Evaluation of sample preservation methods for poultry manure

Abstract

When poultry manure is collected but cannot be analyzed immediately, a method for storing the manure is needed to ensure accurate subsequent analyses. This study has 3 objectives: (1) to investigate effects of 4 poultry manure sample preservation methods (refrigeration, freezing, acidification, and freeze-drying) on the compositional characteristics of poultry manure; (2) to determine compositional differences in fresh manure with manure samples at 1, 2, and 3 d of accumulation under bird cages; and (3) to assess the influence of 14-d freezing storage on the composition of manure when later exposed to 25 degrees C for 7 d as compared with fresh manure. All manure samples were collected from a layer house. Analyses performed on the manure samples included total Kjeldahl nitrogen, uric acid nitrogen, ammonia nitrogen, and urea nitrogen. In experiment 1, the storage methods most similar to fresh manure, in order of preference, were freezing, freeze-drying, acidification, and refrigeration. Thoroughly mixing manure samples and compressing them to 2 to 3 mm is important for the freezing and freeze-dried samples. In general, refrigeration was found unacceptable for nitrogen analyses. A significant effect (P < 0.0001) of time for refrigeration was found on uric acid nitrogen and ammonia nitrogen. In experiment 2, the total Kjeldahl nitrogen and uric acid nitrogen were significantly lower (P < 0.05) for 1, 2, and 3 d of accumulation compared with fresh manure. Manure after 1, 2, and 3 d of accumulation had similar nitrogen compositions. The results from experiment 3 show that nitrogen components from fresh manure samples and thawed samples from 14 d of freezing are similar at 7 d but high variability of nitrogen compositions during intermediate times from 0 to 7 d prevents the recommendation of freezing manure for use in subsequent experiments and warrants future experimentation. In conclusion, fresh poultry manure can be frozen for accurate subsequent nitrogen compositional analyses but this same frozen manure may not be a reliable substitute for fresh manure if a subsequent experiment is performed.

Assessing refrigerating and freezing effects on the biological/chemical composition of two livestock manures

“…The contrasting results of previous studies (Van Kessel et al, 1999;Pan et al, 2009) may be attributable to the different manures tested but also demonstrate that impacts of different preservation techniques on manure composition are not well understood. Hence, we aimed to investigate how two commonly used preservation methods (refrigeration and freezing) affect manure samples from poultry and beef industries.…”

“…By contrast, refrigeration and freezing of manure had negligible impact on N and C turnover (Van Kessel et al, 1999). However, Pan et al (2009) reported that refrigeration of poultry manure drastically altered N composition with a 5-fold decrease and increase in urea-N and ammonium-N, respectively, compared with freezing, freeze-drying or acidification. Preservation methods were ranked in order of least to strongest impact on manure composition with freezing > freeze-drying > acidification > refrigeration (Pan et al, 2009).…”

“…However, Pan et al (2009) reported that refrigeration of poultry manure drastically altered N composition with a 5-fold decrease and increase in urea-N and ammonium-N, respectively, compared with freezing, freeze-drying or acidification. Preservation methods were ranked in order of least to strongest impact on manure composition with freezing > freeze-drying > acidification > refrigeration (Pan et al, 2009). However, freezing, which did not greatly affect manure composition, was still considered potentially problematic for subsequent manure experimentation (Pan et al, 2009).…”

“…Preservation methods were ranked in order of least to strongest impact on manure composition with freezing > freeze-drying > acidification > refrigeration (Pan et al, 2009). However, freezing, which did not greatly affect manure composition, was still considered potentially problematic for subsequent manure experimentation (Pan et al, 2009).…”

“…Consequently, manure samples are preserved prior to analysis by freeze-or oven-drying, refrigeration or freezing (Mahimairaja et al, 1990;Van Kessel et al, 1999;Pan et al, 2009). It has been well documented that the composition of manure changes with time during storage in the field (Markewich et al, 2010), while little is known about the effects on preservation methods on biological and physicochemical properties of manures.…”