Phosphorus Leaching from Soil Cores from a Twenty-Year Study Evaluating Alum Treatment of Poultry Litter.

Adding alum to poultry litter is a best management practice used to stabilize P in less soluble forms, reducing nonpoint-source P runoff. However, little research has been conducted on how alum additions to litter affect subsequent leaching of P from soil. The objective of this study was to evaluate the effects of alum-treated versus untreated poultry litter on P leaching from soil cores receiving long-term poultry litter applications. Two intact soil cores were taken from each of 52 plots in a long-term study with 13 treatments: a control, four rates each of untreated and alum-treated litter (2.24, 4.49, 6.72, and 8.96 Mg ha), and four rates of ammonium nitrate (65, 130, 195, and 260 kg N ha). One core from each plot received the same fertilizer as for the previous 20 yr, whereas the other was unfertilized in the study year, resulting in a total of 25 treatments. Cores were exposed to natural rainfall, and P leaching was measured for 1 yr. The average soluble reactive P concentrations in the leachate varied from 0.16 to 0.44 mg P L in fertilized alum-treated cores, whereas leachate from cores fertilized with untreated litter ranged from 0.40 to 2.64 mg P L. At the highest litter rate (8.96 Mg ha), alum reduced total dissolved P and total P concentrations in leachate by 83 and 80%, respectively, compared with untreated litter. These results indicate that alum additions to poultry litter significantly reduced soluble and total P fractions in leachate.

Reducing Phosphorus Runoff and Leaching from Poultry Litter with Alum: Twenty-Year Small Plot and Paired-Watershed Studies.

Treating poultry litter with alum has been shown to lower ammonia (NH) emissions and phosphorus (P) runoff losses. Two long-term studies were conducted to assess the effects of alum-treated poultry litter on P availability, leaching, and runoff under pasture conditions. From 1995 to 2015, litter was applied annually in a paired watershed study comparing alum-treated and untreated litter and in a small plot study comparing 13 treatments (an unfertilized control, four rates of alum-treated litter, four rates of untreated litter, and four rates of NHNO). In the paired watershed study, total P loads in runoff were 231% higher from pasture receiving untreated litter (1.96 kg P ha) than from that receiving alum-treated litter (0.85 kg P ha). In both studies, alum-treated litter resulted in significantly higher Mehlich III P (M3-P) and lower water-extractable P at the soil surface, reflecting greater retention of applied P and lesser availability of that P to runoff or leaching. In soils fertilized with alum-treated litter, M3-P was much higher when analyzed by inductively coupled argon plasma emission spectrometry than by colorimetry, possibly due to the formation of aluminum phytate. Indeed, alum-treated poultry litter leached less P over the 20-yr study: M3-P at 10 to 50 cm was 266% greater in plots fertilized with untreated litter (331 kg M3-P ha) than with alum-treated litter (124 kg M3-P ha). This research provides compelling evidence that treating poultry litter with alum provides short-term and long-term benefits to P conservation and water quality.

Use of selected chemical markers in combination with a multiple regression model to assess the contribution of domesticated animal sources of fecal pollution in the environment.

Human and animal wastes are major sources of environmental pollution. Reliable methods of identifying waste sources are necessary to specify the types and locations of measures that best prevent and mitigate pollution. This investigation demonstrates the use of chemical markers (fecal sterols and bile acids) to identify selected sources of fecal pollution in the environment. Fecal sterols and bile acids were determined for pig, horse, cow, and chicken feces (10-26 feces samples for each animal). Concentrations of major fecal sterols (coprostanol, epicoprostanol, cholesterol, cholestanol, stigmastanol, and stigmasterol) and bile acids (lithocholic acid, deoxycholic acid, cholic acid, chenodeoxycholic acid, ursodeoxycholic acid, and hyodeoxycholic acid) were determined using a gas chromatography and mass spectrometer (GC-MS) technique. The fecal sterol and bile acid concentration data were used to estimate parameters of a multiple linear regression model for fecal source identification. The regression model was calibrated using 75% of the available data validated against the remaining 25% of the data points in a jackknife process that was repeated 15 times. The regression results were very favorable in the validation data set, with an overall coefficient of determination between predicted and actual fecal source of 0.971. To check the potential of the proposed model, it was applied on a set of simulated runoff data in predicting the specific animal sources. Almost 100% accuracy was obtained between the actual and predicted fecal sources. While additional work using polluted water (as opposed to fresh fecal samples) as well as multiple pollution sources are needed, results of this study clearly indicate the potential of this model to be useful in identifying the individual sources of fecal pollution.