Evaluation of nitrogen concentrations in bioponics under acetic acid additions

Abstract

The bioponic system is a combination between hydroponic vegetable cultivation and organic waste. The system can circulate nitrogen elements from the use of bio-fertilizers. In bioponic systems, there are microorganisms that can convert organic matter into a usable form of plants. Nitrogen transformation in bioponics is critical to the plant efficiency in utilizing nitrogen for growth in bioponic systems and reducing emissions to the environment. In this study, bacterial species linked to nitrogen transformation was studied by analyzing the microbial community groups using Next-Generation Sequencing. 14 plants per system) and 500 grams of chicken manure were used as a food source for plants. The system was added to acetic acid (5% w/v) for Phase I (0 ml acetic vs 700 ml acetic acid) and Phase 2 (350 ml acetic vs. Acetic acid 1050 ml.) Phase 3 (acetic acid 0 ml. 350 ml. 700 ml. and 1,050 ml.) From this study, it was found that adding acetic acid to the bioponic system had negative effect on the plant efficiency of nitrogen utilization and also plant growth. It was found that the system without the addition of acetic acid gave the best plant growth. In addition, the results of the research showed that the bioponic system had good water quality for plants and microorganisms for growth. The water quality parameters were dissolved oxygen, pH, temperature, total ammonia, nitrite, nitrate and plant weight. The values were as follows: 6.6 ± 0.3 mg /L, 7.7 ± 0.1, 29.4 ± 1.8 °C, 3.0 ± 0.6 mgN/L, 2.4 ± 0.7 mgN/L, 2.6 ± 1.0 mgN/L, 921.5 ± 358.5 g (acetic acid concentration 0 ml); 6.7 ± 0.2 mg/L, 6.3 ± 0.7, 28.8 ± 1.3 °C, 2.8 ± 1.0 mgN/L, 2.3 ± 1.3 mgP/L, 3.0 ± 1.4 mgN/L, 545.0 ± 339.4 g (acetic acid concentrate 350 ml); 6.1 ± 0.4 mg/L, 6.1 ± 1.0, 29.5 ± 1.9 °C, 3.1 ± 1.3 mgN/L, 2.5 ± 1.6 mgN/L, 3.0 ± 1.5 mgN/L, 402.5 ± 208.6 g (acetic acid concentration 700 ml); 6.9 ± 0.2 mg/L, 5.0 ± 0.3, 28.7 ± 1.4 °C, 2.6 ± 1.9 mgN/L, 3.9 ± 1.9 mgN/L, 3.0 ± 2.2 mgN/L, 338.0 ± 299.8 g (acetic acid concentration 1050 ml) respectively, which showed that adding acetic acid had a negative effect on nitrogen utilization efficiency. Also, the addition of acid reduced plant growth. In addition, groups of bacteria such as Xanthobacteraceae have been found to influence the nitrogen cycle in the bioponic system. It is responsible for the conversion of nitrogen gas to total ammonia through nitrogen fixation process. Groups of bacteria Lentimicrobium and Rhodobacteraceae converted total ammonia to nitrite with ammonia oxidation process. This study found groups of bacteria Nitrosomonadaceae and Proteobacteria (converting nitrite into nitrate with nitrite oxidation process) and bacterial groups Denitratisoma and Microscillaceae, which are responsible for process that nitrate is converted back to nitrogen gas through denitrification process. Therefore, the study showed that bioponics was effective in the nutrient circulation from organic fertilizers; however, high concentration and loading rate of acetic acid could inhibited plant growth.