Soil management

Fertile soil is of the principal value of every plant production. In conventional agriculture, favourable conditions for the growth and development of cultivated plants are created by intensive mechanical tillage and by the addition of easily available nutrients in the form of mineral fertilizers. Organic production is based on a completely different paradigm. Here, the soil is considered as a living organism and all measures are directed toward creating favourable conditions for the development of diverse microorganisms and fauna in the soil that will provide the necessary nutrients for cultivated plants through complex processes of organic matter production and decomposition.

Fertile and well-structured soils will provide optimal conditions for plant growth, which increases their resistance to pests. It is important to fertilize in a balanced way to ensure a sufficient amount of P and K, while N should not be excessive. Overabundant amount of N makes the crop tastier for insects. It causes high plant density and robust vigour. High humidity provides favourable conditions for the development of the disease. Moreover, it is demanding to monitor the diseases and pests’ symptoms and to apply plant protection products in such conditions, while it is harder for natural enemies to find pests. Therefore, in organic farming, manure is applied almost exclusively with organic fertilizers (stable manure, compost produced on one's own farm, etc.), which are gradually mineralized and mineral nutrients are released from them. Fertilization with organic manures ensures the maintaining and increasing of humus content, which is essential for fertility and microbiological activity of the soil.

Increasing the diversity of species in the soil is an important task in organic production because through their impact on nutrient circulation some of the soil microorganisms, natural enemies or small animals in the soil directly attack pests and destroy weed seeds. Tillage, and in particular the mixing of soil horizons, is reduced to a minimum to provide the conditions for soil organisms to be as favourable as possible. Wherever possible, the soil is maintained by cover cropping or mulching, thus creating a layer of soil with a crumbly structure, rich in organic matter and soil organisms.

Diverse cover crops are also habitats for natural enemies living above the soil. Cover cropping with fast-growing species that cover the soil is one of the most successful strategies for weed control especially in fields where crops are grown with large inter row distances.

Cover cropping with annual species (green manuring) can also be applied between harvesting and the beginning of new growing season/planting of new permanent crops. This is a good way to maintain the soil in areas where due to the small amount of precipitation is not possible to permanently grow cover crops together with perennial crops. Selection of proper species for green manuring can reduce the pest population left over from the previous crop, prevent weed growth and nutrient leaching in the soil. Their ploughing brings in fresh organic matter used to feed on microorganisms and other beneficial organisms in the soil.

Many of the benefits of crop covering, particularly the impact on the soil biodiversity improvement, are also achieved by mulching. In organic production, mulching with organic materials is applied, most often with straw or freshly cut grass. That kind of covering significantly affects the weed development, making it difficult for them to grow through the layer of organic matter and preventing the light necessary for germination.

Appropriate irrigation method can also affect the diseases development and should be adapted to specific crops. The amount of water in one round of watering, the irrigation frequency and technique can affect the spread of disease and the severity of the damage they cause. For example, if furrows are irrigated, it is suitable to water them more often with smaller amounts of water, while the sprinkler irrigation system is better to operate late in the evening or at night when dew is already forming. Considering disease prevention, the most suitable is localized irrigation (drip irrigation) where small amounts of water are applied to the plant root, while the aboveground plant organs are not moistened.