Effects of simulated acid precipitation on growth and nodulation of leguminous plants.

Abstract

Soil samples were collected from the Panther Lake, Sagamore Lake and Woods Lake watersheds of the Adirondack region of New York. The first two soils were from under coniferous canopy and the second from under a deciduous canopy. Agricultural soil was tested for comparative purposes. Simulated acid rain was applied to the soil samples for 14 days before seeds of Arlington red clover (Trifolium pratense L.) and Viking birdsfoot trefoil (Lotus corniculatus L.) were sown. Results show that, based on nodule numbers and depth, nodulation of birdsfoot trefoil was more tolerant to acidity than that of red clover. The depth to which nodulation occurred was reduced with decreasing pH of the simulated rain. Yield and nitrogen content of both plant species were significantly reduced in two soils. Under the test conditions, the legumes were stunted and neither species nodulated in Sagamore soil. The enhancement of plant growth and nitrogen uptake in both plants in Howard soil (pH 6.7) may be a reflection of improved nutrient availability arising from chemical action of the more acid solutions. (JMT)