ALFALFA 283 



rainfall, it is necessary to irrigate if good yields are to be 

 expected. 



286. Adaptation to soils. — Alfalfa will grow in many 

 different kinds of soil, but in order to produce a successful 

 stand, it must, above all, be well-drained soil. Alfalfa 

 seems to be sensitive to an excessive amount of moisture in 

 the soil during the growing season. Soils that are water- 

 logged or that have water standing over them during part 

 of the growing season are not suitable for this crop 

 until this condition is remedied by drainage ; but soils 

 that have natural drainage, or that have porous sub- 

 soils, giving natural sub-surface draining, are well 

 adapted to the crop. Soils that have a watertable 

 or a stratum of rock near the surface of the ground are 

 not well adapted because the roots will thus be prevented 

 from penetrating very deeply into the subsoil. Alfalfa 

 does not grow well in acid soils, and when this condition 

 exists, lime must be applied before a successful stand can 

 be expected. If neutral or blue litmus paper turns red 

 when placed in a sample of damp soil, the latter is acid, 

 and lime should be applied. The amount to apply per 

 acre will depend upon the degree of acidity. An applica- 

 tion of one ton of finely ground limestone or one-half 

 ton of burned lime per acre will meet the requirement of 

 almost any acid soil. There must be a sufficient amount of 

 lime in the surface soil. Some soils that have limestone 

 in the subsoil will not grow the crop successfully until 

 the surface soil is given a liberal application of lime. 



287. The soil must be fertile and well supplied with 

 organic matter. While the growing of alfalfa adds nitro- 

 gen to the soil, the plant is not able to use the nitrogen 

 from the air until it has made a fair amount of growth ; 

 consequently it must depend upon the nitrogen in the 



