Conservation agriculture and soil fertility

Soil can be thought of as the heart of the agricultural economy, the center of the circulation of matter and energy. It is the habitat of a multitude of animals, protozoa, fungi, microorganisms and enables the growth of plants that provide food for humans and animals. Living, healthy soil processes plant residues and livestock manure and acts as a filter for water purification. Soil fertility therefore depends primarily on ensuring the best possible conditions for the development of soil organisms, an appropriate soil reaction (pH), a favorable ratio between water and air, an optimal supply of nutrients and their mutual relationship.

Agrotechnical measures that affect the soil must ensure the growth of agricultural plants without damaging the vitality and fertility of the soil.

Among the most important measures for the sustainable improvement of soil quality are measures to improve soil structure and increase the proportion of humus in the soil. The proportion of plant residues and humus in the upper soil layer is particularly important: to increase the durability of structural aggregates and thus infiltration capacity and reduce erosion. This condition can only be achieved by using organic fertilizers/compost and by shallow, conservation tillage and by leaving at least some of the plant residues on the soil surface. Experience shows that with conservation tillage, where at least 30% of the surface is left permanently covered with plant residues, the physical and chemical properties of the soil change significantly after a few years. The bulk density of the upper layer increases noticeably, the proportion of medium pores increases, and the proportion of macro pores decreases. As a result, the water capacity of the soil accessible to plants increases by 15 to 40%. There are more so-called "bio-pores" (> 1mm), which are made by soil organisms (earthworms, dead roots). Plant residues on the surface, together with vertically oriented "bio-pores", increase the ability of water to infiltrate from the surface, which means that more precipitation water remains in the field, and less of it drains off the surface. It is important that the infiltrated water seeps into the depth more slowly through the soil profile, as the hydraulic conductivity of conservation-treated soils is lower due to the higher density of the soils treated in this way. Despite the fact that the soils are denser, their structure is more durable. Especially in the upper 10 cm, there are more stable macro-aggregates (> 200 µm), which improves soil aeration. Plant residues on the soil surface reduce the impact force of downpours, which is extremely important for preventing erosion and lateral losses of nutrients and pesticides. At the same time, plant residues on the surface reduce evaporation from the soil. The soil under the litter is cooler (by 3°C on average), which, together with the increased amount of water available to plants, can significantly affect greater biological activity in the soil over the summer (= reduced drought stress). Also, the cycle: drying - re-wetting of the soil occurs more gradually, so such soils crack less and lose less water through cracks from deeper layers.