FORAGE CROPS 197 



the case, it is the most satisfactory method available for 

 comparing the different crops as a whole. Not only is 

 the root system of most ordinary crop plants within the 

 four-foot zone, but also this is the region where a large 

 part of the alkali is concentrated. On most alkali la^nds 

 the salts in the first four feet of soil may be drawn toward 

 the surface where they will concentrate. 



Forage Crops have given more satisfaction for use on 

 rather strong alkaline soils than other cultivated crops as 

 a general rule. Quality in fruit, vegetable, sugar, fiber, 

 and grain crops is frequently so impaired by alkali that 

 the crop is practically worthless for the product ordinarily 

 obtained, but since quantity is the chief requisite for forage 

 the crop serves its purpose when a good yield is obtained. 

 Leguminous plants as a family are very sensitive to alkali, 

 especially sodium carbonate. Hilgard (12) states that 

 alkali even when present in quantities as small as 200 or 

 300 parts per million is generally harmful to most of the 

 legumes. Alfalfa and sweet clover, especially the latter, 

 however, are among the crops generally recommended as 

 being resistant to alkali. 



Alfalfa sometimes fails to give satisfactory results on 

 alkali land because it is rather sensitive in the seedling 

 stage. A good stand and healthful growth in its first 

 stages are sometimes secured by driving the alkali below 

 the seed-bed by means of a heavy irrigation. Hilgard 

 places the limit for unaffected growth at about 1650 parts 

 per million total salts, about 300 parts per million of 

 sodium carbonate, or about 1390 parts per million of sodium 

 sulphate. Kearney (17) places the highest successful 

 amount at 4000 parts per million of white alkali, while 

 Means and 'Gardner (22) state that 4000 parts per million 

 of white alkali caused young alfalfa to become sickly or 



