THE POTATO 29 



regular pieces that cannot be cultivated con- 

 veniently. 



"2. It delays cultivation, particularly in the 

 spring. 



**3. It makes soils cold: (a) because in the spring 

 more than half of the heat that the soil receives 

 is used to warm this unnecessary water; (b) be- 

 cause its evaporation consumes heat that the soil 

 could otherwise retain; and (c) because its pres- 

 ence in the soil prevents the entrance and down- 

 ward movement of rainwater, which in the spring 

 is usually warmer than the soil. 



"4. It crowds out the oxygen from between the 

 soil grains, thus hindering the necessary decom- 

 position of organic matter in the soil. 



"5. It prevents all crop growth where it stands 

 on the soil to a sufficient depth. Where it stag- 

 nates only a few inches from the surface of the 

 soil it prevents healthy root development below 

 that depth. The shallow root system thus devel- 

 oped limits the depth from which the plant may 

 get water, and with it plant food material. 



"The occurrence of an excess of water in a soil 

 or on an area is an indication that some source 

 supplies water faster than it can be removed. The 

 water is either coming too fast or it is going too 

 slowly. Areas at the foot of uplands from which 

 numerous small or large springs run during the 

 greater portion of the year owe their wetness to the 

 excessive seepage from the upland; while reten- 

 tive clays, due to the fineness of the soil, and flat 

 muck or peat marshes, due to lack of fall, are too 

 wet primarily because the water is very slowly re- 

 moved from them. 



"It is evident that the drainage conditions on 

 an area may be improved either by hindering the 



