The influence of plant age and nitrogen rate on nutrient removal from the container medium solution

TR Number



Journal Title

Journal ISSN

Volume Title


Virginia Polytechnic Institute and State University


Adequate nutrient supply to the medium solution of container-grown crops is a major concern to container plant production practices. The extent to which nutrients are removed by the plant from the medium solution of a container, however, has never been demonstrated. Mariogold, Tagetes erecta ‘Inca’ seeds were glasshouse-grown in 500 cc plastic pots containing 1 peat: 1 perlite (v/v) medium and fertilized daily with 200 ppm N as ammonium nitrate. Thirty, 35, 40, 45 and 50 day old plants were subjected to either 20, SO, 80 or 110 ppm N. Medium solutions were tested at hour 0 and 6, and analyzed for N, P and K. Nitrogen removal from the medium solution was greatest by 45 and 50 day old plants at the higher N treatments. Phosphorous and K removal also increased with plant age. Medium solutions were tested and analyzed again, 10 days later. Nitrogen removal, 10 days later, was greatest for 50, 55 and 60 day old plants at the higher N treatments. Phosphorus removal was greatest by 55 and 60 day old plants whereas K removal increased up to day 60 through all age groups. Total N, P and K in the tissue reflected nutrient removal rates; however, no differences in dry weight due to N treatment were detected. In a second experiment, to determine the age at which dry weight is affected by N treatment, plants of one age group were treated with either 10, 30, 50 or 70 ppm N. Shoot dry weights did not differ until day 27 when plants grown at 10 ppm were smaller than for other treatments. As plants aged, higher levels of N were required to prevent growth reduction. These results indicate that age influences the N removal rate from the medium solution of container-grown plants. This relationship affects the amount of N applied to the medium solution to satisfy plant N requirement.