8 Acta fytotechnica et zootechnica 1/2013 Mária KMEŤOVÁ, Peter KOVÁČIK, Marek RENČO The decrease of production of organic fertilizers, which started in Slovakia in the 1990´s, has currently negatively manifested in several biological, chemical and physical parameters of the soil. In many soils the content of mobile phosphorus and potassium has decreased (Gáborik, 2006), the content of plant growth regulators, organic chelating agents and organic substances, which are involved in the formation of humus, has also decreased (Kováčik and Halčínová, 2010). The ability of the soil to resist sudden changes of pH and the sorption capacity of the soils has decreased (Fecenko and Ložek, 2000). The bulk density of the soil has increased, water infiltration into the soil has worsened and the negative effects of water erosion have increased. The air regime of the soil has worsened and the heat capacity of the soils has decreased. The soil fatigue has increased (Lacko-Bartošová, et al., 2005). The microbial life diversity in the soil was reduced, which in some locations caused retardation of the decomposition of crop residues infected by pathogens and resulted in an increased need for pesticide applications. Less relatively stable organic bonds with heavy metals are created, which has resulted in increasing penetration of metals into the food chain. All these things resulted in the reduction of yield grown plants in companies with the lack of financial resources to buy direct and indirect fertilizers. In many cases the lack of their own, but also the lack of quality and affordable purchased organic fertilizers, resulted in increasing the number of cases of poor quality manure applications, and as a result does not only negatively influence the height and quality of yield, but when it is used at the wrong time and dose, it also has a negative impact on the environment. Less attention is devoted to the technologies of processing by-products of plant and animal production, organic and inorganic waste materials from different industries in Slovakia than in the surrounding countries. The result is a number of products produced on the basis of these substances, whose effectiveness varies significantly as a result of failure to comply with production technology, but also inaccurate definitions of the active ingredient. The use of organic fertilizers and crop residues in crop production has been a known activity for hundreds, even thousands of years (Lacko-Bartošová et al., 2005), thanks to new varieties, changing climatic conditions, new aims in cultivation (higher yields, better quality, maximum efficiency of production), new technologies of food processing and efforts for nature protection and sustainable agriculture, these „old“ materials and new technologies are nowadays a target of refinement and globally focused attention Acta fytotechnica et zootechnica 1 Nitra, Slovaca Universitas Agriculturae Nitriae, 2013, s. 8 – 14 THE EFFECT OF DIFFERENT DOSES APPLICATION OF DRY GRANULATED VERMICOMPOST ON YIELD PARAMETERS OF MAIZE AND POTATOES VPLYV APLIKÁCIE SUCHÉHO GRANULOVANÉHO VERMIKOMPOSTU NA ÚRODOVÉ PARAMETRE KUKURICE SIATEJ A ĽUĽKA ZEMIAKOVÉHO Mária KMEŤOVÁ, 1 Peter KOVÁČIK, 1 Marek RENČO 2 Slovak University of Agriculture in Nitra, Slovakia 1 Parasitological Institute of the Slovak Academy of Sciences, Košice, Slovakia 2 Both pilot experiments were carried out in the district of Veľký Krtíš. The experiment with maize was realized on loamy Luvisol (cadastre Opatovská Nová Ves), characterized by a medium N an , conforming P, good K content and neutral pH. The experiment with potatoes was realized on loamy Fluvisol (cadastre Malá Čalomija) characterized by a medium N an , very low P, good K content and neutral pH. The experimental site has a warm climate, with the warm and dry subarea and with mild winters. In the experiment with maize grown for grain were 4 treatments established – a control treatment and three treatments with dose increasing of granulated vermicompost (4.6; 9.2; 11.6 t.ha -1 , respectively), which supplied 57, 114 and 142 kg.ha -1 total nitrogen to the soil, respectively. The experiment was not irrigated. The experiment with potatoes included 7 treatments of fertilization. The first treatment was a control treatment, i.e., without the appliance of dry granulated vermicompost. In treatment 2 to 6 increasing doses of vermicompost (3.3; 6.6; 9.9; 13.2 and 19.8 t.ha -1 , respectively) were applied. Through the following doses of granulated vermicompost were applied to the soil 40, 80, 120, 160, 240 kg.ha -1 N. Not only was the granular vermicompost applied in treatment 7, but also the industrial NPK fertilizer (150 kg urea + 200 kg.ha -1 NPK 15-15-15). The pre-sowing application of granulated vermicompost was significantly influenced the grain yield of maize, starch content in the grain, a thousand kernel weight and content of five observed macroelements (N, P, K, Ca, Mg). The grain yield was increased with the dose increasing of vermicompost. A thousand kernel weight, starch content and magnesium content parameters with the increasing dose of vermicompost were reduced. A dose of 4.6 t.ha -1 vermicompost seems like the most appropriate for the parameters of a thousand kernel weight, starch and magnesium content. The increasing doses of vermicompost significantly increased the yield of potato tubers, starch content and dry matter content in tubers. The application of granulated vermicompost reduced vitamin C content in potato tubers. The use of fertilizers resulted to increasing the nitrate content in potato tubers however the application of granulated vermicompost has increased the contents of nitrates to a lesser extent than the joint application of NPK fertilizer and granulated vermicompost. Keywords: granulated vermicompost, maize, potatoes, starch, vitamin C