Integrating analysis of carbon, nitrogen and water footprint for evaluating crop production sustainability

Ecosystem service could be affected by agricultural activities through carbon, nitrogen and water cycling in soil; however, faultless ecosystem service is indispensable for agricultural sustainable development under global climate change. Carbon, nitrogen and water footprint were developed to quantify the impact of human activities on ecosystem and environment in recent years. In this study, a methodology of carbon, nitrogen and water footprint quantification was developed to evaluate crop production sustainability. Integrating analysis was also employed to quantify the impact of crop production on ecosystem and environment from greenhouse effect, nitrogen loss and water consumption and their relative contributions. Paddy rice production had the highest carbon (1.59 kg CO₂-eq kg^-1) and water footprint (6.04 m³ kg^-1) but the highest nitrogen footprint was found in maize production (10.8 kg Nr kg^-1). Methane emission was the largest contributor of carbon footprint for paddy rice production; however, fertilizer production and irrigation contributed most for carbon footprint of maize and wheat production. Reactive nitrogen leaching accounted for 68% of the total nitrogen footprint for maize production, and ammonia volatilization made the biggest contribution for nitrogen footprint of paddy rice production. Based on the integrating analysis, the aggregated impact point of rice cropping system was higher than that of dry cropping system, of which water loss made the significant contribution.