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A slow release brown coal-urea fertiliser reduced gaseous N loss from soil and increased silver beet yield and N uptake

Saha, Biplob K., Rose, Michael T., Wong, Vanessa N.L., Cavagnaro, Timothy R., Patti, Antonio F.
The Science of the total environment 2019 v.649 pp. 793-800
Beta vulgaris, ammonia, beets, biomass production, coal, crop yield, ecological footprint, greenhouse gas emissions, losses from soil, nitrogen content, nitrogen fertilizers, nitrous oxide, nutrient use efficiency, organic carbon, soil types, urea
Increasing crop yield and fertiliser nitrogen (N)-use efficiency is important for productive agricultural systems with a reduced environmental footprint. The aim of this study was to assess the effect of slow release brown coal-urea (BCU) fertiliser on the gaseous N losses, biomass yield and N uptake by silver beet (Beta vulgaris L.) compared to commercial urea. Two soils were amended with urea, BCU 1 (22% N) or BCU 2 (17% N) as N-fertiliser at the rate of 50 or 100 kg N ha−1. Five gas sampling periods were undertaken to measure the loss of N as N2O and NH3. After 10 weeks, biomass, N concentration, and N uptake of silver beet, and mineral and mineralisable N of post-harvest soil were measured. BCU substantially increased fertiliser N availability and uptake by silver beet, reduced N2O emission by 29% and NH3 emission by 36% compared to urea alone, irrespective of soil type. Compared to urea, BCU blends increased biomass yield by 27% and 23% in a Tenosol and Dermosol soil, respectively. In addition, application of BCU fertiliser substantially enhanced the potentially mineralisable N and organic carbon content of soil. These results provide evidence that granulation of urea with brown coal (BC) can increase silver beet N-use efficiency and yield in different soil types, and more work is now required to validate this technology for other crops.