COMPARISON OF TOXIC EFFECTS OF ALKALI SALTS (Na_2CO_3 AND NaHCO_3) ON SORGHUM GROWTH PARAMETERS AND SOIL CHEMICAL PROPERTIES

摘要

Soil sodicity is major threat to agriculture at arid and semiarid areas of the world, which increased due to agricultural lands irrigated with low quality of water. The aim of this study is to compare the toxic effects of two alkali salts on growth of sorghum (Sorghum bicolor L.), uptake of ion contents in leaves and soil properties. The experiment was treated with two alkali salts (Na_2CO_3 and NaHCO_3), each at two concentrations (60 and 120 mM) in addition to a control (no salt amendment) for ten weeks. Results indicated that both salts significantly (p<0.05) reduced the plant height (13-37), dry (1848) fodder biomass pot~(-1) (31-64) and chlorophyll content (31-60) over control. The content of nitrogen (N), phosphorus (P), potassium (K~+), calcium (Ca~(2+)), magnesium (Mg~(2+)) and K~+:Na~+ (77, 79, 47, 44, 74 and 86) reduced at higher salt concentration of Na_2CO_3 120 mM. Similarly, soil mineral nitrogen NH_4~+-N (8.3-1.13 mg kg~(-1)), NO_3~-(16.5-1.7 mg kg~(-1)), available P (10.5- 2.2 mg kg~(-1)) K (281-107 mg kg~(-1)), Ca~(2+) + Mg~(2+) (3.5-1.1 mg kg~(-1)), and K~+:Na~+ ratio (17.3-0.8) decreased, while soil pH and Na~+ (17 and 87) increased for the Na_2CO_3 120 mM. Our results suggested that sorghum plants are moderately tolerance at lower concentration and may not grow at higher concentration, and Na_2CO_3 is toxic than Na- HCO_3 salt.