Soil mineralization as effects of plant growth promoting bacteria isolated from microalgae in wastewater and rice straw application in a long-term paddy rice in Central Viet Nam

• Published in: Environmental technology & innovation 2021-11, Vol.24, p.101982, Article 101982
• Main Authors: Toan, Nguyen-Sy, Nguyen, Thi Dong Phuong, Thu, Tran Thi Ngoc, Lim, Duong Thi, Dong, Pham Duy, Gia, Nguyen Thanh, Khoo, Kuan Shiong, Chew, Kit Wayne, Show, Pau Loke
• Format: Article
• Language: English
• Subjects: Anaerobic incubation; Bacillus subtilis; N-mineralization; Paddy soil; Soil carbohydrate; Soil organic carbon
• ISSN: 2352-1864; 2352-1864
• DOI: 10.1016/j.eti.2021.101982

This study investigates the effects of rice straw and potential nitrogen fixing Bacillus subtilis (Bacillus sp.) isolated from seafood wastewater on carbohydrate- and nitrogen mineralization from a long-term rice paddy soil by four weeks anaerobic incubation. Soil collected at the depth of 0–15 cm from a long-term rice paddy cultivation, and set up as following: (1) Control (10 g air dry soil), (2) Rice straw (control ＋ 0.2% rice straw w/v), (3) Bacillus sp., and (4) Combine (rice straw 0.2% w/v and Bacillus sp.) was subjected to an incubator in dark at room temperature/ submerge condition for 4 weeks anaerobic incubation. As showed in results, content of decomposed carbohydrate ranged from 83–447 mg kg −1 soil. Content of extracted carbohydrate was not affected by rice straw application, but significant decreased with bacillus or rice straw-bacillus combine inoculation (2.0–2.2 times decreased) compared to Control treatment, which is closely to the initial soil extraction carbohydrate. In contrary, mineralization nitrogen increased 120% in Bacillus sp. inoculation compared to Control treatment, but Rice straw and Combine treatments resulted in immobilization more than nitrogen mineralization. Inoculation of Bacillus subtilis is recommended as a good environment friendly method to enhance the soil fertility and reduce nitrogen immobilization. Further research within rice plant is therefore needed to consolidate the preliminary results. [Display omitted] •Plant growth-promoting bacterial as green technology in agricultural industries.•Content of decomposed carbohydrate ranged from 83 to 447 mg kg−1 soil.•Bacillus sp., inoculation tended to enhanced soil mineralized nitrogen by 225%.•Sustainable approach to enhance soil fertility and reduce N2 immobilization.