Eutrophication of Arable Soil: A Comparative Effect of Mineral and Organic Fertilizers Systems

Agrogenic eutrophication implies the artificial enrichment of soil with organic carbon and nutrients as a result of applying mineral and organic fertilizers to increase soil fertility and plant productivity. Eutrophication of gray forest soil, Luvic Retic Greyzemic Phaeozems (Loamic), has been created by annual application of increasing doses of mineral (N 90–360 kg/ha N, 75–300 kg/ha P 2 O 5 , and 100–400 kg/ha K 2 O) and organic (fresh cattle farmyard manure, 25–100 t/ha) fertilizers under plants of a five-field crop rotation for 9 years in a microplot experiment. The NPK amounts applied with manure are approximately equal to the corresponding doses of mineral fertilizers. In the systems of mineral and organic fertilization, the rates of soil enrichment with C org are 0.29–0.38 and 0.76–1.56 g/kg per year, respectively; with N tot , 0.04–0.06 and 0.06–0.09 g/kg per year; with available P 2 O 5 , 4–57 and 11–55 mg/kg per year; and with available K 2 O, 5–44 and 6–31 mg/kg per year, respectively. The doses of fertilizers in both systems are the most significant factor in the accumulation of nitrate nitrogen and available forms of phosphorus and potassium in soil, while the N tot content depends on the fertilization duration. The C org content in the soil with organic and mineral fertilizers depends on the dose of manure and the duration of NPK application, respectively. Soil eutrophication with mineral fertilizers is accompanied by a decrease in soil pH and eutrophication with organic fertilizers, on the contrary, leads to an increase in pH. It is emphasized that overfertilization and a long-term use of fertilizers are the main factors in the development of soil eutrophication and the concomitant change in soil pH.