Rice paddy microbiology and grain mineral nutrition

Arsenic concentrations were highest in Vietnam and Southern Europe, whereas Sri Lanka showed elevated cadmium. Sulfur-oxidising bacteria, sulfate-reducing bacteria, and methanogenic archaea correlated positively with grain arsenic, while fungi and aerobic bacteria were associated with grain cadmium.</div><div><br></div><div>Chapters 4 and 5 address severe topsoil removal in Bangladesh, where soil erosion and brick production expose nutrient-poor subsoils prone to arsenic contamination.

Pot and multi-site field studies across Boro and Aman seasons evaluated quick compost, rice husk ash, green manure, and soil test-based fertilisers (STBF). Integrated STBF–organic treatments improved soil fertility, shifted microbial communities, and increased groups associated with nutrient cycling and arsenic methylation. These treatments reduced inorganic arsenic in porewater and grains, especially in Boro because of redox-driven microbial changes.</div><div><br></div><div>In conclusion, this thesis provides insights into microbial and geochemical controls over arsenic and cadmium contamination in rice paddies and informs targeted agricultural management practices to reduce contamination risks globally.</div><br><i>Thesis is embargoed until 31 July 2028.</i>