Agriculture Reference
In-Depth Information
Environmental Aspects Of Organic Farming
http://dx.doi.org/10.5772/58298
A different system of fertilization in conventional and organic farming can have both a direct
and indirect effect on soil organisms. The direct effect is related to the composition and the
amount of applied fertilizers and the indirect effect is connected with changes of physical and
chemical soil properties.
One of the basic principles of organic farming is the most closed nutrient cycle, minimal
nutrient loss and limited nutrient supply to the system. In order to maintain the soil production
capacity, it is necessary to replace nutrients drawn from soil by harvests and lost nutrients by
biologically transformed organic matter in the soil. Regular supply of organic matter into the
soil is ensured by crops grown in order to enrich the soil with organic matter (clover, catch
crops for green manure), crop residues, residues of cultivated plant roots and manure. Soil
organic matter serves as a continuous reservoir of nutrients and energy for the soil environ‐
ment. It is also a factor of soil environment stabilization. Soil organic matter is a source of
nutrients for grown plants, source of energy for soil microorganisms, improves physical and
chemical soil properties, water regime, increases decontaminating and buffering soil capacity
and decreases nutrient losses washed away from soil, increases antiphytopathogenic soil
potential and strengthens the plant immune system.
Growing crops without mineral fertilizers is possible under following assumptions:
•
consistent application of all manure
•
direct application of recycled biomass and by-products into the soil
•
compost production in compliance with the technological process
•
use of uncontaminated nutrient resources
•
use of peat and humic substances in order to improve habitat and nutritional status of crops
•
use of indirect fertilizers containing nitrogen fixating bacteria (free-living in the soil,
rhizobia) or bacteria that access e.g. S, P, K and other nutrients form soil reserves.
The function of soil organisms is for transformation of organic matter in the soil irreplaceable.
In the initial stage of organic matter transformation, zooedaphon participates in the destruction
of crop residues and in the production of organomineral components. The transformation
proceeds on depending on organic matter composition, edaphon activity and environmental
conditions in terms of mineralization and humification. For the humus formation, there are
important root exudates, roots of perennial fodder plants, legumes, manure and compost and
dead residues of zooedaphon. A ready potential source of nutrients in the soil is the primary
organic matter, root exudates and manure. Crop residues alone cover mineralization losses of
about 50%.
Of the total amount of organic matter, less than 10% is humified. The increase of the amount
of permanent humus in the soil is a matter of long-term (tens to thousands of years). Water-
soluble carbohydrates decay fastest, cellulose, hemicellulose and protein decay average
rapidly and lignins and pectins are the slowest. The rate of decomposition of different organic
matter sources is greatly different. Sustainable land management system assumes a balanced