much dry matter as the check plots. The nitrogen content of the plant 

 tissue also increased as the amount of nitrogen fertilizer was increased, 

 indicating that uptake was more efficient than in the tall height zone. 

 The average recovery of nitrogen by the grass shoots in plots receiving 

 336 kilograms per hectare of nitrogen was 13 percent. This more efficient 

 recovery of fertilizer nitrogen is probably due to the greater amount of 

 roots at the soil surface in the short height zone and that loss due to 

 flooding is probably less than in the tall height zone. Another possible 

 difference is that the nitrogen supply in the tall height zone is adequate 

 and less of the fertilizer-nitrogen is used, while nitrogen is in short 

 supply in the short height zone. The efficiency of uptake of nitrogen is 

 less than at Ocracoke even in the short height zone. The less frequent 

 flooding at Ocracoke may allow the fertilizer to remain in place and 

 available for uptake for a longer period of time. 



A fertilizer experiment was begun at Oak Island in 1972 to determine 

 if phosphorus was a limiting factor in productivity at this location as 

 for Ocracoke. At the end of the first growing season there was no signif- 

 icant yield increase due to phosphorus fertilization (Tab. 40). The 

 highest rate of nitrogen nearly doubled the yield of short S. altevniflora 

 compared to the check, and plots which received nitrogen were much greener, 

 but again the tall did not respond to fertilization. The lack of response 

 to phosphorus was expected due to the nature of the substrate at Oak Island. 

 The fine-textured reduced sediments have a greater potential for supplying 

 phosphorus than the sand at Ocracoke. However, the experiment was continued 

 during the 1973 growing season and the response to phosphorus and nitrogen 

 was significant (Tab. 41). Apparently, as yields increase due to fertili- 

 zation the supply of phosphorus in the soil becomes limiting. 



b. The Effect of Fertilizer on Seedlings and Transplants . To deter- 

 mine if the addition of fertilizer would enhance propagation of S. altevni- 

 flora, fertilizer plots were established on seedlings growing on dredged 

 material at Beaufort. Seeds were planted on 4 April 1972 in the inter- 

 tidal zone of a pile of sandy dredge spoil, which had been in place for 

 about 1 year. The seed were hand broadcast and covered by six sweeps 

 mounted on the tool bar of a tractor, followed by a section harrow (Fig. 

 22) . After the seedlings were established, a randomized complete block 

 fertilizer experiment with three treatments (nitrogen, nitrogen -phosphorus, 

 check) and three replications was superimposed. Rates were 224 kilograms 

 per hectare of nitrogen (ammonium sulphate) and 49 kilograms per hectare 

 of phosphorus (concentrated superphosphate) with half applied 26 June and 

 half 26 July 1972. Plots were 1.22 meters by 7.62 meters with 1.22-meter 

 borders. Samples were harvested 5 October 1972 by cutting a swath 0.6- 

 meter wide by 6-meters long from each plot at ground level with a Jari 

 mower. The samples were dried at 70° Centigrade and weighed. 



The dry weight of seedlings at the end of one growing season was 

 increased from 3,470 kilograms per hectare to 9,340 kilograms per hectare 

 by the addition of nitrogen. Where nitrogen and phosphorus were applied, 

 the dry weight was increased to 10,800 kilograms per hectare (Tab. 42). 

 These results indicate that at this location fertilizer was beneficial in 



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