Well-managed modern agricultural production is the result of many years of accumulated knowledge in the field of agronomy, which is based on comprehensive research in chemistry, microbiology, botany, plant physiology, soil science, plant pathology, herbology, entomology, breeding, and...and...and...much more. Increasingly, the issue of maintaining and enhancing soil fertility is coming to the fore - the land, the soil, is our main tool for feeding the population, for the life of nature in all its diversity.

Soil from a geological point of view has been created over millions of years, it has physical and mechanical properties, texture and depth of profile that we cannot influence, but on the other hand we influence its fertility, structuring and health by our active economic activities, so science is constantly researching and seeking new insights into soil biology. There are many new developments in humus theory that are being worked on and useful conclusions for practice and technology improvement are expected, as well as the development of new ones.

I read a couple of interesting articles recently, one of which started with "Anyone can throw manure." But the goal is to consistently care for soil biology to maximize its potential. The main concern should be creating space for the roots and conditions for active soil life. We call this 'soil management'.  The aim is an optimum water, air and temperature regime for the development of cultivated plants from seed to maturity.

THE SOIL IS MOST FAVOURABLE WHEN LIVING ROOTS DEVELOP IN IT. They are a source of food for the billions of micro-organisms in the rhizosphere by releasing sugars, amino acids, etc. into the soil.  Some authors even figuratively describe the process as the "milking" of the roots by soil-dwelling microorganisms. This is the main pathway for humus formation. The denser the root system in the soil, the longer the above-ground mass photosynthesizes and keeps the root active, the more intense the soil life. It used to be thought that active soil fauna resulted in a loss of organic matter due to the release of carbon dioxide. But it has now been shown that rich microbial life is crucial for humus building and for soil energy. Our soil must support the effectiveness of microbial life through the living roots within it and plant residues.

And here we come to the main question - what should we do in order to be useful to the soil and to restore it naturally, to actively build humus, which in turn serves our production and long-term soil improvement. It's not that complicated - simple things that we've known for a long time are good for the soil, but sometimes we turn a blind eye and try to trick it - it stays at our expense - at the expense of our soil.

1/ Diverse crop rotation - biodiversity, species diversity is the basis of good practices. Cultivation of crops with different root systems and different nutrient regimes; the rule not to dominate hoe crops where the soil remains bare for a long time; inclusion of nitrogen-fixing crops, etc.

2/ In cultivation, the principle applies - as little as possible, as much as necessary - i.e. according to the conditions, try to reduce the coarse intervention in the soil, but observe the specific circumstances and assess the soil-climatic conditions at the time for the main crop. There is a lot of discussion, research and experimentation on this topic, there are many new directions, techniques and technologies, but there are no definitive proven advantages of this or that technology, so it is best to flexibly apply and alternate or drop different types of seeding techniques over the years.

3/ Use organic fertilizer whenever possible - a good product can be a valuable source of nutrients and a soil conditioner; it is not the quantity but the quality that is important for activating soil life.

4/ And most importantly on the subject - a major tool for maintaining soil life is catch crops or cover crops. They are the ones that between harvest and a new growing season will feed the soil with active roots and contribute untold benefits to our fields.

We at LEADER CONSULTING are the first consultants on the subject of catch crops in Bulgaria. We have delivered many brochures, articles, seminars, demo trials and individual consultations since 2014 and we will continue to follow up for you new knowledge and scientifically proven ones that are applicable in practice. As a sales representative of the Austrian brand SAATBAU LINZ, we only import certified catch crop seeds into Bulgaria and are trusted by hundreds of farmers across the country. Because CATCH CROPS ARE ALSO A CULTURE - that is why we offer seeds with provenance and sowing qualities and always appeal to practice sowing with adequate equipment as for a complete crop in the rotation.

We have repeatedly pointed out the advantages and purposes of each plant used as a catch crop. The advantages of mixed catch crop societies are undeniable, but it is better, in order to avoid the grower encountering difficulties in practice due to lack of experience and giving up at the first hurdle, to build up the catch crop gradually depending on the soil, climate and crop rotation.

The main catch crops are spring frost plants. In recent years there have been mild winters when, despite not overwintering, many species persevered until spring. This winter, with the dry cold, everything froze in January. These are the two sides of the coin. On the one hand we want a nice long lasting cover all the way to spring, on the other hand it is easier for conventional technology when the cover dies back and the soil warms up quicker.

