sand supplies. Response is likely to be much less on sites with active 

 sand accretion. However, the initial establishment period is usually 

 the most critical for dune plantings and even a moderate acceleration of 

 growth at this point may mean the difference between success and failure, 

 particularly on the more exposed sites. Fertilization, by reducing the 

 limitations imposed by nutrient supply, enables better plant growth during 

 favorable periods. Fertilization is usually discontinued in the active 

 sand zone as soon as plants are established. 



Most pioneer species, especially the major dune builders, lose vigor 

 very rapidly when they no longer receive fresh sand. They may die out 

 altogether and be replaced by plants of the intermediate zone that are 

 much less effective in sand trapping and stabilization. This is the nor- 

 mal succession in this situation and unless there are practical reasons 

 to do so, there is no point in interfering with it. However, the effect 

 of fresh sand, or the lack of it, on pioneer dune plants is in part, at 

 least, a nutrient effect and it is possible to revive sand-starved stands 

 through fertilization. This is very useful whenever it becomes necessary 

 to restore or maintain a vigorous foredune-type cover on areas that be- 

 come cut off from fresh sand. Specific suggestions for fertilizer use 

 are presented for the geographic regions later in this section. 



Suggested fertilizer schedules are based on the use of standard com- 

 mercial nitrogen and phosphate materials or mixed fertilizers of nitrogen 

 and phosphate. Conventional soluble sources are surprisingly effective 

 in light of the inability of dune sand to retain nutrients. This is 

 apparently due to the interception of nutrients as they leach downward 

 through the extensive root systems of dune grasses. Response is largely 

 to nitrogen and sometimes to phosphorous. Consequently, a ratio of 3 

 parts nitrogen to 1 part of phosphate makes a good dune fertilizer. 

 Occasionally, it may be more convenient to use commercially available 

 fertilizers containing potassium, in addition to nitrogen and phosphorus. 

 The potassium will do no harm but observable response to potassium or 

 micronutrients is unlikely as long as the dune grasses are subjected to 

 salt spray which supplies them. Where the suggested fertilizers are not 

 readily available, waste can be minimized by alternating one application 

 of 8-8-8 (8 percent N, 8 percent P2O5, 8 percent K2O) or 10-10-10, for 

 example, with two or three applications of a straight nitrogen source, 

 such as ammonium nitrate, to approximate the suggested amounts of nitro- 

 gen and phosphate. Slow-release materials, particularly those containing 

 slowly soluble nitrogen, reduce both leaching losses and the number of 

 applications needed; however, results with these have been inconclusive. 

 Most slow-release fertilizers are not fully effective unless placed deep 

 enough to remain moist most of the time. Some slow-release materials 

 have been used to speed establishment of American beachgrass by placing 

 a small amount in each planting hole at time of planting. Although this 

 promotes rapid growth for a year or two, it may overstimulate the plants, 

 causing extensive die-out later, particularly if fertilization is not 

 maintained at the same level. All slow-release materials are consider- 

 ably more expensive than conventional sources. 



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