Influence of biochar‐based urea substituting urea on rice yield, bacterial community and nitrogen cycling in paddy fields

Abstract

BACKGROUND There is an increasing understanding of the importance of biochar‐based fertilizers in agroecosystems. However, no research has evaluated the effects of partial substitution of urea with biochar‐based urea on rice yields and soil microbial communities. We therefore investigated the rice yields, bacterial communities, and gene abundance involved in nitrogen in silty clay and sandy loam soil paddy fields treated with urea (U), total substitution of urea with biochar‐based urea (BSU), partial substitution of urea with biochar‐based urea in basal and tillering fertilizers (BSU1), and partial substitution of urea with biochar‐based urea in panicle fertilizers (BSU2). RESULTS Compared with U, applying biochar‐based urea increased rice yields, with BSU2 having the most notable effect. Principal coordinate analysis revealed that bacterial communities treated with BSU2 in both soils were significantly different from those treated with U and BSU, most probably due to the decrease in pH caused by the decrease in the concentration of ammonium. The relative abundance of Subdivision3_genera_incertae_sedis, Azotobacter, Geobacter, Buchnera, and Terrimonas in silty clay soils and Saccharibacteria_genera_incertae_sedis and Geobacter in sandy loam soils significantly increased when treated with BSU2 and was positively correlated with rice yields, indicating that the improvements in rice yield were associated with changes in bacterial communities. Based upon amoA/narG related to nitrate accumulation and norB/nosZ related to nitrous oxide emissions, BSU2 enabled a lower risk of nitrate leaching and nitrous oxide emissions in both soils, in comparison with the U and BSU treatments. CONCLUSION The BSU2 treatment had a stronger yield‐increasing effect than biochar‐based urea alone and lowered the risk of nitrogen pollution, which is beneficial to the sustainable development of paddy fields. © 2022 Society of Chemical Industry.

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

“…Incorporating urea fertiliser into aerobic soil prevents N loss due to NH 3 volatilisation (Dominghetti et al 2016). Zhang et al (2022) reported the partial substitution of urea with biochar in panicle initiation has a more substantial yield-increasing effect and lowered the risk of nitrogen pollution in silty clay soils and sandy loam soils in paddy fields.…”