Author(s): A B Lloyd, M Jane Sheaffe
Bacteria which can hydrolyse urea are common in soils. Of six soils examined, some 17–30 per cent of the total bacterial populations, including aerobes, micro-aerophiles and anaerobes, could hydrolyse urea. One of the soils had been enriched with urea for at least ten years, yet the proportion of ureolytic bacteria (24 per cent) was similar to that of normal soils. Addition of urea to a red-yellow podzolic soil low in available carbon and under different moisture conditions did not increase the total urease activity, the size of the bacterial population or the ratio of ureolytic to non-ureolytic bacteria. However, when available carbon as glucose was added with urea to this soil, urease activity and size of the bacterial population both increased, but the ratio of ureolytic to non-ureolytic bacteria in the population remained unchanged.