Dr Biplob Saha¹, Dr Michael T.  Rose², Dr Vanessa Wong³, Dr Timothy R.  Cavagnaro⁴, Dr Antonio F. Patti¹

¹School of Chemistry, Monash University, Clayton, Australia, ²NSW Department of Primary Industries, Wollongbar Primary Industries Institute, Wollongbar, NSW 2477, Australia, Wollongbar, Australia, ³School of Earth, Atmosphere & Environment, Monash University, Clayton, Australia, ⁴School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, Australia

Improving the soil organic matter content is becoming more important due to its positive effect on soil health, crop growth and nutrient dynamics in agro-ecosystems. Integrated application of organic and inorganic fertilisers has been shown to increase the soil organic carbon (C) and use efficiency of nitrogen (N) fertiliser. Addition of C rich brown coal (BC) as an organic amendment can alter N cycling by reducing its losses in different ways as well as may help to imrove soil organic matter content. However, the effect of brown coal-urea (BCU) granulation on N cycling and soil organic C accumulation is poorly understood. Therefore, a series of glasshouse and field trial studies were conducted to assess the effects of BCU granulation on the dynamics, use efficiency of N and its influence on the organic matter content of soil. Granulation of urea with BC showed a promising impact on the behavior of N fertiliser in the soil system. Compared to urea, BCU granules generally suppressed total N2O and NH3 emissions by 31% and 43%, respectively. Incorporation of BCU granules in soil maintained significantly higher amounts of mineralisable N in soil compared to urea application only. This is supported by the leachate analysis data, which showed that less mineral N was leached from soil in the BCU blends compared to urea. The granules with higher BC had lower N2O and NH3 emissions and maintained higher mineral N in soil compared to the granules with lower BC. Moreover, addition of BCU granules significantly increased the organic C content of the top soil compared to urea alone. The overall results suggest that granulation of urea with BC can strongly reduce N losses and increases the fertiliser N use efficiency. The increase of soil organic C due to addition of BC might be helpful to build up soil organic matter content in the long run.

Keywords: Brown coal-urea granule, soil organic C, dynamics and mineralisation of N, fertiliser N use efficiency, soil health.

Biography: Dr. Biplob Kumar Saha is a Soil Scientist focusing on improving soil organic matter and nitrogen use efficiency through organic and inorganic fertiliser granulation. His main activities are to improve soil health through organic carbon sequestration, reduction of greenhouse gas emissions and monitoring microbial activity and community structure in soil.