CEREAL INVESTIGATIONS ON THE BELLE EOtJRCHE EARM. 3 



explained by the large percentage of clay and. silt it contains, these 

 amounting to 35 and 43.2 per cent, respectively. 



Table I. — Composition of Pierre clay , as determined by mechanical analysis. 



Per cent. 



Fine gravel 0. 2 



Coarse sand 1.1 



Medium sand 1. 4 



Fine sand 5. 5 



Very fine sand 13. 



Silt 43.2 



Clay 35. 



The soil is a very heavy, stiff, impervious residual clay. It is 

 somewhat deficient in humus, but is probably well supplied with the 

 mineral elements of plant food. The imperviousness of the soil and 

 the topography of the country cause considerable loss of water by 

 run-off during heavy rains. 



Plowing is difficult and expensive. Other necessary field opera- 

 tions, such as disking, harrowing, etc., are accomplished without 

 difficulty. If these operations are performed at favorable times, the 

 soil is easily put in excellent condition. 



There is considerable variation in the soil on the experiment farm, 

 even within the limits of a single field. As a general rule, the higher 

 land is lighter in texture, better supplied with humus, and more 

 productive. The lower land is heavier, more impervious to water, 

 contains less humus, and is more difficult to work and to get into 

 condition for cropping. 



NATIVE VEGETATION. 



The native vegetation of the locality consists largely of western 

 wheat-grass (Agropyron smithii, A. occidentals) and buffalo grass 

 (Bulbilis dactyloides) . Grama grass (Bouteloua oligostachya) and 

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

 usually occupies the higher and fighter 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 (Helianthus petiolaris) , gum weed (Grin- 

 deJia squarrosa), goosefoot (Atriplex volutans), and wild parsley 

 (Peucedanum foeniculaceum) , are plentiful. They are particularly 

 abundant following extremely dry seasons, when the grass may be 

 so injured that weeds are practically the only vegetation. Marsh 

 elder (Iva axillaris) is of considerable economic importance because 

 of the difficulty of eradicating it in cultivated fields. This plant 

 commonly is called gumbo weed in this locality because it is found 

 usually on the more impervious soils of the Pierre-clay type. 



