10 BULLETIN 652, U. S. DEPARTMENT OF AGRICULTURE. 



silt below. As the coast line is approached, as noted before, the marsh becomes 

 salt, but it is covered with practically the same depth of muck. In various 

 places in this section there are broad zones where the silt deposit between the 

 muck and the underlying subsoil is perhaps 3 or 4 feet deep and has a chocolate- 

 brown color similar to that of the soil of the Sharkey clay regions. These areas 

 are more numerous in the lower portions of the prairie. 



Along the larger rivers, especially near their mouths, the alluvial belts of 

 soil are quite wide. In these sections the rivers have laid down alluvium many 

 feet in thickness on the older deposits. The building up of these flood plains has 

 been very slow, and the marsh-grass growth has been continuous ; thus we have 

 near the top a muck with a high percentage of silt, grading down into a silt with 

 a large percentage of vegetable material at a depth of from 1 to 4 feet. Parts 

 of this alluvial section are soft, although the land immediately along the river 

 channels sometimes is quite firm. The muck is similar to that of the Missip- 

 sippi Delta section, except that the silt is well mixed with it instead of occur- 

 ring in alternate layers. 



DRAINAGE CHARACTERISTICS OF SOILS. 



As the ultimate success of most of the reclamation districts of this section 

 depends on the successful drainage and cultivation of the muck lands, a rather 

 detailed study of them was made. In investigating these soils it was the en- 

 deavor to get a careful description of their physical characteristics, to find the 

 percentage of water by volume that they would contain when in good condition 

 for growing crops, and to ascertain the amount of water they would hold when 

 completely saturated. 



The muck is a mass of vegetation in varying stages of decay and contains 

 varying amounts of river silt. It differs in character according to the kind 

 of vegetation from which it was derived; thus the muck of the cypress swamp 

 is much darker and less fibrous than the muck or turf of the open, grass-covered 

 prairie. Also, according to stage of decay, it may be tough and fibrous and able 

 to bear the weight of a man, or it may be soft and even semifluid if considerable 

 water be present. Being the result of growth rather than of deposit, it has 

 been formed in layers, the depth of which depends largely on the time in- 

 volved. When a layer of vegetation is covered with a heavy layer of silt all 

 addition to the former ceases, and if conditions be favorable a new layer of 

 vegetation is formed on the silt above. Thus we have strata of muck varying 

 in thickness from an inch to several feet, with intermediate strata t>f silt of 

 depths of from 1 inch to perhaps 2 feet. About half of the waterways that 

 extend through these swamps are streams of tidal erosion ; along these streams 

 the high ridges of river silt are absent, and the muck is specially deep. Bayou 

 des Allemands, Wax Bayou, and Little Wax Bayou are streams of this char- 

 acter. 



The samples of muck examined were taken at just sufficient depth below the 

 surface to insure the optimum percentage of water — i. e., the amount of mois- 

 ture considered by local plantation owners to be the best for the growth of 

 general field crops. No samples were taken immediately after a rain or after 

 a long dry period. At the time of taking the samples a description of each 

 field was made, including depth of water table, length of time the field had been 

 drained and cultivated, time since last rainfall, character of original vegeta- 

 tion, nature of present crop, and other conditions peculiar to the tract in ques- 

 tion. The following tables show the results of tests made in the spring of 1910 : 



