L. Hadjinikolova, D. Terziyski, A. Ivanova
Abstract. . This study is related to the development of mineral fertilization schemes aimed at balancing the content and the N:P ratio in the water of carp ponds and its impact on main physicochemical and hydrobiological environmental factors. It was established that a triple introduction of mineral fertilizers in ponds with predetermined nitrogen and phosphorus ratio of 16:1 and the background level before fertilization of 0.52 mg.l-1 – 1.11 mg.l-1, inorganic nitrogen increased from 10.3 to 65.7 times which provides optimum average seasonal levels within 6.06 mg.l-1 – 7.04 mg.l-1 typical for application of mineral fertilization. Increase in the levels of phosphates was recorded in the 1st day after fertilization within 0.87 mg.l-1 – 1.15 mg.l-1, as the background level before fertilization was 0.05 mg.l-1 – 0.13 mg.l-1.