apart and approximately 18 meters long in a randomized complete block 

 design with three replications. The rows were perpendicular to a 

 drainage creek and extended over the elevational range of S. alterniftora 

 at this location. The fertilizer was applied in furrows under each row 

 which was opened by sweeps on a tractor the day before transplanting. 

 The transplanter closed the furrows and covered the fertilizer. The 

 dredge spoil, which is almost pure sand, was deposited during November 

 1971. However, transplanting was delayed until 28 June 1972 (later than 

 ideal) because extensive grading was necessary to prepare a suitable 

 area for the experiment within the elevational range of S. alterniftora 

 which is only about 30 centimeters at this location (the elevational 

 range of the grass is approximately equal to the tide range at this 

 location) . Plant samples were taken 4 October 1972 by clipping one plant 

 from each row. Data recorded included dry weight, number of flowers, 

 number of center culms and number of rhizome culms per plant. 



Fertilization enhanced first-year growth considerably (Tab. 44). 

 There were significant (0.05 level) increases in dry weight and number 

 of flowers and a highly significant (0.01 level) increase in the number 

 of center culms due to nitrogen fertilization. The number of rhizome 

 culms was not affected by nitrogen. There were highly significant 

 increases in dry weight, number of flowers and number of center culms due 

 to phosphorus fertilization. There was a significant increase in number 

 of rhizome culms due to phosphorus. Unlike results from experiments in 

 the natural marsh, there was no nitrogen-phosphorus interaction. The 

 Drum Inlet site was freshly deposited dredged material of almost pure 

 sand. The response of the transplants to fertilizer is evidence of the 

 low nitrogen and phosphorus content of this material. It is likely that 

 dredged material higher in silt, clay and organic matter would provide 

 adequate nitrogen and phosphorus for maximum growth of transplants during 

 the first growing season. 



c. Summary . Increased growth of S. alterniftora in response to 

 applications of fertilizer indicates that the productivity of some salt 

 marshes is limited by the supply of nutrients. The standing crop of 

 aboveground shoots of salt marsh growing on a substrate of sand was 

 increased significantly by additions of nitrogen alone and increased about 

 threefold when phosphorus was also supplied. In a marsh developed on 

 finer-textured sediments, nitrogen fertilizer doubled the standing crop 

 of short Spartina, but there was no response to phosphorus. There was no 

 growth response from applications of iron to support previous speculation 

 that iron nutrition might be a particularly important factor causing the 

 chlorotic appearance of short Spartina and reducing its productivity. 

 The chlorotic condition was remedied by additions of nitrogen. 



The response of short Spartina to nitrogen implies that a part of the 

 difference in productivity between the tall and short forms is due to the 

 amount of nitrogen available to the plants. Many other environmental or 

 possibly genetic factors or combinations of factors may be responsible 

 for producing the short form of S. alterniftora. The factor most often 

 implicated is that of salinity. High salinities will stunt Spartina and 



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