Productivity of Field-Grown Soybeans (Amsoy and Williams) Exposed to Simulated Acidic Rain

Abstract

An experiment was performed during the summer of 1982 to determine the effects of simulated acidic rain on seed yields of two commercial cultivars of soybeans grown according to standard agronomic practices. Plants were shielded from all ambient rainfalls automatically by two moveable exclusion covers and exposed to simulated rainfalls in quantities equal to the average amount of rainfall that occurs at the site. Seed yields of Amsoy cultivar exposed twice weekly to simulated rain of pH 4.1, 3.3, and 2.7 were, respectively, 3.0, 9.0, and 12.8% below yields of plants exposed to a pH 5.6 simulated rain. A treatment-response function of seed yield versus rainfall pH for Amsoy was y = 10.20 + 0.587 x and had a correlation coefficient of 0.96 (y is seed mass per plant and x is the pH of the simulated rain). For the Williams cultivar, seed yields of plants exposed to simulated rainfalls of pH 5.6, 4.1, 3.3, and 2.7 were 11.5, 10.5, 11.4, and 11.4 g, respectively. A treatment-response function of seed yield versus rainfall pH for Williams was y = 11.13 + 0.016 x which had a correlation coefficient of 0.038. Plants of Amsoy and Williams grown in plots adjacent to the exclusion shelters and experiencing ambient rain conditions had mean seed yields of 11.4 and 9.8 g per plant, respectively. Seed yield per plant was dependent upon the number of pods per plant because the number of seeds per pod did not vary among treatments of each cultivar.