Reducing the risks of contamination of agricultural land with toxic heavy metals during the application of organic fertilizers
Abstract
The risk of environmental pollution with organic livestock waste, especially cattle manure, which contains toxic heavy metals, is relevant for various countries of the world, including the United States of America, the countries of the European Union and Ukraine. Manure containing pollutants such as Cd, Pb, Cu, Zn, etc. is a much greater threat to agrobiogeocenoses and, in particular, to the soil. In the forest-steppe zone of Ukraine, an experiment was conducted on dairy cows for the production of ecologically safe milk. In the experimental groups, the animals were fed a special premix and injected with an antitoxic biopreparation, which increased the removal of heavy metals with excrement. The experiment was conducted in four farms with different herds of cows. At the end of the experiment, 10 samples of manure mass were taken from each farm (total of 40 samples), chemical analysis of the concentration of Cd, Pb, Cu and Zn was carried out by the method of Atomic Absorption Spectrophotometry (AAS-30 spectrophotometer). The content of feed in animal rations with exceeding the maximum allowable concentrations of heavy metals leads to their transition from the gastrointestinal tract into feces and urine and into manure, which, after disinfection in the manure storage, is introduced into the soil as an organic fertilizer for plants. The average concentration of Cd was 0.07-0.11 mg/kg, Pb 5.48-8.25 mg/kg, Cu 37.71-47.42 mg/kg, Zn 66.55-81.49 mg/kg. In order to prevent the ecological risk of soil contamination with heavy metals, it is necessary to establish the expediency of applying organic fertilizers to vegetable and fodder crops in each specific case, especially those that are fed to dairy cows. Farmers have difficulties in purchasing a sufficient amount of expensive mineral fertilizers, so they increase the use of available organic fertilizers, if their quantity is sufficient in the farm. At the same time, the introduction into the soil should be controlled, standardized taking into account the concentration of pollutants in the manure mass and the soil of agricultural land with simultaneous improvement of grinding and uniformity of distribution over the field. The use of modern equipment for crushing and spreading manure and scientifically based methods of its composting, growing vermiculture, synanthropic fly larvae or biogas production will contribute to the introduction of manure into the soil as an ecologically safe organic fertilizer, will have a positive effect on its mechanical and physico-chemical properties, will provide a good economic effective yield of crops, cows with ecologically safe feed, will reduce environmental risks of pollution of agroecosystems.