Quality of Runoff from Plots Treated with Municipal Sludge and Horse Bedding

Land application of horse stall bedding and municipal sludge can increase runoff concentrations of nutrients, organic matter, and bacteria as well as steroidal hormones such as estrogen. Concentrations of materials in runoff from sites treated with animal manure can be reduced by aluminum sulfate, or alum [Al2(SO4)3•14H2O] treatment. The objectives of this study were to assess plots treated with horse stall bedding or municipal sludge for: (a) runoff quality [concentrations of nitrate nitrogen (NO3-N), ammonia nitrogen (NH3-N), orthophosphate-phosphorus (PO4-P), fecal coliform (FC), chemical oxygen demand (COD) and 17- β estradiol (17 β-E, a form of estrogen)]; (b) changes in runoff quality caused by alum treatment; and (c) time variations in concentrations of the analysis parameters. Horse bedding and municipal sludge were applied to twelve 2.4 × 6.1 m fescue plots (six each for the bedding and sludge). Three of the bedding-treated and three of the sludge-treated plots were also treated with alum. Simulated rainfall (64 mm/h) was applied to the 12 treated plots and to three control (no treatment) plots. The data were analyzed as originating from separate completely randomized, one-way designs with three replications of each treatment. The first design had treatment levels of bedding, bedding and sludge, and control, while the second design had treatment levels of sludge, sludge and alum, and control. The control data were common to both designs. The first 0.5 h runoff was sampled and analyzed for the parameters described above. Analysis parameter concentrations for the waste treated plots were generally lower than those previously reported for runoff after organic treatments. In some cases, concentrations were no different from the controls. Mass losses of all parameters were low and agronomically insignificant. Alum addition decreased runoff PO4-P concentrations and increased NO3-N concentrations but had no effect on concentrations of other parameters. A significant effect of alum addition on 17 β-E and COD concentrations was anticipated on the basis of previous studies; its absence might have been due to inadequate mixing or interval between addition and simulated rainfall. Relationships between concentration and collection time followed two patterns: (a) highest concentrations occurring during the first sample (two minutes following runoff initiation; NO3-N, COD, FC and 17 β-E) and (b) delay in peak concentration until four minutes following runoff initiation (NH3-N and PO4-P). The detection of different general relationships between concentration and time suggests that different mechanisms are dominant in transport of the parameters analyzed