The first description of the inhibition of plant growth by root secretions of other plants was given by de Candolle already in 1832. However, it was only in the thirties of the twentieth century that the more serious interest in this kind of biochemical, invisible influence of plants (but also fungi and plants) was taken. They were scientifically called allelopathy. Allelopathy in the garden was introduced by Ch. Molisch in 1937 in Jena. At that time he described what the first farmers and gardeners who consciously started to grow plants organically were observing and using in practice. They did not use mass-produced chemistry and avoided monoculture.
To achieve biodiversity in the garden, we should first of all avoid monoculture, i.e. growing the same plants on one field or a fragment of the garden especially on a larger area. Why? Because every horticultural monoculture, whether conventional or organic, is foreign to nature, contrary to the laws of nature, contrary to the principle of biodiversity.
Organic horticulturalists and organic farmers integrate nature’s diversity into their system and make full use of it. We grow a wide variety of plants, we use crop rotation, changing plants every year on different areas…”. Robert Rodale
Properly cultivated, healthy plants defend themselves against pests and diseases. Interestingly, as recently as 100 years ago, very little attention was paid in horticultural textbooks to attempts to control diseases or how to get rid of pests. The advice was mainly about correct cultivation, fertilization and nursing. Much information on this subject appears in new publications. Why? Because there is actually more organisms we call pests or pathogens.
Only biodiversity and the simplicity of cultivation guarantee that most diseases and pests are eliminated. If the gardener cares about biodiversity, life in the garden is in harmony, and pest and disease infestations are rare or absent.
Two types of biodiversity are important for maintaining balance and harmony in the garden (but also in the field or in the forest): biodiversity on the garden surface and biodiversity in the underground layer of the garden (soil). The harmony between them guarantees the health of the garden and thus the health and resistance of plants. There are more insects, animals and micro-organisms living in a biodiversity garden that are in balance with each other. Thanks to this, the massive occurrence of insects, referred to as pests, is difficult. Plant diseases are also reduced – healthy plants are much more resistant. Biodiversity above and below ground is achieved in different ways, but they are closely related.