Effects of Manure Application upon Water Quality of Surface Runoff from Rainfall Simulation Tests
Division of Environmental Engineering , Master of Science , 2005
Manure contains nutrients for crop growth; however, overapplication, with time, can result in excess nutrients in soil, which can subsequently be lost in surface runoff. The general purpose of this research is to study the effect of liquid hog manure, applied as an agricultural fertilizer, on water chemistry of surface runoff from rainfall simulation tests. Specifically the research focuses on runoff water chemistry comparisons between lands receiving hog manure at different rates, via different injection methods, and upon different slope positions. To examine these objectives, soil nutrient supply rates (P, NH4-N, and NO3-N) of the 0 – 5 cm depth of soil adjacent to rainfall simulation positions, and runoff water chemistry (TP, OP, NH4-N, NO3-N, DOC, Cl- and coliforms) during rainfall simulation tests were collected before and after manure addition. Generally, manure application did increase soil NH4-N and NO3-N supply rates, and runoff NH4-N concentration. Soil P supply rate and runoff TP concentration were not affected by the manure addition; however, runoff OP concentration at one site (Perdue) increased significantly due to manure addition. The manure treatments applied in this study did not cause any significant increases in fecal or total coliform in runoff from rainfall simulation tests conducted 7 – 8 months after manure application. None of the water quality parameters exceeded the Guidelines for Canadian Drinking Water Quality. Manure injection method (regular versus low soil surface disturbance) had consistent effects on runoff chemistry, but application rate did not. The regular disturbance method had significantly higher concentrations of water quality parameters than the low disturbance method. The position of the test on the slope did not result in any consistent trends in runoff chemistry, whether before or after manure addition. Foot slope positions had higher soil NH4-N supply rates than upper slope positions, both before and after manure addition. Soil NH4-N, NO3-N, and P supply rates between landscape positions were not likely influenced by manure addition. Regression tests between soil nutrient supply rates and runoff chemistry indicate that soil NH4-N supply rates are a good index to predict runoff NH4-N concentration, but soil P did not predict runoff P.