a new ring assembly with replaceable trapezoidal knives entirely made of laser-cut stainless steel.

Since 2009, Schaff mat Päerd has been testing traditional knife rollers with V-shaped blades on steel drums in various configurations. This in cooperation with the Italian animal-drawn implement manufacturer Equi Idea, who has already sold rollers to Italy, France, Luxembourg, and Belgium, mainly to vegetable and wine growers. These field trials proved that the knife spacing should not be too narrow to avoid smearing of the roller in slightly wet working conditions, which cannot always be avoided when working in early spring. Therefore, 12 blades per ring were chosen for the new ring assembly, resulting in 60 blades of 124 mm width each on the 600 mm wide rubber roller. Due to the comparatively small working width, the roller not only fits between the vegetable rows, but is, by its low draft force requirement, also suitable for smaller horses, which are often used in vegetable cultivation.

The two round traverses in the steel frame consist of a steel tube at the front and solid round steel bar at the back. This partly compensates the weight of the traction shafts assembly at the front and lowers the load on the horse’s back. To enable transport to the fields without damaging the knives, the frame is also equipped with two pneumatic tires, which can be raised and lowered using a hand crank. These wheels can also reduce the aggressiveness of the knives somewhat if less cutting effect is desired. For this purpose, the wheels are lowered during work.

The steel frame with V-shaped side parts and the geometry of the lifting axle were designed so that the draft line, starting from the collar, goes through the centre of the roller (in the working position) or the centre of the wheels (in the transport position). This balance of moments optimizes the draft force transmission to the implement’s load centre and prevents a pitching movement of the entire roller, because of the draft force, and by that additional strain on the horse’s back.

To minimize the rotation of the traction shafts around the longitudinal axis on uneven terrain, the shaft carrier is rotatably connected to the frame. This allows the roller to follow the unevenness without these being transferred to the traction shafts and the horse’s belly.

First Field Trials on Crimson Clover

The first testing under real working conditions of the new roller concept was carried out in cooperation with the Faculty of Agrobiotechnical Sciences of the Josip Juraj Strossmayer University of Osijek in Croatia. These field tests were carried out on an experimental plot in Požega on April 22, 2023, where the joint field tests with draft force measurements for stubble plowing also took place in 2022 (see Small Farmer’s Journal 46-2).

In contrast to the problems described above with water pollution in Luxembourg by increasing agglomeration due to immigration, Croatia is currently experiencing the opposite problem. Because young people are seeking their fortune in Western Europe, where wages and living standards are higher, there is currently a real exodus here since Croatia joined the EU. Emigration means a decline in the country’s economy and therefore the demand for agricultural products. As a result, the number of farm animals is declining and so is the production of on-farm fertilizers such as manure and compost. As part of a research project, the University of Osijek wants to develop environmentally friendly low-input farming practices for green manuring, including draft animal traction as optimized on-farm input.

Besides improving the carbon balance of the farming activities and soil fertility, the goal is also to decrease the country’s predominant dependence for synthetic nitrogen fertilizer imports, i.e. from the Ukraine, and the associated high emissions of carbon dioxide, nitrous oxide and nitrates in the atmosphere and waters.

In contrast to most of the other EU-countries, small and micro-farms still dominate the highly fragmented Croatian agriculture. The main cash crops are corn, soybeans, and sunflowers. Therefore, the research project tries to adapt new technology for green manuring before planting corn and this as alternative to using tractor powered choppers and mulchers. As cover crop, crimson clover (Trifolim incarnatum L.) with some volunteering oats had to be rolled down and partly cut for improving the later working in by conventional ploughing. The green manure was seeded in September 2022.

The height of the crimson clover was measured between 38 and 45 cm, and the clover’s stand was dense. Crimson clover was in a late vegetative stage with soft stems. The crimper roller was pulled by a Croatian Heavy Draft Horse mare of the smaller type standing 1,52 m high, followed by her filly.

The trials proved that the crimson clover can be efficiently laid down and chopped in just a single pass with the crimper-roller SmP Kombi-Roll 3.0. The required draft effort was rated in an acceptable range, as the light draft horse showed no sign of fatigue during the work. The roller’s weight of 200 kg has proven to be suitable for the small working width. All the plants were adequately bruised, but repeated rolling would also be possible. Chop lengths after a single pass of the implement were from 17 to 37 cm.

A corresponding report was presented at the International Symposium on Agricultural Sciences AgroReS 2023, hosted by the University of Banja Luka and taking place from May 24 to 26, 2023, in Trebinje (Bosnia and Herzegovina).

Living Up to Its Name

As the name SmP Kombi-Roll 3.0 suggests, the purpose of the crimper roller, as combination implement, should be as broad as possible and not just limited to intermediate crops. The pronounced summer droughts of the past years have shown that certain plants can overgrow on grassland or in forests. As deep rooters with a better contact to water reserves in the ground, even in long dry periods, these plants have a high level of competitiveness and push back the other vegetation.

A first test run took place on May 31th at a cemetery in Älmhult in Sweden. According to Swedish law, parishes are required to keep free cemetery areas available in the event of disasters or wars. Maintained as a park-like green zone, such an area also exists with the Norregårds Kyrkogård in the small industrial town of Älmhult in Southern Sweden.

The problem here, as in many other places in the province of Småland, is that lupine is constantly expanding. Mechanized mowing with tractor-driven flail mowers or walk-behind brush cutters during the summer, usually when the flowers are in full bloom, seems to promote the spread of the plant even more.

The test of the crimper roller SmP Kombi-Roll 3.0 should show whether its use here is more promising. The roller was pulled by a 15-years old Swedish Ardennes gelding standing 1,58 m high and provided by the full-time horse-entrepreneur Stall Backegård.

The first work results were very positive, all lupine plants were broken or cut. The cutting effect was more pronounced on older plants with thicker stems than on younger plants, which were more likely to just be bent over. A repeated rolling, after two to three weeks, would be helpful here.

The advantage of this working method, compared to the motorized cutting, is that it works almost silently and without interfering with the surrounding plants, as the grass is not affected. Especially in a place like this, this should be considered in future contracts.

On June 1st and 2nd, the crimper roller SmP Kombi-Roll 3.0 was tested on the farm of the Hälde Hästkraft work horse company in Vittsjö, also located in Southern-Sweden. Here, broad-leaved dock (Rumex obtusifolius) and bracken (Pteridium aquilinum) had to be rolled. Just like lupine, these two plants can spread invasively in pastures and forests. As a tap rooter with a root depth of up to 2 m, broad-leaved dock is particularly drought-resistant and spreads rapidly, especially after sward damages in winter and spring or in over-fertilized rank patches.

Here too, the plants in question were sufficiently damaged, although repeated operations are recommended depending on the weather. Especially on broad-leaved dock, the focus should be on early rolling, before flowering, to avoid seed formation and distribution. The roller was pulled by a 15-years old Northswedish gelding, standing 1,54 m high. Even when working in the forest, work was easy for the horse, because of the swinging suspension of the traction shafts.