EFFECTS OF DIFFERENT SYSTEMS OF GRAZING. 35 



turity of the grasses may show an improvement in germination, 

 but from all available data it appears that the seeds of many of the 

 important grasses have a low degree of vitality. These grasses are 

 able to maintain themselves under normal conditions by their strong 

 vegetative growth and in favorable seasons by the production of a 

 large number of seeds, a few of which will grow and become estab- 

 lished. 



SEEDING EXPERIMENTS IN NATIVE SOD. 



A number of attempts have been made each year to establish some 

 of the cultivated forage crops in the native sod without breaking it. 

 Trials have been made with brome-grass, alfalfa, sweet clover, and 

 the wheat-grasses both with and without disking the sod. These 

 trials have furnished but slight encouragement for such a practice. 

 The dry seasons may have prevented securing a stand, as practically 

 every year some seedlings start growth but dry up before the end of 

 the season. The native sod is already supporting all the vegetation 

 possible, and unless this is destroyed by breaking there is but slight 

 chance of anything else being able to compete with it. 



SOIL M0ISTURE. 



Soil-moisture determinations have been made in each of the con- 

 tinuously grazed pastures every year since the experiment started in 

 1916. The soil samples have been taken around the quadrat area in 

 each case. 



The first foot of soil has been filled with water at the beginning of 

 the season each year, but in all pastures has been reduced to the 

 minimum before the end of the season every year since 1917. 



The second foot of soil was filled with water at the beginning of the 

 seasons of 1916 and 1917. It has not been completely filled since that 

 time during any part of any season. 



The moisture in the third^f oot has decreased from about 20 per cent 

 in 1916 to 11 per cent in 1921 in all pastures. The same general re- 

 duction has held true for the fourth foot. The reduction of moisture 

 in the fifth and sixth feet did not become pronounced until 1919. 

 This was also true for wheat plats in the rotations at the station. 



The soil-moisture data show very clearly that there has been a re- 

 duction of moisture in the sixth foot of all pastures except the 30-acre 

 pasture. In this pasture there has been but little change in moisture 

 content in the sixth foot since the middle of the season of 1919. This 

 has no doubt been caused by the intense grazing. All of the plants 

 except Artemisia frig Ida are eaten before they have a chance to use 

 moisture to a depth of 6 feet. The available moisture at this depth 

 has not been required by A. frigida because of the reduction of com- 

 petition with other species for moisture above the sixth foot. 



PALATABILITY OF THE VEGETATION. 



The grasses annually produce from 45 to 55 per cent of the dry 

 weight of all species. This fact is one of the highest significance, 

 since it indicates an area of high grazing value for cattle. 



In general, cattle and horses use a grass range to better advantage than sheep, 

 bneep relish tender green foliage and the grains of many grasses, but they oat 



