A study was conducted for one year (2006) on a swine-row crop farm in central Iowa. The row crop operation consisted primarily of corn (Zea mays L.) -soybean (Glycine max (L.) Merr.) rotation. Swine production consisted of growing-finishing operation of 4,200 head. Swine waste was stored in pits for up to a year before being applied. Land application consisted of injecting the effluent into a slit approximately 20 cm below the soils surface. Eight plots (10 x 10 m) were established. Two plots were in a field in which swine manure effluent was applied in the fall to supply a corn crops N requirement (approximately 150 kg N ha-1). Four plots were in a field in which swine manure effluent was applied in the spring to supply approximately 100 kg N ha-1 with the additional crop N (50 kg ha-1) being supplied post-planting as sidedressed fertilizer. The last two plots were in a soybean field; one received swine effluent application in 2005 and the other did not. Soil core samples (0-15, 15-30, 30-45, 45-60, and 60-120 cm depths) were taken in May (planting time) and October (after harvesting). Soil samples from the top 22.5 cm were also collected biweekly throughout the growing season. These samples were analyzed for soluble components (nitrate, ammonium, SRP, pH, and EC), as well as exchangeable ammonium and Mehlich III extractable P. Plant samples were also collected and analyzed for biomass and N content.

"June 2009." "EPA 600/R 09/045." Includes bibliographical references (p. 13-14).