title: [Development of a special controlled-releasing long effect fertilizer used in controlled ecological life support system].
abstract: OBJECTIVE
  To develop a special controlled-releasing long effect fertilizer (SCRLEF) for growing higher plant in controlled ecological life support system (CELSS).
  
  
  METHODS
  First, a plan was designed. According to requirements, some original fertilizers were chosen and compounded in proper proportions, and a granule product was obtained and encapsulated in certain materials to form SCRLEF. Then, experiments were done by measuring the content and releasing-rate of the fertilizer, and cultivating plants with the fertilizer.
  
  
  RESULTS
  The fertilizer contains nutrients for plant growing, such as: N 18.0%, P2O5 14.3%, K2O 12.6%, Ca 2.6%, S 3.5%, Mg 0.12%, and other micro-nutrients. The granules of the SCRLEF are uniform in size with diameters form 2.5 mm to 4.0 mm. Under 20-25 degrees C, the cumulative amounts of released nutrients from the fertilizer in 10 d, 20 d, 30 d, 40 d, and 50 d, are 7.9%, 21.6%, 40.5%, 50.2%, 60.9% respectively, within 10 d, 20 d, 30 d, 40 d, 50 d. By cultivating lettuce with the fertilizer, we found that the vegetable could grow normally, and there wasn't any deficiency symptom in the plants within 45 d.
  
  
  CONCLUSIONS
  The design consideration of the SCRLEF is reasonable. The fertilizer provides total nutrients for plant growing, and can be used to supply the required nutrients for the plants grown in the CELSS.
authors.affiliation: Institute of Space Medico-Engineering, Beijing, China. aiweidang@126.com
authors.forename: Wei-dang
authors.initials: WD
authors.lastname: Ai
authors.forename: Shuang-sheng
authors.initials: SS
authors.lastname: Guo
authors.forename: Jian
authors.initials: J
authors.lastname: Xiao
authors.forename: Lan
authors.initials: L
authors.lastname: Fu
mesh_terms: D003470:Culture Media / Q000494:pharmacology; D018504:Ecological Systems, Closed; D005308:Fertilizers / Q000032:analysis*; D018545:Lactuca / Q000187:drug effects / Q000254:growth & development*; D008021:Life Support Systems; D008903:Minerals / Q000032:analysis; D013026:Space Flight / Q000295:instrumentation; D014893:Weightlessness
chemical_list: D003470:Culture Media; D005308:Fertilizers; D008903:Minerals