Some technologies are based on overwintering plants in order to sow in thick mulch. There are always points for and against. So we advise trying any new idea on a limited area before introducing it into the whole production. Above all, our advice is to progress in stages, building and improving with each move, so we will also learn from our own observations and analysis, and this is the surest way to seamlessly put new technologies into practice.

Catch crops are not just those we sow between 2 main crops. A catch crop can be in between the rows of a trench crop, an catch crop can be in a flush crop - theoretically under the right conditions many benefits can be derived from catch crops at any point in the farming year. It is a different question whether we are correctly assessing the risks and whether the benefits will outweigh or whether, given the conditions, we are making the wrong assessment and the investment will damage our crop. Ultimately we want to improve soil fertility for the sake of a better harvest, for the sake of the long-term health of our soil, but not at the cost of a failed harvest. Such self-serving exercises are not necessary from a common sense perspective.

Practically any deciduous plant could be a "catch crop" if it fulfils the most important functions and has certain properties: being fast-growing, being undemanding, having an active root system, having a fine above-ground mass, etc., these things have already been written. In a mixture, it is good to combine plants with different root systems that 'work' different soil layers. Generally speaking we are looking for soil structuring, organic enrichment, weed suppression and biodiversity.

Important groups of catch crops are A/ crucifers with their strong arrow roots and rapid growth B/ nitrogen-fixing leguminous plants C/ neutral plants that are not attacked by pests such as diseases and enemies D/ some cereals also work well in the soil such as rye, oats, some grasses, but the MAIN RULE IS NOT TO LEAVE SEEDS FROM THE PREVIOUS CULTURE AS A CATCH CROP as they become a breeding ground for diseases and pests that have lived in the crop and maintain the infestation until the following year. Unfortunately, this is widely practiced in Bulgaria and it is very difficult to explain to farmers the harmfulness of the practice, given that it is tolerated by the ill-conceived regulation on the matter.

There are also growers who want to have every weed they have read or heard from a touring lecturer from another continent, but we live in Europe and let us concentrate on what grows here and is sensible, readily available and proven effective and will not bring in unknown quarantine pests. Everything else is mostly about filling in and maintaining interest.

Our catch crops portfolio includes all the species that are most important for a complete catch crop coverage - forage turnips, meliorative turnips, sinapis, buckwheat, phacelia, oilseed flax, leaf peas, vetches, broad beans, many types of clovers, biomass rye, sand oats, etc.









In this case, to maintain the interest, we will focus on the less used catch crop - Sorghum × drummondii . Especially the hybrid Sorghum × drummondii has a very rich biomass and can give 2 or more cuts if needed. Sorghum × drummondii  is a heat-loving plant and at the same time very drought tolerant. This makes it very suitable as a summer catch crop. At low temperatures, even positive temperatures, Sorghum × drummondii dies and for those who want to get rid of the catch crop early is a suitable option. For other technologies it is better in mixtures with longer lasting plants. Its great advantage is its strong active root and participation in mycorrhiza, which makes it a very good species for building humus. Sorghum × drummondii  is also very good for fodder production and can be combined for example - a cut for fodder and a following undergrowth for cover.

          Sorghum × drummondii                                                        OIL-BEARING FLAX

Another lesser-known plant for green cover is OIL-BEARING FLAX. It has a deep and strong root, and its water requirement is not high, so it is very competitive in the field and despite its non-savoury initial development it suppresses weeds well. The flax is a highly adaptable type, which makes it suitable for both maritic and continental climates.

The topic of catch crops is not limited to these general, albeit important, clarifications. It is directly related to the application of diverse technologies that have yet to be perfected for mass practice and that science has yet to thoroughly address. Until then, let us at least take the first steps to help the soil stay alive and build up its humus, as we expect it globally to be a filter for water, a regulator of climate and a buffer for poisonous substances. And in the immediate term, it is our means of producing our daily food - literally and figuratively - the livelihood of the world's people and the basis of our microscopic economic unit that forms the meaning of our lives.

For this material we have used sources who have published their own articles on the pages of periodicals of SAATBAU LINZ
and Leader Consulting's work photos from client and partner fields.

Certified Agricultural Engineer Evelina Marinova

February 2022