Effect of Packaging Materials on Nitrogen Retention and Ammonia Emission During Storage of Pelletized Poultry Droppings Amended with Single Superphosphate

Ammonia volatilization during storage of single superphosphate (SSP) amended pelletized poultry droppings reduces agronomic value by causing significant nitrogen loss and lowering fertilizer efficiency. This study evaluated the effect of packaging materials on nitrogen retention and ammonia emission of pelletized poultry droppings amended with SSP over six-months, using a completely randomized design (CRD) with three treatments (T1) – black polyethylene (300-gauge), (T2) – transparent polyethylene (300-gauge), and (T3) – high-density polyethylene (500-gauge), each with 4 replicates. The experiment was conducted at the Faculty of Agriculture, University of Ruhuna, from February to July 2025. Initial pellets contained 2.2% total nitrogen (TN), 10.34% phosphorus, 2.82% potassium, pH 8.4, and electrical conductivity (EC) 6.13 mS/cm. TN, phosphorus, potassium, pH, EC, and ammonia emission were measured every two months. Data were analyzed using ANOVA in SAS software (version 9.1.3), with mean separation by Duncan’s multiple range test at p<0.05. Results showed that a decline in TN was observed in all treatments, with T2 and T3 showing significantly higher values at 2 months (2.15% and 2.18%), while T3 maintained significantly highest TN at 4 and 6 months (2.14% and 2.11%). pH increased in all treatments with significantly higher values in T2 (8.87 and 9.02) and T3 (8.85, 9.07) at 2 and 4 months, while T3 recorded the significantly highest pH (9.40) at 6 months. EC increased over time, with T3 consistently showing the significantly highest values at all sampling intervals (7.59, 8.81, and 10.22 mS/cm). Ammonia emission decreased during storage, with T3 exhibiting the significantly lowest values (5.67, 1.47, and 1.43 mg at 2, 4, and 6 months). These results indicate that high-density polyethylene- 500-gauge (T3) effectively preserves nitrogen, maintains physicochemical stability, and minimizes ammonia volatilization during storage.