Table 3 Net return to N, N fertilizer costs, global warming potential (GWP) costs and net ecosystem economic budget (NEEB) of N1, N2 and N3 treatments related to N0 treatment.

From: Crop production kept stable and sustainable with the decrease of nitrogen rate in North China Plain: An economic and environmental assessment over 8 years

Treatment

Net return to N

N fertilizer costs

GWP costs

NEEB

 

------------------------------------------------------ $ ha−1 yr−1 ------------------------------------------------------

N1

1218 b

172

31 b

1015 c

N2

1885 a

247

19 b

1619 a

N3

1914 a

348

199 a

1367 b

  1. Nitrogen rates in wheat and maize, respectively, are; 0 and 0 kg N ha−1 (N0), 168 and 129 N ha−1 (N1), 240 and 185 kg N ha−1 (N2), and 300 and 300 kg N ha−1 (N3) in 2009–2016. The results represent the differences between N treatments (N1, N2 and N3) and N0. The price of urea, maize grain and wheat grain are 0.58 $ kg−1 N, 0.29 $ kg−1 and 0.29 $ kg−1, respectively. Net return to N is the increase in grain yield with N multiplied by the price of grain. N fertilizer costs is the nitrogen rate multiplied by the price of urea. GWP costs are calculated based on carbon-trade prices, 17 $ t−1 CO2-equivalent. NEEB = Net return to N - fertilizer costs – GWP costs. Values followed by a different small letter within column are significantly different at P ≤ 0.05.
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