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OBJECTIVESThe participants want to see if a large berm of hot compost in the north side of agreenhouse will provide enough heat to grow standard cool-season crops likesalad greens and brassicas.

ABSTRACTMembers of the Cold Springs Conservancy, a nonprofit educational land trust ofabout 4 acres, want to research CO2 levels, soil and air temperatures and plantproduction and mortality rates of the compost-heated greenhouse during the coldseason mid November to mid April. They will also evaluate the incidence ofdamping-off disease.

The plan is go design a model that can be used by producers in the PacificNorthwest and other areas that dont receive enough sunlight in the winter toeffectively heat a greenhouse. The process will include solar-citing educationfrom the technical advisor, Greg Acker, and the building of two greenhouses,each 80 feet long, 20 feet wide and 15 feet high.

Participants will build and turn the compost pile manure and vegetable waste starting in early October and plant out various salad greens by late October.Theyll monitor temperature daily and ventilate if needed. Each week, ammoniaand carbon readings will be taken along with compost pile heat levels. Weeklycompost samples will be sent to a soil lab for analysis. By late November, if thetemperature in the compost pile drops, the pile will be freshened by adding moremanure, urine and water.

SPECIFIC RESULTSThe results of the study, skewed by several unexpected events, have been

sufficient to suggest some validity in establishing a compost pile inside agreenhouse, perhaps underneath benches or underneath a layer of soil withtomatoes growing on top.

Originally planned for two years with a greenhouse built from scratch, the project was altered to save time.The prefabricated greenhouse ordered showed up late, and when it was finally constructed and the experimentbegun a wind gust tore off the plastic. In the short time it was sealed, however, the compost activelydecomposed and plant growth was luxurious. It is unknown whether the enhanced growth inside thegreenhouse was from the compost heat and carbon or simply the effect of the hoop house.

The greenhouse worked in the second year, but the anticipated compost material manure from a dairy wasnt delivered until November, too late for a proper test of the composting technique.

Still, project coordinator Rebecca Thistlethwaite says some valuable lessons emerged from the failures:

1. Timeliness and preparation of the compost is essential.2. Plant transplants, not seeds, in the hoop houses.3. Salad greens work best in the hoop-house environment.4. Hoop houses help keep out rabbits and ground squirrels, which, in this area, devour most growing

produce.5. On the other hand, the structure harbored thriving winter populations of squash bugs that attacked

early-planted zucchini.

http://wsare.usu.edu

PROJECT REPORTh FARMER/RANCHER h S

Location:Underwood, Washington

Funding Period:Sept. 1999 to Dec. 2000

Grant Award:$1,750

Project Coordinator:Rebecca Thistlethwaite

Cold Springs ConservancyUnderwood, WA 98651

(509) 538-2284th12@hotmail.com

Technical Advisor:Greg Acker, Architect

P.O. Box 31067Portland, OR 97231

(509) 735-9192acker@spiretech.com

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Thistlethwaite observes that the compost pile did give off considerable heat. For the short time the plasticremained on the hoop houses the first year, a tropical atmosphere was created inside. In the second year,tomatoes and basil were planted two months earlier in the hoop house than in the outdoor planting in lateFebruary. Despite slow growth inside the hoop house, the plants did grow and were harvested a month earlierthan the outdoor planting. Also in the second year, a foot-deep layer of finished compost was spread inside thegreenhouse, and the plants, says Thistlethwaite, responded beautifully. The soil was workable and the weedseasy to pull.

POTENTIAL BENEFITSThe project indicates that the heat generated by the compost process could help provide heat for early vegetablegrowth in a greenhouse.

FARMER ADOPTION AND DIRECT IMPACTThere have been no reports that others have tried to replicate this project.

FUTURE RECOMMENDATIONS OR NEW HYPOTHESESThistlethwaite suggests that further research on the subject is needed, especially on the effects of the carbon andnitrogen gases that are released from the decomposing organic matter in the compost pile.

DISSEMINATION OF FINDINGSThe findings have mainly been disseminated through the SARE reports.