RANGE PRESERVATION AND EROSION CONTROL. 



19 



tamped firmly in cans 14 inches wide and 17 inches high. Six large 

 test pots were used, three of which contained eroded and three non- 

 eroded soil, and each was planted to five seedling plants as follow.-: 

 One set, consisting of one pot of eroded and one of noneroded soil, 

 to a pedigreed field pea known as Kaiser variety; one sel to native 

 bromegrass, locally called wild oats (Bromus marglnatus semi- 

 nudus) ; and the third set to a pedigreed wheat known as Kubanka 

 No. 1440. 



The pots were hermetically sealed and so arranged that all the 

 water loss from the soil had to pass through the plants in the form 

 of transpiration or evaporation. The pots were weighed at regular 

 intervals and water was added to the soil so that the moisture content 

 was kept practically constant. Throughout the experiment the aver- 

 age moisture content was about 30 per cent, a supply ample to pro- 

 duce the most vigorous growth on both soil types. 



Owing to the action of the elements on the two soils studied there 

 was an interesting and significant difference both in their chemical 

 and physical properties. The percentages of salts important t? the 

 growth and development of plants in these soils are as follows : 



Taijle 7. — Salts important to the growth and development of plants on the two 



soils studied. 



Soil. 



Lime 

 (CaO). 



Potash 

 (K 2 0). 



Phos- 

 phoric 

 acid 

 (P2O5). 



Total Loss on 

 nitro- ignition 

 gen. (humus). 



Per cent. 



Eroded 1. 36 



Noneroded 1. 49 



Per cent. 

 1.53 

 1.30 



Per cent. 



0.22 



.33 



Per cent. Per cent. 



0.156 1 - 6.64 



.488 14.65 



In all the constituents considered except potash, the noneroded 

 soil is much the richer. The greatest difference is found in the total 

 nitrogen content, one of the most important of plant foods. This is 

 due to the fact that a large proportion of the nitrogen compounds 

 are more or less soluble in water and consequently had been largely 

 washed out of the eroded soil. 



The chief physical properties are those which affect the total water- 

 holding capacity of the soils and the amount of water that can be 

 absorbed from them by a plant. These properties are intimately as- 

 sociated with the amount of organic matter in the soils. The eroded 

 soil was found to have a maximum water-holding capacity of 46.8 

 per cent as compared with 67.2 per cent in the case of the noneroded 

 soil. At the same time the soil moisture which can not be absorbed 

 by the root hairs of the plant, and which is therefore termed " non- 

 available" water, was found to be 15.6 per cent in the eroded soil 

 and 19.3 per cent in the noneroded soil. Owing to this the combi- 



