4 BULLETIN 1039, U. S. DEPARTMENT OE AGRICULTURE. 



On newly irrigated land small grains or flax usually are sown 

 for a cash crop, and on old irrigated land a considerable acreage of 

 these crops is grown in rotations following a cultivated crop or as a 

 nurse crop for alfalfa. 



SOIL. 



The soil of the Belle Fourche Experiment Farm and of the sur- 

 rounding section is a heavy, stiff clay, or gumbo, classified by the 

 Bureau of Soils as Pierre clay.* This soil occupies about one-third 

 of the area of western South Dakota. 



It contains about 35 per cent of clay, 43 per cent of silt, 13 per cent 

 of very fine sand, and only a small quantity of humus. The soil 

 is of residual origin and contains considerable quantities of calcium, 

 magnesium, and sodium salts. Alkali is a problem only in seeped 

 areas. 



The soil when wet is exceedingly sticky and is almost impervious to 

 water.^ Upon drying, it checks rapidl3^ later forming large cracks 

 which permit the entrance of water. The soil can not be plowed 

 when wet and is difficult to plow when dry, but disking and harrow- 

 ing are comparatively easy if done at the proper time. Land plowed 

 in the fall when dry becomes quite mellow in the spring from the 

 alternate contraction and expansion caused by temperature changes 

 during the winter. The soil contains ample quantities of plant food 

 and with sufficient rainfall is capable of producing large yields of 

 grain. 



NATIVE VEGETATION." 



The native vegetation of the locality consists largely of western 

 wheat-grass {Agropyron smith-ii, A. occidentale) and buffalo grass 

 {Bulhilis dactyloides) . Grama grass {Bouteloua oligostachya) and 

 needle grass {Stipa comata) are frequently found. Buffalo grass 

 usually occupies the higher and lighter soils, especially where Pierre 

 clay is the soil type. Western wheat-grass is confined mostly to the 

 lower slopes and bottoms. On bottom lands subject to overflow this 

 grass produces considerable hay of excellent quality. 



Weeds, such as sunflower (rielianthiis jjefiolarls) , giimv^eed {Grin- 

 delia squarrosa)^ goosefoot {Atriplex volutans), and wild parsley 

 [Peucedanum foeniculaceum) ^ are plentiful. They are particularly 

 abundant following extremely dry seasons, when the grass maj^ be so 

 injured that weeds are practically the only vegetation. Poverty weed 

 {Iva axillaris) is of considerable economic importance because of the 



* Strahorn, A. T., and Mann, C. W. Soil survey of tho Bollo Fourche area, South 

 Dakota. In U. S. Dept. Agr., Bur. Soils Field Opcr., 9tb Rpt., 1007, p. 888. 1909. 



^Mathews, O. R. Water penetration in the gumbo soils of the Belle Fourche Reclama- 

 tion Project. TJ. S. Dept. Agr. Bui. 447, 12 p.. 4 fig. 191G. 



" Adapted from U. S. Dept. Agr. Bui. 297, p. ". 1915. 



