3O2 SOILS AND FERTILIZERS 



destroy the beneficial as well as the injurious soil 

 organisms. A good sanitary condition of the soil is 

 as essential for the production of crops as are suitable 

 hygienic surroundings for the rearing of live stock. 

 Sunlight and air are important factors in bringing about 

 an improved sanitary condition of diseased soils. 



By the rotation of crops many bacterial diseases, as 

 flax wilt and clover sickness, are controlled. Some of 

 these are disseminated by the use of infected seed. 

 By sprinkling the seed grain with a disinfectant as a 

 dilute solution of formalin (i pound of formalin in 50 

 gallons of water) bacterial diseases, as grain smuts, 

 are held in check. Low forms of plants, as fungi, 

 also develop in soils when conditions are favorable, 

 and take an important part in changing the char- 

 acter of the soil. Their action may be either beneficial 

 or injurious, depending upon the condition of the soil. 

 There is a very close relationship between soil san- 

 itation, which results in the avoidance of crop diseases, 

 and the quality and yield of agricultural products. 



357. Influence of Crowding Plants in the Seed Bed. - 



The number of plants which a seed bed should produce 

 is dependent mainly upon the supply of water and plant 

 food. By means of thick or thin seeding, the general 

 character of crops may be influenced within definite 

 limits. Either an excessive or a scant amount of seed 

 gives poor results. If overcrowded, plants fail to de- 

 velop normally either for want of plant food or water, or 



