Lettuce growth and phosphorus leaching in media amended with phosphorus-treated magnetite

A. Graham, J. H. Gillman, C. J. Rosen

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Magnetite was examined for use as a medium on which to bind phosphorus (P) for the purpose of reducing P leachate from container grown crops. Magnetite was acid washed, pH adjusted to 5.0, and then shaken in a 10,000 mgP·L -1 solution. The P-magnetite was chemically characterized to determine P content (176 mgP·kg-1 magnetite). A greenhouse experiment was performed to determine the accessibility of the P from the P-magnetite to the plant and the amount of P leachate. 'Valmaine' Romaine lettuce Lactuca sativa was sown into 5.5 inch standard containers and treated with one of the following: 250 g P-magnetite (44 mg P), 150g P-magnetite (26mg P), 50g P-magnetite (8.8mg P), 150g untreated magnetite, 3g 15-9-12 Osmocote (119 mg P), 21-5-20 constant liquid feed (5.25 mg P/fert. event), and no treatment. For four weeks, weekly leachate samples were taken and analyzed for P content. At the completion of four weeks, the shoots were dried and weighed. The constant liquid feed treatment had the highest P leachate and shoot dry weights. Osmocote and 150 g P-magnetite had similar P leachate, and the shoot dry weights for the 150 g Pmagnetite treatment were significantly higher than for Osmocote. This study demonstrated that P from amended magnetite is accessible for uptake by plants and leachate was reduced using P-magnetite compared to a constant liquid feed.

Original languageEnglish (US)
Title of host publicationXXVI International Horticultural Congress
Subtitle of host publicationToward Ecologically Sound Fertilization Strategies for Field Vegetable Production
PublisherInternational Society for Horticultural Science
Number of pages5
ISBN (Print)9789066053205
StatePublished - Nov 1 2003

Publication series

NameActa Horticulturae
ISSN (Print)0567-7572


  • Eutrophication
  • Fertilizer
  • Runoff
  • Slow-release


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