Ammonia Oxidizers in a Grazing Land with a History of Poultry Litter Application

Abstract

Poultry litter (PL) is widely applied on grazing lands in Georgia. However, it is not clear how its long-term use affects soil microorganisms and their function. We examined changes in activity and community structure of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in a grazing land with a history of PL application and compared it to treatment with urea ammonium nitrate (UAN). Soil samples (0-15 cm) were collected in 2009 (after 15 yr of PL application) and in 2013 (after 2 yr of no application). The abundance and community composition of ammonia oxidizers (AO) were determined with molecular techniques that targeted Nitrification potential (NP) was used for measuring their activity. Abundance of AO was significantly higher in PL (7.41 and 7.10 log copies g soil for AOB and AOA, respectively) than in UAN plots (6.82 and 6.50 log copies g soil for AOB and AOA, respectively) in 2009. This is consistent with NP, which was higher in PL (0.78 mg NO -N kg h) than in UAN (0.50 mg NO-N kg h) plots in 2009. The abundance of AO and NP decreased in 2013. There was no treatment effect on the composition of AO. Correlation analysis suggested that AOB were functionally more important than AOA, indicating the need to target AOB for efficient management of N in PL-receiving soils. Overall, the difference in nitrification between PL and UAN was mainly caused by the change in AO abundance rather than composition, and AO were not negatively affected by an increase in PL-derived trace metal concentrations.

Changes in microbial communities in soil treated with organic or conventional N sources

“…As such, the results clearly show that AOB, not AOA, were responding to high N input in the form of ammonium sulfate. It also suggests that AOB were mainly driving the process of nitrification at high N input (Mundepi et al., 2017; Ouyang et al., 2017). This was despite the numerical dominance AOA over AOB in all the treatments.…”

“…Ammonia‐oxidizing bacteria grow faster than AOA under readily available N source and hence their response to high N input in this study. Despite the predictable nature of their response to N input, understanding the dominant ammonia oxidizer groups in mediating nitrification under specific site and management conditions is required to formulate practical N management practices (e.g., use of inhibitors) to minimize N loss (Mundepi et al., 2017).…”

Yield and Nutrient Dynamics in Conventional and Organic Sweet Corn Production Systems

“…Land application of poultry litter can lead to detrimental environmental effects such as NO 3 contamination of groundwater (Bitzer and Sims, 1988;Liebhardt et al, 1979), production and loss of ammonia (NH 3 ) (Cassity-Duffey et al, 2014;Rothrock et al, 2010), buildup of heavy metals (Sheppard and Sanipelli, 2012), accumulation of P (Mundepi et al, 2017;Schomberg et al, 2009), and subsequent P loss (Kuykendall et al, 1999). Due to the difficulty of predicting the amount and timing of plant-available N, some common practices used by farmers include applying fertilizer 2 to 4 wk before planting and/or applying up to 50% more poultry litter than the recommendation (Boyhan et al, 2010).…”