Food industrial processing wastes applications in sustainable soil pest management and biogas production Yigal Achmon 1,2,* , Jesús D. Fernández-Bayo1,2 , Katie Hernandez3,4 , Dlinka, G. McCurry3 , Duff R. Harrold2 , Joshua T. Claypool2 , Joey Su1 , Ruth M. Dahlquist-Willard3 , James J. Stapleton5 ,Jean S. VanderGheynst2 , and Christopher W. Simmons1 (1)Department of Food Science and Technology, University of California, One Shields Ave., Davis, CA 95616, United States (2)Department of Biological and Agricultural Engineering, University of California, One Shields Ave., Davis, CA 95616, United States (3)University of California Cooperative Extension, Fresno County, 550 East Shaw Avenue,Suite 210-B, Fresno, CA 93710, United States (4) School of Natural Sciences, Fresno Pacific University, Fresno, CA 93702, United States (5) Statewide Integrated Pest Management Program, University of California, Kearney Agricultural Research and Extension Center, Parlier, CA 93648, United States Introduction Aims To investigate multiple potential sustainable applications for tomato and wine grape processing wastes (tomato and grape pomaces), the following studies were conducted: Laboratory Biosolarization: A bioreactor system that can screen potential soil amendments by simulating soil conditions during biosolarization. Field Biosolarization: Field trials to examine biosolarization pest inactivation efficacy when using pomace amendment. Anaerobic digestion: Batch anaerobic digestion studies to gauge the potential of tomato and wine processing wastes as feedstocks to produce methane. Food, agriculture, and energy are intricately connected. Sustainable agriculture and food processing requires recycling waste streams for beneficial processes such as soil treatment (by means of Biosolarization – an environmental friendly fumigation technique using solar heat and organic amendments) and energy production. Proposal: Utilizing new energy sources that could reduce the use of fossil fuels is important for a sustainable energy future. Renewable organic matter resources such as tomato pomace (TP) from industrial tomato processing can be a feedstock for sustainable energy. Results Lab Biosolarization Field Biosolarization Anaerobic Digestion Figure 1: Bioreactor systems for simulated solarization. Bioreactor conditions represent the anaerobic environment that may be encountered at deeper soil depths where oxygen diffusion is limited and in the aerobic environment that may occur closer to the soil surface due to oxygen diffusion through the tarp and from surrounding uncovered soil. Figure 4: Transverse cutaway of the field plot illustrating two soil microcosms as they would appear when embedded in the soil during biosolarization. The cutaway of the microcosm reveals the arrangement of weed seed packets and temperature loggers within the soil. Figure 6: Micro-Oxymax respiration system having the ability to continually measure CO2, H2 and CH4 generated in anaerobic digestion conditions. First feed Second Feed Third Fourth B A A B Figure 2: Carbon dioxide (CO2) evolution in soil amended with compost and pomace . Cumulative CO2 evolution (cCER) in the aerobic system, Data represent the mean of four replicate bioreactors. Figure 5: Kinetic results of weed seeds mortality (%) (A) mustard seeds and (B) nightshade seeds. Treatments are as follows: Field Soil control – 100% non-amended solarized soil, RT Soil control – 100% non-amended soil at ambient room temperature (RT) conditions, Field 2.5% Tomato Pomace (TP) and 2% Green Waste Compost (GWC) – solarized soil amended with 2.5% TP and 2% GWC, RT 2.5% TP and 2% GWC –soil amended with 2.5% TP and 2% GWC at ambient RT conditions. Values are given as mean±standard deviation (n=5). Figure 7: Results of biogas production in a high solids AD (25% solids dry basis) on tomato and wine grape pomaces from the Micro-Oxymax system (in 250ml bioreactors) at thermophilic conditions (55ºC). (A) Enrichment study by repeated pomace feeding of 1% organic substrate. The systems (n=3) were started as 100 g fresh weight (of which 80% manure and 19-20% compost and 1% pomace). (B) Enrichment with different organic loading rates (1%, 5% and 10% pomace). Figure 3: Soil temperature elevation during simulated biosolarization of soil amended with compost and pomace in the aerobic system. Temperature elevation is relative to control bioreactors lacking pomace amendment. Data represent the mean of four replicate bioreactors. Conclusions Lab Biosolarization: Simulated Biosolarization in bioreactors permits screening of organic residues from various industrial waste streams as soil amendments ahead of resource-intensive field trials. Studies involving abundant California fruit processing residues showed that white wine grape pomace and tomato pomace led to significant soil temperature elevation under aerobic conditions and significant pH decreases under anaerobic soil conditions. These changes induced soil conditions that are consistent with those known to inactivate weed seeds and microbial pathogens. Field Biosolarization: The study showed for the first time in a field trial the weeds suppressing ability that TP amendment combined with soil solarization has. GWC addition was also shown to have an important role in determining the microbial activity in the biosolarized treatments. Anaerobic Digestion: Enriched high solid anaerobic digester with tomato pomace and white wine grape gave promising methane production results. http://simmons.ucdavis.edu/ *(530-4929827) yachmon@ucdavis.edu