The purpose of this investigation is to determine (1) the relationships among rates of application of sodium chloride on absorption of sodium and chloride by grasses, growth, and content of sodium and chloride under fairly high fertility and (2) the effect of complementary anions and cations in the rooting medium on sodium and chloride absorption. Field and greenhouse experiments were conducted with sodium chloride to study the effects of de-icing salts on grasses along highways. Rock salt was applied at 2, 4, and 6 tons/acre in 6 split applications during winter 1967-68 on all grasses seeded in 1966. In early spring, 50 lb/acre nitrogen was applied to half of each plot. The grasses were harvested in June and analyzed for sodium and chloride. Salinity fertility interactions were investigated in additional experiments with Kentucky 31 fescue in the field and with fertility levels after which a salt treatment was applied. A second field experiment with Kentucky 31 fescue show effects of potassium and nitrogen on uptake of sodium and chloride. The study shows a significant relationship between rates of applying rock salt and amounts of sodium and chloride in grass tops. Chloride accumulation in tissues was much higher than sodium. Sodium chloride depressed the top growth of grasses much more than the roots. Kentucky 31 fescue was more tolerant to sodium chloride than bromegrass, red fescue, and Kentucky bluegrass. Nitrogen minimized the yield depression and injury due to sodium chloride. However, high rates of nitrogen increased sodium and chloride absorption. Potassium reduced sodium uptake of grasses. Phosphate ions reduced chloride absorption. Potassium phosphate was more effective in retarding chloride uptake than calcium phosphate. There was an inverse relationship between chloride and phosphate content in tissues, hence, high soil phosphates should reduce chloride absorption. These investigations show there was less rock salt damage to plants with certain fertilizer salt nutrients than when rock was applied alone. Ions such as potassium and phosphates competed with and reduced sodium and chloride uptake, thereby improving plant survival. Before salt mixtures are used for de-icing, the effectiveness of salts as ice-melting agents, the costs of the material, and the polluting potentials must be considered.
Samenvatting