Decomposition abilities and characteristics of pig manure using three insect larvae

Abstract

This study investigated the effects of three insect larvae on decomposition abilities and survival rates in Experiment 1 or on pH, total nitrogen, total carbon, and C/N ratio in Experiment 2. A total of hatched 7,500 Tenebrio molitor (TM) larvae, hatched 501 Protaetia brevitarsis seulensis (PBS) larvae, and hatched 15,000 Ptecticus tenebrifer (PT) larvae were randomly subjected to three treatments with three replicates. The treatments were as follows: (1) TM, 5,000 g pig manure + 250 g TM larvae; (2) PBS, 5,000 g pig manure + 250 g PBS larvae; and (3) PT, 5,000 g pig manure + 250 g PT larvae. In Experiment 1, there were significant differences (p < 0.05) in the decomposition abilities of the pig manure from the three insect larvae‐treated groups for 15–30 days. No significant differences in survival rates were observed for any of the in all treatments over time. Decomposition ability and survival rates in pig manure were higher in the PT larvae group than in the PBS and PT larvae groups. In Experiment 2, three insect larvae‐treated pig manure treatments had an effect on total nitrogen for 20 and 30 days, total carbon for 10 and 30 days, and C/N ratio for 20 and 30 days. Thus, our results suggest that the three insect larvae have the ability to decompose pig manure to increase for increasing survival rates or might represent a valuable alternative as organic fertilizer, which could increase the total nitrogen content and decrease C/N ratio.

Evaluation of the decomposition ability and characteristics of pig manure treated with different larval instar stages of black soldier fly (Hermetia illucens L.)

“…Group 1 and 3 C:N ratios ranged from 15.39 to 12.05 over time. This is consistent with the findings of a study on the TC content and C:N ratio in PT‐treated pig manure, which reported values of 41.63% and 13.09 for TC content and C:N ratio, respectively, for Day 30 (Choi 2022). Typically, considerable losses of carbon and nitrogen are unavoidable during composting, resulting in a reduction in compost quality (Zhang et al 2021).…”

“…Other possible factors contributing to the decomposition ability of the BSF larvae could be considered such as nutrient composition of the substrates and larval density, although these were not determined in our experiments since they were out of the scope of the present study. The decomposition abilities results obtained in this study were similar to those reported by Choi (2022), who noted that the decomposition efficiency of pig manure was higher in the Ptecticus tenebrifer larval group than in the other groups. Similar trends were reported by Mahmood et al (2021).…”

“…Similarly to that in Group 1, the TN content in Group 3 did not change significantly. This may be explained by differences in the decomposition abilities of different BSF larval instar stages, concerning microbiological degradation of pig manure (Choi 2022). The TN values of BSF larvae‐treated manure obtained in this study were hardly comparable to those reported in other published studies using chicken, pig, or cattle manure, owing to the different insect larvae or experimental conditions used (Parodi et al 2021; Choi 2022; Grassauer et al 2023).…”

“…1). During the 30-day-long experiment, each BSF larva group was reared in a container (34 × 25 × 25 cm) with aeration holes on the top and fed daily with pig manure, under controlled conditions at 25 ± 2°C with 40 ± 2% humidity and a photoperiod at 16: 8 h light: dark (L:D), as described by Choi (2022). To evaluate decomposition ability of BSF larvae, each plastic box containing pig manure and each BSF larva group was weighed every 5 days.…”

“…This may be explained by differences in the decomposition abilities of different BSF larval instar stages, concerning microbiological degradation of pig manure (Choi 2022). The TN values of BSF larvae-treated manure obtained in this study were hardly comparable to those reported in other published studies using chicken, pig, or cattle manure, owing to the different insect larvae or experimental conditions used (Parodi et al 2021;Choi 2022;Grassauer et al 2023). For the TC content and C:N ratio, significant differences between groups were observed for Days 10 and 25 (p < 0.05) but not for Days 0, 5, 15, 20, and 30 (p > 0.05).…”