Agriculture Reference
In-Depth Information
mineral fertilizers and pesticides. Soils with low humus content and light soils are relatively
more sensitive.
A serious problem on large areas, especially of arable land, is a water and wind erosion.
Organic farming has a positive impact on its reduction thanks to the more diverse crop
rotations with a higher share of clover and grass-legume mixtures, a higher percentage of catch
crops and underseeding prolonging the soil cover over the year, a lower representation of
wide-row crops (e.g. corn), a more intensive organic fertilization and other factors. Neverthe‐
less, a danger of erosion can occur also in organic farming (and sometimes even more than in
conventionally cultivated areas) in particular, because of more frequent mechanical tillage or
slower plant development due to a lower mineral nitrogen content in the soil. Structural soils
are well more resistant to erosion [50]. When comparing particular factors, we find that
positives predominate.
A quality soil ecosystem should meet following criteria:
•
water flowing out from the ecosystem should have such a purity that it is suitable for
drinking water treatment;
•
growth of crops and their composition in terms of consumption should be at an acceptable
level;
•
microbial processes in the soil should be natural, therefore, relationships between microbial
biomass, microbial activity and soil organic matter should be predictable;
•
the soil should not contain potentially toxic chemicals (organic and inorganic) in concen‐
tration that should affect the previous criteria;
•
physical soil properties should enable the normal function of the ecosystem.
1.2. Nutrient recirculation
In agricultural ecosystems, there can be the soil fertility increased by additional inputs such
as manure or fertilizer application. Plant nutrition within conventional farming is more
dependent on the input of nutrients in the slightly soluble form, predominantly from synthetic
fertilizers. A part of nutrients leaves the system as a loss. On the contrary, the natural ecosystem
fertility depends almost entirely on natural biological processes, i.e. nitrogen fixation and soil
organic matter mineralization. In organic farming, there is the concept of soil as a living system.
Therefore, the fertilization system is designed in order to respect natural nutrient cycle and
not to adversely affect complex biological processes which nutrient cycles are dependent on.
Organic approaches lead to a higher organic matter content in the soil while conventional
intensive farming on the arable land can lead to a reduction of this matter content. Assigning
of legumes and clover into crop rotations is of a considerable importance because of their
agromeliorative effect on the soil. The effect is manifested also on physical properties with an
effect on the soil bulk density, water holding capacity, increasing porosity, soil structure
stability, etc. The size of invertebrate organism population depends on the physical condition
of the soil. They usually require well aerated non-compacted soil with low density.
