# The Evolutionary Traits of Carbon Emissions from the Planting Industry in Beijing, China
## 3 Results
### Carbon Emissions from the Planting Industry
#### Carbon Emissions of N\({}_{2}\)O from Agricultural Land  
Direct carbon emissions of N\({}_{2}\)O come from nitrogenous fertilizers, organic fertilizers, and straw returning to fields. From the results (Figure 3), it can be seen that the carbon emissions of the three pathways all show a downward trend. The carbon emissions of N\({}_{2}\)O caused by nitrogen-containing fertilizers, organic fertilizers, and straw returning to fields  
Figure 2: Level of carbon emissions from agricultural inputs in Beijing’s planting industry from 2000 to 2023.  
dropped from 206,100, 38,400, and 29,100 tons in 2000 to 52,700, 7500, and 10,200 tons in 2023, respectively, which were only 25.56%, 19.57%, and 35.16% of the initial value. The total direct carbon emissions of N\({}_{2}\)O from farmland dropped from 273,600 tons in 2000 to 70,400 tons in 2023, which was only about one-fourth of the initial value. Overall, the carbon emissions of the three pathways accounted for 73.64%, 15.89%, and 10.46% of the direct carbon emissions of N\({}_{2}\)O from agricultural land.  
The indirect carbon emissions of N\({}_{2}\)O from farmland include two parts: the carbon emissions from atmospheric ammonia deposition and the carbon emissions from soil nitrogen leaching and runoff. The results show that the indirect carbon emissions of N\({}_{2}\)O are mainly from atmospheric ammonia deposition, accounting for 66.48% of the total indirect carbon emissions (Figure 4). Overall, the carbon emissions from atmospheric ammonia deposition, soil nitrogen leaching, and runoff also showed a downward trend. They decreased from 92,500 and 46,800 tons in 2000 to 22,700 and 12,000 tons in 2023, respectively, dropping by 75.44% and 74.26%, which was only about one-fourth of the initial value.  
Figure 4: Indirect carbon emissions of nitrous oxide (N\({}_{2}\)O) from farmland in Beijing in 2000–2023.  
Figure 3: Direct carbon emissions of nitrous oxide (N\({}_{2}\)O) from farmland in Beijing in 2000–2023.  
Total Carbon Emissions of N\({}_{2}\)O from Agricultural Land  
The results show that the carbon emissions of N\({}_{2}\)O from farmland in 2000 are 412,900 tons, of which direct carbon emissions are 273,600 tons and indirect carbon emissions are 139,300 tons (Figure 5). The carbon emissions of N\({}_{2}\)O from farmland in 2010 were 296,500 tons, a decrease of 28.19% compared to 2000, with direct and indirect carbon emissions decreasing by 27.92% and 28.72%, respectively. The carbon emissions of N\({}_{2}\)O from farmland in 2023 were 105,200 tons, of which direct carbon emissions were 70,423 tons and indirect carbon emissions were 34,769 tons, and a further decrease of 64.53% compared to 2010. The average level of direct carbon emissions of N\({}_{2}\)O from farmland caused by chemical fertilizers, organic fertilizers, and straw returning to fields was 66.21%, while the level of indirect carbon emissions of N\({}_{2}\)O caused by atmospheric ammonia deposition, soil nitrogen leaching, and runoff was 33.79%. Therefore, direct carbon emissions were the most important part of N\({}_{2}\)O carbon emissions from farmland in Beijing, with a ratio of nearly 2:1, and there was no significant change in the amount during the period from 2000 to 2023.