Life Support Biosph Sci. 1997 ; 4(3-4): 167-78.

Food production and nutrition for the crew during the first 2-year closure of Biosphere 2.

Silverstone SE.

Biospheres LLC, Bonsall, CA 92003, USA.

Biosphere 2's finite natural resources: atmosphere, plants, water, and soil, and its unique increased rate of nutrient cycling, mandated a design for the agriculture that emphasized sustainability and high productivity. The results of the initial 2-year test of the agriculture system showed that it could provide a diet that was both nutritionally adequate and pleasing to the palate of the eight-member crew from September 1991 to September 1993. The agriculture design was developed from 1985 to 1991 at the Space Biospheres research greenhouses with consulting from the Institute of Ecotechnics (London) from its experiments in New Mexico, Australia, and France and the Environmental Research Laboratory (University of Arizona). During the 2-year mission this research was continued with the close collaboration of outside scientific consultants, particularly in the area of soil management and integrated pest management. The 2000-m2 cropping area provided approximately 81% of the overall nutritional needs of the crew. Initial results showed light to be the main limiting factor and the additional electric light was added after the first 2-year mission to increase the productivity for future experiments. The diet was primarily vegetarian supplemented with daily amounts of milk, and weekly meals of meat and eggs from the system's domestic goats, pigs, and chickens. Nontoxic methods of pest and disease control were used. The main pest problems were broad mite and root knot nematode. Inedible plant material, domestic animal wastes, and human waste water were successfully processed for nutrient return to the soil. Eighty-six varieties of crops were grown in Biosphere 2. Major staple crops included rice, sweet potato, beets, banana, and papaya. The African pygmy goats were the most productive of the domestic animals producing on average 1.14 kg of milk per day. The diet averaged 2200 calories, 73 g of protein, and 32 g of fat per person per day over the 2 years. The crew had a 10-20% weight loss, mostly occurring in the first 6 months of closure, after which weights stabilized with some increase in the second year. Agriculture field management took 25% of crew time, animal care required an additional 9% and food preparation accounted for 12% of crew labor.