FOEAGE-CKOP EXPEEIMENTS AT SAN" ANTONIO. 7 



poses of practical application the notes and comments concerning 

 each crop or experiment be given the greater emphasis and that any 

 broad generalizations from the figures in the tables be avoided. 



THE SOIL ON WHICH THE. EXPERIMENTS WERE CONDUCTED. 



The San Antonio Experiment Farm is located in the southern 

 extension of what is called the ''Black Prairie region," known 

 geologically as the Upper Cretaceous formation, and is representative 

 of- a large portion of central Texas extending from the Oklahoma line 

 to the Rio Grande. The surface soil, which is a black, clayey loam, 

 is capable of absorbing a high percentage of moisture, but tends to 

 puddle and bake. It is very sticky when moist, and all tillage opera- 

 tions are difficult because the plows and cultivators do not scour. 

 The subsoil is of about the same mechanical composition as the 

 surface soil, but it often contains more lime, which occurs as gravelly 

 concretions. The subsoil is also much lighter colored, probably 

 due in part to the lack of organic matter as well as to the larger 

 proportion of lime. When supplied with plenty of water, the soil is 

 usually very productive and has proved well adapted to growing 

 many of the ordinary forage crops. 



CROPS ORDINARILY GROWN FOR FORAGE. 



The crops that are generally grown in the San Antonio region for 

 forage are sorghum, oats, Johnson grass, millet, cowpeas, and corn, 

 while alfalfa is grown to a limited extent where irrigation water is 

 available. Of the crops mentioned, sorghum, oats, and Johnson 

 grass are the most common, and they rank in the order named in 

 popularity and value. The native wild grasses aro used only for 

 pasture. Most farmers grow only sorghum for forage, and conse- 

 quently it has been deemed advisable to test other forage crops with 

 a view to suggesting some practical diversification as a basis for 

 systematic crop rotation. The native cactus, or Opuntia, is being 

 used as a forage crop and has proved to be a valuable addition to 

 the list, especially during unfavorable seasons.^ 



SORGHUM. 



Experiments designed to determine the most prolific varieties, the 

 best methods of planting, the proper rate of seeding, and the best 

 date of planting sorghum have been carried on at the San Antonio 

 Experiment Farm during the past five years. 



1 For information concerning this crop, consult the following bulletins: 



Griffiths, Da^^d. The Priclsly Pear as a Farm Crop. Bulletin 124, Bureau of Plant Industry, U. S. 

 Dept. of Agricultm-e. 190S. 



The "Spineless" Prickly Pears. Bulletin 140, Bm-eau of Plant Industry, U. S. Dept. of Agri- 

 culture. 1909. 



The Thornless Prickly Pears. Farmers' Bulletin 4S3, U. S. Dept. of Agricultm-e. 1912. 



[Cir. 106] 



