Green route for ammonium nitrate synthesis: fertilizer for plant growth enhancement

Soil fertility management is of great importance for farmers. The use of synthetic nitrogen (N)-fertilizer increased by 20 fold in the last 50 years to feed the increasingly hungry population. This study aims to enrich the plant soil with nitrogen content (NH4NO3 fertilizer in soil) using the low-temperature and low-pressure plasma [without H2 and catalyst]. Subsequently, we used plasma N-enriched soil for plant (radish and tomato) growth. We investigated the germination percentage, seedling growth, seedling weight, phytohormones and antioxidant activity of radish and tomato plants after treatment with plasma N-enriched soil and compared with control soil and soil + commercial N-fertilizer. The plasma N-enriched soil treatment results in significant growth enhancement for both radish and tomato plants. Further, substantial changes in phytohormone and antioxidant levels were observed for the plants grown in plasma N-enriched soil compared to control soil and soil + commercial N-fertilizer. The energy consumption (EC) for total N-fixation was 12 MJ mol−1. EC for ammonia and nitrate fixation was 17 and 41 MJ mol−1, respectively, without H2 gas. Further to understand the plasma chemistry, we performed 1D simulation using COMSOL Multiphysics® software. This study showed that direct N-fixation in the soil by plasma could be used as fertilizer for the plants and open a new window for future decentralized N-fertilizer production at the farm site.