Environmental trade-offs and productivity gains through sustainable nitrogen use in an intensive high-input sugarcane production system in China

High nitrogen (N) fertiliser input in Chinese sugarcane production has substantially increased the risk of reactive N (Nr) loss and crop productivity improvement for a long time. However, there is no comprehensive study of sustainable N management on different N loss pathways in a high N input cropping system of China. Here, a field experiment with 5 treatments (control (CK); conventional urea (OPT; 300 kg N ha −1 ); partial substitution of urea with coated urea (OPT-CU; 300 kg N ha −1 ); nitrification inhibitor (3,4-dimethylpyrazole phosphate, DMPP)-blended urea (OPT-NI; 300 kg N ha −1 ); and partial substitution of urea with organic N fertilizer (OPT-ON; 300 kg ha −1 )) was conducted in a commercial sugarcane farm for two cropping years to understand how different N management strategies attenuate Nr losses (emission of ammonia and nitrous oxide (N 2 O), and N leaching) of sugarcane crops. The results showed that OPT-CU has increased sugarcane yield by 2.5 %-9.5 % and decreased ammonia and N 2 O emission by about 33.9 % and 44.4 %, respectively, compared with OPT treatment. Coated urea application however increased N leaching loss by 29.5 % (174 kg ha −1 ) relative to OPT (136 kg ha −1 ). OPT-NI treatment decreased N 2 O emission by 53.0 % but increased ammonia volatilization as much as 52 %, compared with OPT treatment. Though the N leaching loss was similar to other treatments, cane yield of OPT-NI crops was 3.03–5.18 % lower than that OPT treatment. More significantly, in this study OPT-ON was found to reduce both ammonia and N 2 O emission by about 42.7 % and 32.5 %, respectively, but again N leaching loss (139 kg ha −1 ) and cane yield were comparable to OPT treatment. Taken together, our study concludes that partial substitution of synthetic N with organic N fertiliser could yield both economic and environmental benefits maximally, making sugarcane a more sustainable food and energy crop. • Partial substitution of urea with coated urea or organic fertilisermakes sugarcane more sustainable. • High sugarcane yield was obtained with all N management strategies tested for two cropping years. • Bulk of the input N was lost as nitrate through leaching under all N management strategies tested. • Partial substitution of mineral N with organic N was the most sustainable N management strategy.