دانلود رایگان مقاله شناسایی نقاط مهم در انتشار کربن از یک مزرعه گیاه ارگانیک در مقیاس کوچک

abstract

Despite its potential to mitigate many environmental impacts of agriculture, organic farming does contribute to greenhouse gas (GHG) emissions. A full accounting and understanding of the GHG emissions associated with specific activities, materials, and energy used in organic operations are needed to support decision-making for GHG mitigation. A small-scale organic vegetable farm in Washington State, USA, was used as a case study to determine the carbon footprint (CF) and GHG hotspots. A partial life cycle assessment was conducted to identify primary and secondary GHG fluxes associated with activities and materials used in production of potatoes, cauliflower, dry bush beans, winter squash, summer squash, chard, peppers, and onions grown in a crop rotation. The CF associated with each crop ranged from a low of 1.68 t CO2-eq ha−1 yr−1 for chard to a high of 2.67 t CO2-eq ha−1- yr−1 for cauliflower. Cauliflower had the highest CF per ha followed by potatoes and pepper. Across the farm as a whole, the major CF hotspots were fuel use for both on-farm and off-farm operations (38%), fertilization (18%), soil emission (12%), and irrigation (11%). Simulation of a switch to biodiesel instead of petroleum gasoline and diesel resulted in a 32% reduction in the total farm CF. By identifying the CF hotspots of a whole farm and individual crops, particular inputs and activities can be targeted for modification in order to effectively reduce the farm's CF.

4. Summary and conclusions

Effective mitigation by agriculture of GHG emissions and hence global climate change requires identification of significant CF and GHG sources or hotspots in agricultural production systems. Our study of a small organic vegetable farm identified fuel use, organic fertilizer, soil emissions, and irrigation as the major hotspots in the CF. Cauliflower, potato and pepper crops had the highest CF ha−1 among the crops grown in this test case. The use of biodiesel in place of gasoline and diesel combined with the use of solar powered irrigation system in place of grid powered irrigation systems could reduce the CF of the farm by 34%. Specialized plastic materials (i.e., hoop house for pepper and row cover for cauliflower) with high CF might be replaced or their lifespan might be extended to reduce annual CF. This study also established that the absolute values of the CF estimated for various crops may vary, depending on materials and activities included in the chosen system boundaries. Estimation of CF will be useful in identifying hotspots of materials and activities with the largest targets for CF reduction. This will enable farmers, businesses, and policymakers to innovate and focus efforts on finding viable alternatives that provide the greatest benefit to reducing the carbon footprint of agriculture.