These trials indicate that once full cover is attained, fertilization 

 can be discontinued for one year without incurring any serious decrease in 

 cover. It is much too early to anticipate the second-year effect. Stands 

 from which fertilizer was withheld this year do give the appearance of being 

 nitrogen-deficient and decreasing in vigor. From this, one would suspect 

 that the second-year effect might be more drastic than is suggested by the 

 data in Table 7, and that some fertilizer will be required in alternate years 

 at least, and perhaps every year, in order to maintain vigorous stands. 

 Trials are set up now which should provide, over the next two or three years, 

 a much better basis for establishing a maintenance fertilizer program. 



e . Regeneration of Stands 



(I) American beachgrass . It is rather generally recognized that 

 stands of American beachgrass often tend to weaken and die out once an area 

 becomes stabilized and new sand ceases to enter it. This has given rise to 

 the idea that the continuing accumulation of sand is essential to the normal 

 growth and survival of this species. This study has shown that this plant 

 does thrive on sand accretion, and can trap and come through quite large 

 quantities of sand during the growing season. However, a large part of the 

 beneficial effect of the accumulating sand must be attributable to an in- 

 crease in the supply of nutrients (primarily nitrogen) associated in some 

 way with the trapped sand. 



One trial, initiated in September 1963 to indirectly test this hy- 

 pothesis, was located on a large dune situated about one-fourth of a mile 

 from the surf. This area had been planted about 5 years earlier on what 

 had been a "live" dune, and then a strong foredune was constructed between 

 it and the surf. The foredune almost completely stopped sand movement into 

 the area except at a small spot about 100 yards south of the experimental 

 site. The grass in this planting grew slowly for the first year or two, 

 and then gradually began to deteriorate so that by September 1963 less than 

 a 50 percent stand of very stunted plants remained except at the small spot 

 which continued to receive sand. There was a very noticeable revival of 

 growth on the treated plots during the 1964 growing season, and by the 

 summer of 1965, the stand had thickened considerably. Growth measurements 

 taken in August 1965 are shown in Table 8. 



TABLE 8 



Effect of Fertilizer (Nitrogen, Phosphorus, Potassium) in Reviving 

 Degenerate Stands of American Beachgrass 



Treatment 



Growth lb/acre, August 1965 



Check - no fertilizer 240 



N - 33 lb. N September, April, July (1963) 2129 



NP - N as above + 50 lb. P2O5 2261 



NPK - NP as above + 50 lb. K2O 2521 



Least Significant Difference - .05 795 



Least Significant Difference - .01 1092 



Coefficient Variabi I ity 44$ 



16 



