Organic fertilizers

Importance of organic fertilizers

The use of local organic fertilizers is the main method by which humans influence nutrient cycling in agriculture. Some organic fertilizers, such as manure, poultry manure, feces, and green fertilizers, represent the reuse of part of the nutrients previously taken from the soil and from fertilizers, including atmospheric nitrogen additionally fixed by nitrogen-fixing bacteria. The more fully the possible resources of organic fertilizers are used, the less the need for additional purchase of mineral fertilizers. Other organic fertilizers, for example, peat, municipal household waste, and sapropels, like mineral fertilizers, serve as an additional source of nutrients in the cycle in any agrocoenosis.

All organic fertilizers, upon their mineralization, serve as an additional source of carbon dioxide for plants, that is, they improve not only root but also air nutrition of plants.

Organic fertilizers serve as a source of energy and food for soil microorganisms, and many of them are themselves rich in microflora. Organic fertilizers are the most important factor in regulating soil fertility: the content of organic matter, mobile forms of nitrogen, phosphorus, potassium, calcium, aluminum, iron, manganese, and trace elements; acidity; cation exchange capacity; degree of base saturation; biological activity; and water and air regimes.

Organic fertilizers include:

• manure;
• beddingless manure;
• manure slurry;
• poultry manure;
• peat;
• straw;
• sapropel;
• industrial and municipal wastes;
• sewage sludge;
• composts;
• green fertilizers (green manures);
• vermicomposts (biohumus);
• humates.

The effect of organic fertilizers on crop yields is manifested over several years.

Under conditions of agricultural intensification, the reproduction of soil fertility and the creation of a positive or deficit-free balance of nutrients and humus are the most important tasks of agriculture. They are solved by the systematic, scientifically substantiated application of organic and mineral fertilizers in crop rotation.

World agricultural experience shows that a high standard of farming is associated with the accumulation, proper storage, and use of organic fertilizers.

Efficiency of organic fertilizers

The efficiency of organic fertilizers in crop rotation increases when they are:

• applied under row crops;
• applied under a cover crop with sowing of grasses in crop rotations with perennial legume-grass mixtures; the aftereffect of organic fertilizers will have a better effect on subsequent crops;
• used in combination with mineral fertilizers on humus-poor soils of light texture.

All organic fertilizers are characterized by a long-lasting effect. Therefore, when determining agronomic and economic efficiency, reliable yield increases are summed over all years, at least over 3–4 years. Costs for preparation, purchase, storage, transportation, loading and unloading operations, harvesting, and final processing should be distributed in proportion to the obtained yield increases for all crops that received these increases.

The economic efficiency of organic fertilizers depends on the distance of their transportation. For fertilizers diluted with water (semi-liquid and liquid manure, manure slurry, and effluents), it depends on dilution: the longer the transportation distance and the greater the dilution, the less profitable, and sometimes unprofitable, such a technology is. Even when transported through pipelines or when manure is used for fertilizing irrigation, the fertilizers are diluted with water during direct application: in the mixing chamber and in the transport flow of pipelines.

The dilution of manure, for example, during hydraulic flushing, and during storage requires the construction of storage ponds with good waterproofing. Therefore, economically, on farms and complexes it is advisable to obtain and store manure, rather than manure effluents.

The economic efficiency of organic fertilizers also depends on the market situation for agricultural products.

Maximum consideration of all economic factors allows the most justified determination of all available resources of organic fertilizers by crop rotations and non-rotation plots, and within them, taking into account the direct effect and aftereffect for the crops most advantageous in agronomic, economic, and environmental aspects.

The rate and degree of decomposition of organic fertilizers depend on the enrichment of soils with microorganisms, their composition and biological activity, as well as on the conditions determining their vital activity: soil structure and aeration, water, thermal, and nutrient regimes, and physicochemical properties. In a humid climate on heavy soils, shallow incorporation of organic fertilizers is preferable in order to accelerate mineralization.

The intensity of mineralization of organic fertilizers is determined by their biogenicity. Thus, manure is a biologically active substance; it is rich in microorganisms, and one ton contains up to 13 kg of living microbes. Peat, on the contrary, is poor in microorganisms and therefore slowly decomposes in the soil. Therefore, to accelerate the decomposition process, biologically active substances are added, for example, manure, manure slurry, and feces, that is, organic composts are prepared.

List of sources

• Yagodin B. A., Zhukov Yu. P., Kobzarenko V. I. (2002). Agrochemistry. Ed. by B. A. Yagodin. Moscow: Kolos.
• Mineev V. G., Sychev V. G., Gamzikov G. P. et al. (2017). Agrochemistry. Textbook. Ed. by Mineev V. G. Moscow: Publishing House of VNIIA named after D. N. Pryanishnikov.
• Niklyaev V. S. (2000). Fundamentals of Agricultural Production Technology. Agriculture and Crop Production. Moscow: Bylina.