Response of Corn and Soybeans to Soil vs. Foliar‐Applied Salts of Cooling Tower Origin

Abstract

AbstractField studies were conducted on corn (Zea mays L.) and soybeans [Glycine max (L.) Merr.] during 1976 and 1977 to acquire information on the response of crops to saline aerosol deposition near brackish water cooling towers in combination with salt accumulation in the soil.Salt treatments imposed included preplant soil applications equal to 0, 14, 28, 56, and 112 kg NaCl ha−1 and foliar applications of brackish cooling tower water as saline aerosol drift equal to 0, 34, and 68 L ha−1 d−1. Total soluble salt in the foliar treatments averaged 23 ± 3 g L−1, with average weekly salt deposition rates of 0, 3.8 ± 0.6, and 7.6 ± 1.2 kg ha−1. Information on elemental contents in leaves at flowering, leaf injury ratings, and grain yields were obtained. Information on extractable P, K, Ca, Mg, and Na plus electrical conductivity (EC) and pH of 0‐ to 15‐cm soil samples was obtained in October 1977 following two summers of treatments on the same plots and again in April 1978.For both crops, leaf Na and Cl, metabolic index, leaf injury ratings, and grain yields were significantly (P ≤ 0.05) affected by foliar salts in both years. However, soil salt treatments influence only leaf Cl contents and metabolic index values. Grain yields were reduced an average of 10 and 9% of controls at the highest foliar salt rate in corn and soybeans, respectively.Significant (P ≤ 0.05) increases in extractable Na in soils were found with foliar salt treatments. Increases in extractable Ca and pH (P ≤ 0.05) and K, Mg, and Na (P ≤ 0.1) were observed with increased soil salt rates. However, no differences were found among soil chemical parameters 8 months following the termination of the foliar treatments. The soils data suggest that salt deposition within 10 km of the Chalk Point cooling towers would cause minimal impact due to the sandy textures of the soils and annual rainfall in excess of 100 cm yr−1.