The spacing and pattern should be determined by the characteristics 

 of the site and the objective of the planting. A strip of American beach- 

 grass, 8 to 12 meters wide, planted 45 centimeters on centers will, with 

 normal development, effectively stop the movement of windblown sand in 

 the last half of the first growing season. Small blowout areas should 

 be planted at a spacing of 45 centimeters or less. Stabilization of a 

 large area of bare sand will require a spacing of 45 to 60 centimeters. 

 This means that the cost of planting may be significantly affected by 

 the planting pattern. For example, in building a barrier dune, it is 

 essential that part of the strip be planted at a density that will stop 

 sand movement sometime during the first year. The plants should be 

 spaced at 45 centimeters. It is not necessary to plant the entire width 

 of the planned dune at this density. Further, the use of a graduated 

 spacing pattern will result in a wider, more stable dune and will cost 

 less. 



A graduated pattern that has been used successfully to build barrier 

 dunes where sand accumulation was 3 to 6 cubic meters per front meter is 

 shown in Table 1. 



Table 1. A graduated planting pattern 

 to build a foredune. 



No. 



of rows 



Row spacing 

 (m) 





4 



1.20 





4 



0.90 





4 



0.60 





4I 



0.45 





4 



0.60 





4 



0.90 





4 



1.20 



^Center of dune. 



With this planting pattern, the dune growth is more rapid near the 

 center of the planted strip for the first 2 or 3 years, and the dune will 

 slope gently to the outer edges. Sand accumulation will increase near 

 the edges as the more widely spaced plants fill in and increase trapping 

 capacity. The dune cross section will attain a stable form (Fig. 24). 

 Planting costs are less than half that required for a uniform dense 

 spacing. 



6 Fertilization and Management . American beachgrass 

 responds well to the addition of nutrients, and the judicious use of 

 fertilizers is useful in the management of this plant. Plant response 

 varies widely — it is least under the condition of rapid sand accumulation 

 and greatest on old, leached sands in back dunes and deflation plains. 

 Growth on sites not receiving fresh sand may be increased up to tenfold 

 by fertilization. Response is chiefly to nitrogen and occasionally to 

 phosphorus. Fertilization is used primarily for two purposes: (a) during 

 establishment, to improve survival; and (b) to maintain a vigorous protec- 

 tive cover on areas that do not receive sufficient fresh sand. 



58 



