Digested in biogas plants organic waste is converted into biomass that contains considerable amount of nutrients and can be used as a fertilizer and fodder additive.
Humic materials generated during fermentation improve soil condition and minerals serve as energy source and nourishment for microorganisms, which support improvement of nutrient assimilation by plants. The main advantage of biofertilizer is the easily assimilated form of almost full nitrogen content and other nutrients contained in substrate.
Considerable advantage of using biofertilizer instead of manure fire fanged in natural conditions is the absence of helminthes eggs, pathogenic micro flora and weed seeds that are all destroyed during fermentation process.
Organic substances in biofertilizer
While there are suitable inorganic substitutes for the nutrients nitrogen, potassium and phosphorous from organic fertilizer, there is no artificial substitute for other substances such as protein, cellulose, lignin, etc. They all contribute to increasing a soil’s permeability and hygroscopicity while preventing erosion and improving agricultural conditions in general.
Organic substances also constitute the basis for the development of the microorganisms responsible for converting soil nutrients into a form that can be readily incorporated by plants.
Humic acids [15]
Humic acids are important organic substances contained in biofertilizer. They increase resistive capacity of plants to unfavorable environmental conditions: droughts, high and low temperatures, toxic substances (pesticides, herbicides, heavy metals), increased radiation. Humic acids promote increase in growth rate of plants, shortening of vegetation period earlier (by 8-10 days) ripening and yield increase of agricultural plants.
Humic acids content reaches 13% to 28% of volatile solid content of fertilizer and their concentration depends on the digestion temperature.
Improvements in soil quality
Humic acid content is especially important for soils of the Kyrgyz Republic that are low in humic content. Application of biofertilizer leads to fast humification of plant residues in soil, helps to decrease corrosion level due to formation of stable humus and increase nutrient content , hygroscopic, amortization and regeneration properties of the soil. It has also been noted that earthworm activity is increased through application of biofertilizer instead of manure [8].
Application of biofertilizer on alkaline soils leads to soil neutralization and increasing its moisture content which is especially important in drought-prone areas of the Kyrgyz Republic [17].