LIGHT VERSUS HEAVY GRAZING 95 



Disking and Harrowing. — Sodgrasses often decline in yield 

 when the surface of the sod becomes tightly bound. Several 

 factors may be responsible for this decline. Generally, however, 

 the growth of the vegetation is held in check because of root 

 competition, the roots in the upper few inches of soil being over- 

 crowded. ]\Ioreover, where the soil is deficient in lime the 

 decaying roots may bring about acidity. This is indicated by 

 the presence of moss and other weeds that are adapted to acid 

 lands. Harrowing or otherwise breaking up the tightly bound 

 sod may therefore be beneficial, if for no other reason than that 

 of aerating the soil and improving its physical properties. 



The investigators found only a very slight difference in the 

 yield of the disked or harrowed areas as compared with those 

 untreated. On the whole, the cost of the treatment was not 

 justified on the basis of the increase in the yield. Disking or 

 harrowing, no matter how carefully done, tore or cut the sod to 

 some extent. On the other hand, the cultural treatment was 

 found advantageous in that it broke up and distributed the 

 droppings from the animals grazed. This is the statement of 

 Carrier and Oakley: 



The indiscriminate recommendation of cultural treatment of pastures is a 

 serious mistake. The experiments at Blacksburg, as a whole, do not neces- 

 sarily prove the futility of such treatment, but the critical observations made 

 throughout the five years leave no doubt that cultural treatment, by almost 

 any means, must be conducted with care and judgment. In view of the 

 results of its investigations, the Experiment Station cannot at the present 

 time recommend cultural treatment of pastures to the farmer. 



Light versus Heavy Grazing. — Overgrazing is without doubt 

 the chief cause of the depletion of bunchgrass or other non- 

 sodded lands. So convincing is this belief over the devastated 

 grazing grounds of the far West that it is commonly accepted as 

 holding generally for bluegrass and other sod pastures. The 

 studies at the Virginia Station, however, emphasize the danger 

 of applying the results of treating one form of plant growth to 

 a very different type. 



Comparatively close grazing of well-established bluegrass 

 pasture resulted in the production of many more pounds of beef 



