134 CLOVERS 



tion of an excess of irrigating waters under such 

 conditions. Overflow waters that are stagnant are 

 more injurious probably than those that are in mo- 

 tion, owing, it may be, to the less supply of dissolved 

 oxygen in the former. 



Soils suitable in themselves, but lying on stiff clay 

 bottoms or underlaid with hard pan within two or 

 three feet of the surface, will not maintain a good 

 stand of alfalfa. The plants in these may grow well 

 for a time, probably a year or two, after which they 

 will fail. The roots are not able to go down to 

 gather food. When the subsoils are simply stiff 

 clays, deep subsoiling, as already intimated, may 

 render much service, but when composed of hard 

 pan this may not be practicable. In moist climates, 

 however, reasonably good crops have been obtained 

 from soils with underlying rock not more than four 

 feet below the surface. 



The fact should not be overlooked that soils may 

 have the requisite physical conditions for growing 

 alfalfa, and they may possess in fair supply the es- 

 sential elements of plant food, and yet alfalfa will 

 not succeed at the first when sown on these, because 

 of the absence of the soil bacteria, the presence of 

 which is essential to the vigorous growth of the 

 plants. Because of this, growers should be slow to 

 conclude that alfalfa will not flourish on the soils 

 on which they sow it until they have first tried to 

 grow it on those soils that have been inoculated with 

 the requisite alfalfa bacteria. For the methods of 

 procedure in such cases see page 53. Some persons 

 claim that soils which will grow medium red clover 



