MINERAL NITROGEN CONTENT IN THE SOIL AFTER DIFFERENT FERTILIZATION IN ORGANIC FARMING

In organic farming is not possible to rely on plants fertilizing during vegetation according to their actual needs. The right crop rotation and harmonic nutrition are necessary for good and quality products. This is realized mainly by cultivating green manure crop and fertilizing by organic fertilizers. The goal of this long-term experiment is to evaluate the effect of different intensity and fertilization in organic farming with and without breeding livestock on content of mineral nitrogen in soil. There are four variants in this experiment: 1. Unfertilized control, 2. Green manure, 3. Green manure + renewable external sources (27 t/ha of compost + 14 t/ha of digestate), 4. Green manure + farm fertilizers (27 t/ha of manure + 14 t/ha of liquid manure). The result obtained from the experimental year 2016 show, that the best variant providing good supply of nitrogen during vegetation is combination with green manure and renewable external resources (compost + digestate). Soil in this variant contained around 83 kg/ha of mineral nitrogen after emergence of potatoes. Variant with green manure and farm fertilizers contained 77 kg/ha and unfertilized soil contained around 46 kg/ha of mineral N. Content of mineral nitrogen in the flowering, around 55 kg/ha, was also the highest on variant 3. The remaining variants had a similar nitrogen content in the soil, around 44 kg/ha.