Nutrient transfer associated with precipitation in plantations of eastern cottonwood (Populus deltoides)

Determinations of pH and annual atmospheric inputs of total N, P, K, Ca, and Mg were made in a 7-year-old plantation of eastern cottonwood (Populus deltoides Bartr.) located on the floodplain of the Mississippi River near Greenville, MS. Concentrations and quantities of P, K, Ca, and Mg in precipitation and throughfall showed pronounced seasonal patterns, generally being greater in summer than winter. However, there was little difference between precipitation and throughfall N regardless of season. Relative to foliar element content, nutrients were leached in the order K>Mg>P>Ca with 47.3, 6.7, 3.1 and 31.2 kg/ha, respectively, being transferred to the forest floor. These quantities are generally higher than those reported for other forest species. The pH of precipitation increased upon contact with the summer canopy; however, the presence of acid precipitation (pH<5.6) was found in only eight of the 54 rainfall events monitored. Quantities of precipitation intercepted by the cottonwood stand exhibited no seasonal differences.