Influence of various forms of nitrogen fertilizers at productivity of mandarin Unshiu and red soils

Abstract

Red soils of humid subtropics of west of Georgia is poor with nutritious elements and that's why they need usage of mineral and organic fertilizers. The role of nitrogen included in organic substance of soil is strongly connected to this issue because usage of mineral fertilizers increases nitrogen mobilization. Our research has foreseen studying the influence of various forms of nitrogen fertilizers at qualitative indicators of mandarin “Unshiu” and productivity, as well as at increasing productivity of Adjara red soils. The results received from carried experiment verify the following: by taking Carbamide and ammonium nitrate in red soils, the humus consistency equaled to 6, 1–5,2% and consistency of hydrolysis nitrogen was 31,3–36,4 mg/100 g. By the usage of Carbamide the consistency of movable $P_2{O}_5$ equals to 78 mg/100 g; $K_{2}O$ - 33 mg/100 g; $MgO$ - 24,6 mg/100 g. By the usage of nitrogen fertilizers, the amount of nutritious elements $(N,P,K,Ca,Mg)$ in mandarin leaves and flesh are increased compared to the without fertilizer and background variant. To this aspect especially distinguished is the variants of taking Carbamide where the amount of common nitrogen is increased by 0,70% compared to the background and by 0,93% compared to without fertilizer variant. The increase of nitrogen at the variant of Carbamide at tangerine fruit flesh compared to background equaled to 0,21%. According to the average mass of one fruit, Carbamide variant is distinguished - 62,8 g. At nitrogen fertilizers variant, the consistency of skin in mandarin fruit equals to 31,3–32,7%, and the flesh equals to 67,3–68,7%. According to the juice consistency the Carbamide variant is the best as well, where the juice omission in the fruit equals to 44,9% and in the flesh it was 66, 4%.