slope. Cultivation beyond that required to facilitate grading will 

 usually only increase erodibility and should be avoided. 



b. Fertilization. Nutrient supplies in regularly flooded salt 

 marshes are usually adequate, particularly in established marshes in 

 sediment-rich estuaries. Large quantities of nutrients are stored in 

 fine-grained sediments, and this supply is regularly augmented by fresh 

 deposits. However, fertilizers can be a useful tool in establishing new 

 stands of marsh under certain circumstances. Freshly deposited or expos- 

 ed sandy substrates are usually deficient in nutrients, particularly ni- 

 trogen and phosphorus. The addition of these nutrients will accelerate 

 growth thereby shortening the time that establishing plants are most vul- 

 nerable to waves and currents. (Woodhouse, Seneca, and Broome, 1972, 

 1974, 1976; Garbisch, Woller, and McCallum, 1975). 



Fertilizer response is usually, but not always, confined to sandy 

 substrates. Deficiencies acute enough to severely hamper plant estab- 

 lishment have been found on heavy-textured soils (Broome, in preparation, 

 1979) (Fig. 28). So far these appear to be confined to eroding shore- 

 lines but this problem could be more widespread. Nutrient supply should 

 be examined wherever unusual difficulty in marsh plant establishment 

 occurs, regardless of substrate texture or origin; field tests are the 

 only reliable indicators of fertilizer response under marsh conditions. 

 Chemical tests and their interpretation are considerably less advanced 

 for marsh soils than for upland soils. 



Demonstrated fertilizer response of salt marsh species has been to 

 nitrogen and phosphorus. Benefits from additional potassium or micro- 

 nutrients are unlikely under salt or brackish water conditions. 



Form of nitrogen is important. Nitrate is subject to rapid deni- 

 trification under anaerobic conditions (Patrick and Mahapatra, 1968) . 

 Ammonia is utilized more efficiently by smooth cordgrass than the ni- 

 trate form, just the reverse from most upland plants (Gosselink, 1970; 

 Woodhouse, Seneca, and Broome, 1976; Mendelssohn, 1978). This is pro- 

 bably true for other marsh species because ammonia is the normal form 

 of nitrogen existing under anaerobic conditions. Results with urea 

 have been similar to those with nitrate (Broome, in preparation, 1979). 



Conventional materials such as ammonium sulfate and triple super- 

 phosphate are usually the most economical fertilizers for marsh plant- 

 ings. Slow-release fertilizer such as Osmocote and magnesium-ammoni- 

 um-phosphate may be very effective on marsh plantings (Garbisch, 1977) 

 but there is no indication that these materials are better than con- 

 ventional forms, properly used (Broome, in preparation, 1979). For 

 example, 50 kilograms per hectare each of N, P2O5, and K2O from soluble 

 sources placed in the planting hole was as effective as 100 kilograms 

 of nitrogen plus phosphate and potash from Osmocote applied in the 

 furrow (Fig. 29). Slow-release materials may permit the use of lower 



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