Composted manure turned a Beijing maize field into a climate helper — it now absorbs more warming than it creates

On a clay-loam field in Beijing's Fangshan District, the same fertiliser treatments have run since 2007 — long enough to see what really adds up. In a two-season study published in Frontiers in Microbiology, plots fed only composted poultry manure came out best: their net warming balance averaged negative 11.75 tonnes of carbon-dioxide equivalent per hectare, meaning the soil stored more carbon than the crop season's emissions created. Ordinary urea fertiliser, by contrast, averaged a positive 2.91 tonnes. Manure plots held 16.7–46.2% more carbon in their topsoil, released roughly a quarter less nitrous oxide — a potent greenhouse gas — in 2022, and grew just as much maize. It is one field and two measured seasons, not a universal recipe — but it is measured proof that an old-fashioned practice can pull a working farm's climate balance below zero.

SDG 13 · Climate action