76 BULLETIlSr 355, IT. S. DEPARTMENT OF AGEICULTTJKE. 



means the presence of a large supply of nitrogen. This is usually so 

 great that practically no attention need be given to this element, but 

 it occasionally happens that acid marsh soils are so cold on account 

 of their wetness that nitrification takes place with extreme slowness 

 and there is not a sufficient supply of this element made available. 

 Under such conditions the use of some form of lime to correct the 

 acidity and hasten nitrification is very beneficial. This is discussed 

 on page 62. Manure is often beneficial to marsh soils and should be 

 applied when practicable. (See Ref. 3, p. 613.) 



The most marked weakness of marsh soils is with respect to the 

 chemical elements, phosphorus and potassium. While, of course, 

 all of the vegetation which causes the accumulation of organic matter 

 in the marsh contained potassium when it was growing, this element 

 is often leached out of such soils as they accumulate to such an extent 

 that there is not left sufficient to supply the needs of growing crops. 

 For this reason barnyard manure or some commercial fertilizer con- 

 taining potassium must be used. It is frequently found that marsh- 

 lands give fair yields for a few years after reclamation before this 

 marked need of potassium develops. This is because some of the 

 vegetable matter most recently formed still contains considerable 

 potassium, and this becomes available through its active decomposi- 

 tion. As a rule, however, fertilizers containing this element must 

 be used on such lands within a few years after their reclamation. 

 The pliosphorus needs of marsh soils are quite variable. Marshes 

 which were formed in regions containing considerable limestone, and 

 especially in regions of glacial soils formed from limestone, usually 

 contain a considerable quantity of phosphorus which was deposited 

 in them from surrounding highlands and which becomes available 

 to growing crops. It is often found, therefore, that marshes of this 

 character are not acid and do not show a marked need of phosphorus 

 fertihzers for some years after their reclamation and cultivation. 

 Practically all other marsh soils do require phosphate fertihzers just 

 as much as potassium. The large amount of organic matter in marsh 

 soils may make profitable the use of raw rock phosphate with ordinary 

 field crops. This cheap form of phosphate fertilizer therefore is often 

 preferable to more expensive forms for use on such land. 



On account of the unbalanced fertility conditions of these soils, 

 it is usually much more economical, when farms contain upland as 

 well as marshland, to use the barnyard manure produced on the 

 farm on the upland soil, which requires the nitrogen which it con- 

 tains as well as the other elements, and to purchase commercial 

 fertilizers containing potassium and phosphorus for the marsh soils. 



Physical Tuanagement. — Marsh soils are usually very loose and 

 ligiit in structure, so that growing crops do not find a good foothold 



