Response of Corn and Soybeans to Simulated Saline Aerosol Drift from Brackish Water Cooling Towers

Field studies were conducted on corn (Zea mays L.) and soybeans (Glycine max [L.] Merr.) for 8 weeks during each summer from 1973 to 1977 to acquire information on the response of these crops to saline aerosol deposition from brackish water cooling towers. The studies involved two sources of salts (NaCl and brackish water from the Unit No. 3 cooling tower at Chalk Point, Md.) and various salt deposition rates (0.97–22.24 kg ha⁻¹ week⁻¹). Soybeans exhibited greater sensitivity than corn to simulated saline aerosol drift early in their growth cycle, but corn yields were impacted more than soybean yields from the foliar salt treatments. Vegetative symptoms of salt injury on corn were progressively more pronounced as the plants matured than was the case with soybeans. Polynomial regression analyses of yields vs. salt deposition rates produced linear relationships for both crops. Corn yields were described by the relationship Yc = 97.9 − 1.94X and soybean yields by the relationship Yˢᵇ = 103.5 − 1.73X, where X equaled the rate of salt deposition, and yields (Y) were expressed as percent of nontreated controls. Changes in leaf Cl levels in corn in response to foliar-applied salts were described by the relationship Y = 0.20 + 0.07X − 0.001X², and leaf Na contents by the relationship Y = 0.099 + 0.024X. Changes in leaf Cl levels in soybeans in response to foliar-applied salts were described by the relationship Y = 0.059 + 0.073X + 0.004X² − 0.0004X³, and leaf Na levels by the relationship Y = 0.086 + 0.011X + 0.0006X², where X equaled the salt deposition rate (kg ha⁻¹ week⁻¹) and Y equaled the element contents (%). In an effort to explore methods for assessing the levels of crop yield reductions in areas where salt deposition is suspected but no control plants are possible, corn yields were described by the relationship Yc = 105 − 35.5X₁ and Yc = 102 − 63.7X₂, where Yc equaled the percent of nontreated controls, and X₁ and X₂ equaled the Cl and Na contents (%), respectively. Soybean yields were described by the relationship Yₛb = 104 − 20X₁ and Yₛb = 105 − 57.9X₂, where X₁ and X₂ equaled the Cl and Na contents in leaves, respectively.