A new study published by the Teagasc environment research centre has shown that there was no impact of soil inhibitors (urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) – incorporated into protected urea fertiliser) on the structure and abundance of soil bacterial and fungal communities. The research was conducted over a five-year period and followed repeated application to an intensively managed grassland.
The research, which has been published in the scientific journal, ‘Soil Biology and Biochemistry’, further demonstrated that the microbial communities involved in nitrogen cycling and nutrient transformation processes remained unchanged with the use of the urease inhibitor. Fertiliser application, either via calcium ammonium nitrate (CAN) or urea, did change the fungal community structure, but the bacterial community structure in fertilised plots was not significantly different from the unfertilised plots.
Urease inhibitors such as N-(n-butyl) thiophosphoric triamide (NBPT) block the active site of the urease enzyme thus moderating the speed of urea conversion to ammonium in, or, on soil, resulting in reduced nitrogen losses and greater nitrogen use efficiency. Previously, research from Teagasc Johnstown Castle has demonstrated that switching from CAN to protected urea fertiliser reduced nitrous oxide emission factors by 71% and reduced ammonia volatilisation by 78.5%, while maintaining grass yields.
Teagasc Soil and Plant Nutrition Researcher Patrick Forrestal stated that “the work highlights the value of long-term field trials where the effects of nutrient strategies on soil health, plant performance and environmental loss mitigation can be evaluated to provide solid advice for farmers and the Agri-Food sector.”