470 INVESTIGATION BY CULTURE EXPERIMENTS 



crops as green manure, the corn yields in the three-year rotation 

 were 54.6 bushels in 1906 and 51.5 bushels in 1907, compared with 

 66.4 bushels and 73.6 bushels on plot 9 with nitrogen applied, and 

 compared with 18.3 bushels and 27.7 bushels on plot 8 with no 

 nitrogen for the same years. 



The growing of legume crops and the use of farm manure (and 

 possibly limestone) are the only recommendations made for the 

 improvement of these well-drained sand soils, although further 

 tests may show profit from potassium until more organic matter is 

 supplied. As a rule, clover cannot be grown successfully on this 

 land, but cowpeas and soy beans are well adapted to such soil, and 

 they produce very large yields of excellent hay or of grain very 

 valuable for feed and also for seed. 



Under the best conditions, with good preparation and heavy 

 manuring, alfalfa can be grown on this sand soil, more than five 

 tons of alfalfa hay per acre in one year having been grown on part 

 of the Green Valley field. Both soy beans and alfalfa should be 

 inoculated with the proper nitrogen-fixing bacteria. 



Heavy applications of ground limestone also may be especially 

 beneficial in getting alfalfa started. 



(It should be kept in mind that residual sand soils, such as are 

 found in the Coastal Plains soil province in the South Atlantic and 

 Gulf States, are, as a rule, very deficient in mineral plant food, as 

 well as in nitrogen.) 



Peaty swamp lands. Peat is chiefly of two kinds, one being known 

 as moss peat and the other as grass peat. Moss peat consists 

 largely of dead and decaying sphagnum moss, and grass peat of 

 the residues of coarse swamp grass, sedge, flags, etc. Probably 

 most of the beds in Ohio, Indiana, Illinois, and Iowa are grass peat, 

 although there is some moss peat in northern Illinois. Indeed, in 

 the detail soil survey of Lake County, Illinois, one swamp of several 

 acres was found where the sphagnum moss is still growing luxuri- 

 antly over a bed of moss peat. 



Where the soil consists very largely of decaying peat to a depth 

 of 30 inches or more, it is called deep peat. 



As shown in Table 15, deep peat contains in one million pounds 

 of surface soil about 35,000 pounds of nitrogen, 2000 pounds of 

 phosphorus, and 2900 pounds of potassium. This shows in the 



