INORGANIC N AND P LOSSES FROM VARIABLE AND CONSTANT INTENSITY RAINFALL SIMULATIONS

Authors: Franklin, Dorcas; Truman, Clinton; Potter, Thomas; Bosch, David - Dave; Strickland, Timothy - Tim; BEDNARZ, C - UGA

Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/6/2005
Publication Date: 11/6/2005
Citation: Franklin, D.H., Truman, C.C., Potter, T.L., Bosch, D.D., Strickland, T.C., Bednarz, C. 2005. Inorganic N and P losses from variable and constant intensity rainfall simulations [abstract]. ASA-CSSA-SSSA International Meeting, November 6-10, 2005, Salt Lake City, Utah. CDROM.

Interpretive Summary:

Technical Abstract: Current risk assessment tools have been developed, inpart, using information from simulated rainfall studies utilizing constant rainfall intensities. Our objective was to quantify and compare effects of constant (Ic) and variable (Iv) rainfall intensity patterns on inorganic nitrogen (N) and phosphorus (P) losses from a Tifton loamy sand (Plinthic Kandiudult) cropped to cotton (Gossypium hirsutum L.). We simulated rainfall at constant intensity and variable intensity patterns (57 mm hr-1) and collected runoff continuously at 5 min intervals for 70 min from both conventional (CT) or strip-till (ST) systems . No significant differences in total mass losses were evident for TKN-N or TKP-P from either rainfall intensity pattern after 70 min of rainfall. In contrast, total cumulative mass losses of dissolved reactive P (DRP) and NO3-N were greatest for ST-Ic, followed by ST-Iv, CT-Ic, and CT-Iv in diminishing order (69 g P ha-1 and 361 g N ha-1 ; 37 g P ha-1 and 133 g N ha-1; 3 g P ha-1 and 58 g N ha-1; 1 g P ha-1 and 49 g N ha-1). These results indicate that constant rate rainfall simulations may over estimate the amount of dissolved nutrients lost to the environment in overland flow from cropping systems in loamy sand soils.