CHAPTER V 



SOIL AN IMPORTANT FACTOR AFFECTING 

 PLANT GROWTH 



The growth of plants has interested thoughtful men of all ages. 

 Little by little knowledge concerning plant growth accumulated, 

 and even today all is not known. Scientists will always study and 

 investigate the growth and habits of plants. In order that a clear 

 understanding might be gained of some of the fundamental 

 principles of crop production, it is necessary to know a few facts 

 concerning the growth of plants, and note in particular to what 

 extent soils may affect this growth. 



Conditions Must be Favorable. — ^It is self-evident that a plant 

 must have favorable conditions surrounding it before it can grow 

 to its fullest development. These conditions must be favorable 

 from the time the seed is planted to maturity. 



The hfe history of a plant may be conveniently divided into 

 foxn' periods; viz., the seed or dormant period, the germination 

 period, the vegetative or growing period and the fruition or fruiting 

 period. The average farm plant passes through three of these 

 periods in contact with the soil. We shall now consider the con- 

 ditions and requirements necessary to each of these three periods. 



THE GERMI]Srx4.TI0N PERIOD 



The Germination Period a Critical One. — ^Many poor crops 

 are to be explained in no other way than that the conditions 

 during the time of germination were not favorable. Frequently 

 when the conditions are too unfavorable the seeds become moldy 

 and fail to germinate. 



Life in a Planted Seed Strives for Existence. — ^When a seed 

 is planted in the soil it is placed in a medium teeming with bacteria 

 and fungi which would feed on the seed if no resistance were offered 

 by it. Thus, as soon as a seed is placed in the ground there begins 

 at once a struggle for existence on the part of the Mfe in the seed 

 against these bacteria and fungi. When conditions are favorable 

 for the seed, it wins and sends out its roots and stem; if unfavorable, 

 the soil organisms win and cause the seed to decay. How 

 very necessary it is, therefore, that the conditions be favorable 

 during germination. 



47 



