Let nature do more work with regenerative agriculture

The current agricultural system is reaching its limits; agriculture faces a major challenge in achieving the long-term objectives for sustainable agricultural production. Arable farming must also eventually switch to a production system with a neutral or positive impact on climate, soil, water and biodiversity. One solution is more regenerative agriculture.

Minimal tillage

Stimulator of regenerative, agro-ecological and nature-driven agriculture, Ajaan Hijmans, co-owner of Kairos Regenerative Agri & Food Systems, researches the possibilities of regenerative arable farming at his own company in the Dutch village Zuidwolde, within projects and with growers in the area. Minimal tillage and keeping the soil covered are key. Hijmans invested in a direct sowing machine that allows sowing directly into grain stubble, green manure or crop residues without soil cultivation.

Hijmans compares plowing with demolishing a house. The plow breaks the aggregates built up by soil life into pieces.

Plowing is like demolishing a house

The extra oxygen that enters the soil stimulates bacterial growth. This then further breaks down the ‘cement’ that holds the soil particles together. This causes the structure to deteriorate even further. The adhesives are the most accessible food for the explosive bacterial growth. First, a mechanical breakdown of the soil structure takes place, followed by a chemical breakdown process.

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Keep soil life in good condition all year round

Keeping the soil covered, preferably with a diversity of living plants, is important to keep soil life in good condition all year round. Without diverse food, part of the soil life dies, less organic matter is built up and soil aggregates weaken. Moreover, with subsequent cultivation it takes longer before soil life can contribute to the mineral supply of the crop. Above-ground insects also find shelter there and can help control pests early in the spring.

Hijmans wants to minimize the use of fertilizer on his own plots. The minerals from this are too easily absorbed by the crop, so that there is little interaction between soil life and the crop. Soil life is not stimulated to release minerals from the soil that the crop can use.

Four to six years

Hijmans expects that it will take four to six years before a system works properly. That time is also needed to learn what works and what doesn‘t. During the first seasons, Hijmans noticed an increasing carrying capacity and faster water infiltration compared to loose soil.

In 2022, Hijmans conducted a trial with direct sowing of corn in a green manure. The previous autumn, a winter-hardy green manure mixture of rye and winter vetch was sown in strips and a strip with winter vetch alone using the direct seeding machine. This developed well, resulting in a large crop in the spring.

The idea is to sow the corn in this crop in one pass, without tillage. The first challenge is to determine the correct sowing time. The green manure must die. Knowing that the green manure can only be killed effectively in the generative phase, we waited until the rye was in bloom and the winter vetch was at least 75% in bloom. According to Hijmans, the timing is crucial. Sowing was possible at the end of May. Hijmans uses a crushing roller with Chevron blades based on an American model, a Roller Crimper.

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Effortlessly through crop residues

Thanks to the serrated cutting discs, the direct sowing machine went effortlessly through the crop residues, so that the seed landed properly in the soil. However, the corn developed slowly. Hijmans thinks that the cause must be sought in an adjustment that is still too shallow in the large mass of leaf rye, the drought and too little row fertilization. Possible negative allelopathic effects of rye on corn also play a role.

Vetch, which also provides nitrogen, seems better in combination with corn. The thick mulch layer ensures that annual weeds are well suppressed, retains moisture in the summer and is at the same time a slow-release fertilizer for the following seasons.

Direct sowing of winter grains

Another trial running this year is the direct sowing of winter wheat and winter barley in the crop residues of grain maize. So far the grains are developing well. Fertilization is one of the challenges in the system. According to Hijmans, it is an interesting quest to complete the entire system.