132 PRINCIPLES OF FARM PRACTICE 



If it is plowed in the fall and a liberal amount of well-rotted 

 manure is then applied, the work necessary to put the soil in 

 good condition in the spring will be much reduced. Besides, 

 the organic matter added will tend to retain moisture and 

 make the soil easy to work during the growing season. 



After this initial preparation of a garden plot has been 

 made, a rotation may be established which will meet the soil 

 requirements of the various vegetables, and, at the same time, 

 reduce the amount of manure to be applied in any one year. 

 Such a plan is sometimes known as the " three-field system." 

 It is based upon the fact that vegetables may be divided into 

 three groups, according to the richness of the soil needed for 

 their best development. The first group requires heavily- 

 fertilized soil. This group includes plants used for their 

 tops or fruits, such as cabbage, lettuce, tomatoes, and corn. 

 The second group requires soil of moderate fertility and 

 includes the root crops, such as potatoes, turnips, radishes, 

 carrots, etc. The third group requires no fertilizer unless 

 the soil is very poor. Peas and beans belong to the third 

 group. Being legumes, they can supply their own nitrogen. 



The three-field system is carried out as follows: The 

 garden area is divided into three parts; the first is richly 

 fertilized with manure balanced with acid phosphate; the 

 second is sparingly fertilized with finely divided, well-rotted 

 manure; the third is left unfertilized. On the first division 

 are grown plants of the first group; on the second, plants of 

 the second group; on the third, plants of the third group. 

 In the second year, the division which, during the first year, 

 bore plants of the first group, is planted to plants of the second 

 group, and in the third year to plants of the third group. In 

 the fourth year, as in the first year, it is richly fertilized and 

 planted to plants of the first group. The division which, 



