Alum-Amended and Non-Amended Poultry Litter Impacts On Soil pH and Mehlich-1 Phosphorus On a Long-Term No-Till Rotation.

Continuous corn-wheat-soybean crop rotations on no-till land are common in the Mid-Atlantic. Poultry litter (PL) can serve as a fertilizer source, however, N-based application rates result in over-application of P. Aluminum sulfate (alum) has been used to reduce air ammonia concentrations in poultry houses and was shown to reduce water soluble P in PL. The objectives of this study were to determine impacts of fertilizer treatments for long-term no-till situations on soil pH and Mehlich-1 extractable P (M1-P) over time and at depth. Fertilizer treatments included 1) 0-P control, 2) P applied via triple superphosphate based on soil test recommendations (TSP), and N-based applications of 3) poultry litter (PL), and 4) PL amended with alum (PLA). Soil pH (0-5 cm) decreased in all treatments over time; however, trends showed PL and PLA had higher soil pH than the control and TSP treatments after 1 year. Soil pH at depth (averaged over treatments) indicated acidification of only the top 0-5 cm.  Mehlich-1 P generally increased over time in PL and PLA, and was greater than no-fertilizer and TSP treatments (157, 141, 62, and 67 mg P kg^-1, respectively) in 2011 due to N-based manure applications. Concentrations of M1-P were also higher in PL and PLA than control and TSP treatments at 5-15 cm, indicating P leaching. The 0-P control did not fall below 55 mg P kg^-1 during the study indicating soils testing “Very High” in P may take 10+ years for additional P fertilizer to be beneficial for crop production. In conclusion, fertilizer application above P crop removal can significantly impact soil pH and M1-P at depth in Mid-Atlantic no-tillage systems.