Nitrogen losses (N2O and NO3–) from mustard (Brassica juncea L.) cropping applied urea coated bio-charcoal

Abstract

Most farmers use urea as a nitrogen fertiliser to raise mustard (Brassica juncea L.), although its nitrogen (N) content is quickly lost due to its hygroscopic nature. Nitrogen loss in the form of nitrous oxide (N2 O) and nitrates (NO3–) has been causing low nitrogen fertiliser efficiency in vegetable cultivation. This investigation aims to assess the impact of urea fertiliser coated with biochar or activated charcoal on losses of N2 O and NO3– concentration in the soil during mustard production. The experiment used a randomised block design with five treatments of urea fertiliser coated with biochar/activated charcoal. The observed data included N2 O flux, nitrate, and ammonia content in soil and water. The results showed that urea fertiliser coated with activated charcoal from corn cobs tended to suppress N loss more effectively than urea coated with biochar or activated charcoal from coconut shells. Biochar and activated charcoal from coconut shells suppressed N-N2 O loss as much as 3.1% and 52.5% (7 days after planting (DAP)), respectively, and 68.7% and 71.6% (21 DAP), respectively. Biochar and activated charcoal from corn cob reduce N-N2 O loss by 46.5% and 66.5% (7 DAP), respectively, and by 70.7% and 77.8% (21 DAP). Urea-coated activated charcoal fertiliser increases mustard plant biomass and nitrogen uptake. Biochar and activated charcoal from coconut shells and corncobs increase nitrogen use efficiency by 5, 24, 6, and 17%, respectively. Biochar/activated charcoal coatings are a promising technology for boosting nitrogen use efficiency in vegetable crops, including mustard crops.