The influence of vegetation in riparian filterstrips on coliform bacteria:II. Survival in soils

Survival of total and fecal coliform bacteria was measured in the 0 to 5,5 to 15, and 15 to 30 cm soil depths at 1, 3, 7, 14, and 90 to 120 d after sw ine (Sus scrofa) wastewater application to riparian filterstrips in souther n Georgia during each season of the year. Vegetative treatments evaluated w ere: (i) 20 m grass-10 m forest, (ii) 10 m grass-20 m forest, and (iii) 10 m grass-20 m maidencane (Panicum hemitomon Schult.). During winter, spring, and summer vegetation type in riparian filterstrips did not affect surviva l of total and fecal coliform bacteria. Total and fecal coliform bacterial numbers were usually higher in the top 0 to 5 cm of soil than in the 5 to 1 5 and 15 to 30 cm soil depths in all treatments. Total and fecal coliform n umbers in the 0 to 5, 5 to 15, and 15 to 30 cm depths declined approximatel y 10-fold every 7 to 14 d after waste application in all seasons of the yea r. At 90 to 120 d after waste application, total and fecal coliform numbers in the three soil depths did not differ from riparian filterstrips that di d not have animal waste applied. Total coliform bacteria in the 0 to 5, 5 t o 15, and 15 to 30 cm soil depths correlated with temperature and moisture in a curvilinear relationship (r(2) = 0.80 , 0.77, and 0.64, respectively). Fecal coliform bacteria in 0 to 5, 6 to 15, and 16 to 30 cm of soil also c orrelated with temperature and moisture in a curvilinear relationship (r(2) = 0.56, 0.53, and 0.53, respectively).