Implications of soil nitrogen enhancement on the yield performance of soybean (Glycine max) in cadmium-polluted soil

The growth, development and yield of important crop plants like soybean (Glycine max) are constantly under threat by continuous inputs of cadmium in the biosphere as a result of various industrial activities. This study investigated the level to which, addition of nitrogen fertilization can enhance plant survival, growth and yield development in a cadmium-polluted. Three accessions of Glycine max (TGm - 1, TGm - 2 and TGm - 3) were sown in a 12 mg/kg-cadmium polluted, which was thereafter amended with urea (FU), ammonia (FA), and ammonium nitrate (FN) singly and in combinations of equal proportions. A non-fertilized Cd-polluted soil and a general control constituted the negative and positive controls. Results showed that although N application did not enhance yield dispositions of soybean in Cd-polluted soil, significant impact on vegetative development was noteworthy. Compared to yield of control plants, cadmium pollution imposed a 26.1 % reduction in per plant yield in TGm-1, compared 1.71 % in TGm-3. Generally, addition of nitrogenous fertilizer further suppressed crop yield by as much as 80 % in plants sown in cadmium-polluted soil. However, application of ammonia fertilizer to TGm-2 improved its yield performances in the cadmium-polluted soil.