Greenhouse gas flux from green waste compost windrows and following application to soils in almonds and tomatoes

Transcription

1 Greenhouse gas flux from green waste compost windrows and following application to soils in almonds and tomatoes William R. Horwath Dept. Land, Air and Water Resources, Univ. California, Davis, CA, USA BioCycle 27 th Annual West Coast Conference 2013 April 8,9,10,and 11 San Diego, California

2 Why is compost important? Landfills are the third largest source of methane emissions in the U.S., accounting for nearly 20% of total methane emissions 1 California dumps 35 million tons of waste per year into landfills 2 30% is compostable organic material

3 Background Why measure GHG Flux? Composting is a source of GHG emissions; CH 4 and N 2 O Methane and N 2 O have a higher greenhouse effect than CO 2 California Global Warming Solutions Act of 2006 mandates a decrease in GHG emissions by 2020 Composting has been increasing in use as a waste diversion from landfills but the emissions from composting are not well characterized

4 What Is Composting? Managed decomposition Feedstocks: Yard-waste Agricultural residues Food-waste Manure Uses: Soil Amendment Organic Fertilizer

5 Objective Determine the GHG Emissions of Windrow Composting Measure the greenhouse gas (GHG) flux of: Methane Nitrous oxide Characterize the windrow by measuring: Temperature Moisture content Internal concentration of O 2 C/N ratio NO 3 - and NH 4 + extraction concentrations Measure GHG in almond and tomato following compost application

6 Background Windrows Feedstock for the Green Compost: Green waste (grass, leaves and trimmings) from Davis, Woodland, etc. Green waste and food scraps Food waste is only 5-15% of the compost feedstock Shredded and laid in windrow formations Mechanically turned

7 Method-Chamber Sampling Monitor the compost over its maturation (9-12 weeks) Turning occurs at least 5 times in the first 15 days then approximately once per week. When possible take measurements before and after the turns 10 meters

8 Method- Sweep Flux Chamber Sampling Nitrogen Sweep gas E = Q sweep Y sample /A Andersen, J. and Boldrin, A. 2010

9 Method-Micrometeorological Sampling Four sampling towers with four sampling lines at different heights (16 total sampling points) Uses a real time, photoacoustic gas analyzer Eric Kent, 2012

10 $"# $"# &"# %"#!"#!"# %"# &"#

11 Results Pile Chamber comparison Pile 1-05/22/ Days Summer sampling Warm weather Added water to keep pile moist Regular turning events except for one week Pile 2-11/05/ Days Fall Sampling Many rain events Rain kept the pile saturated Turning events delayed by weather (less oxygenation) Lower internal temperatures than Pile 1

12 Results Pile 1, 05/22/2012 Daily Flux vs. Windrow pile age CO 2 +CH 4 : (g/m 2 /day), N 2 O: (mg/m 2 /day) '( )#

13 Results Pile 2, 11/05/2012 Daily Flux vs. Windrow pile age CO 2 +CH 4 : (g/m 2 /day), N 2 O: (mg/m 2 /day)

14 Results Pile Chamber Comparison- Flux Integration Integrated Flux Average Flux per Day Pile 1-05/22/2012 (58 Days) Pile 2-11/05/2012 (44 Days) Pile 1-05/22/2012 (58 Days) Pile 2-11/05/2012 (44 Days) CH 4 1,180 ± 113 g/m 2 8,899 ± 1,320 g/m 2 20 ± 2 g/m 2 /day 202 ± 30 g/m 2 /day CO 2 330,891 ± g/m 2 404,148 ± g/m ±389 g/m 2 /day 9185 ± 265 g/m 2 /day N 2 O 36,109 ± 5,556 mg/m 2 6,782 ± 483 mg/ m ± 96 mg/m 2 /day 154 ± 11 mg/m 2 /day

15 Conclusions- Pile Chamber Comparison There are significant differences between the emissions of the two studied piles N 2 O emissions are higher in the Pile 1 Higher temperatures and more frequent oxygenation CH 4 emissions are higher in Pile 2 Lower temperatures and less oxygenation Between seasons there are many factors that can could be contributing to the variability in the data Feedstock, temperature, weather events, etc.

16 Results- Micrometeorological Comparison A: 6/1-6/4 B: 6/5-6/14 C: 6/15-6/21 D: 6/22-6/27 E: 6/28-7/7

17 Results- Micrometeorological Comparison CH 4 flux [mg m -2 s -1 ] NO 2 flux [µg m -2 s -1 ] CO 2 flux [mg m -2 s -1 ] Dates Chamber Micromet Chamber Micromet Chamber Micromet A: 6/1-6/ B: 6/5-6/ C: 6/15-6/ D: 6/22-6/ E: 6/28-7/ All

18 Greenhouse Gas Emissions of Compost Amended Almond Orchards

19 Objectives Measure greenhouse gas emissions using a closed chamber approach to determine the effect of using compost to amend almond orchard soil. Monitor this orchard over 2 years with one application of compost in the fall. Repeat a second year on different plots.

20 Experimental Design Four Treatments with Three Replications Control - Almond Plot with no applied compost Single Rate - Almond Plot with a Single rate of compost used by Almond growers (3 Tons Dry Compost Per Acre) Double Rate - Almond Plot with Double the rate of compost used by Almond growers (6 Tons Dry Compost Per Acre) Road - Non-irrigated road area between almond rows with no applied compost Compost is applied on top of the soil only.

21 Treatments Control - No Compost Single rate Compost Double rate Compost Road - No Compost Dimensions of Plot Area 16ft 4ft

22 A) Control B) Single Rate C) Double D) Road

23 Results Monitored from 11/1/2011-9/14/2012 (318 Days)

24 Greenhouse gas emissions of compost amended tomato production fields

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28 Conclusions The micrometeorological method gives similar results on the same order of magnitude as the flux chamber approach Compost application in almond show significant reductions of N 2 O emissions Compost application in tomatoes shows no significant effect on N 2 O emission

29 Future Research Monitor more windrow for seasonal response Use the Flux Chamber and Micrometeorological method in parallel Pile 3 - Winter/Spring sampling current Compare the results of the two methods Monitor one more season in almonds

30 Acknowledgements! Shannon Bailey! Eric Kent! Kyaw Tha Paw U! Martin Burger CalRecycle grant IWM09027 and J.G. Boswell Endowed Chair in Soil Science.