8 BULLETIN 1170, U. S. DEPARTMENT OF AGRICULTURE. 



DEFERRED AND ROTATION SYSTEM OF GRAZING. 



This system of grazing is designed to allow each division of the 

 pasture to mature a crop for two successive years before it is har- 

 vested by the cattle in the fall of each year. Grazing on each divi- 

 sion is deferred and rotated, so that each unit has an equal chance 

 to produce a maximum crop normally before it is disturbed. 



The seeds of the grasses which are scattered on the ground are 

 aided in their planting by the trampling of the cattle. This manner 

 of reseeding is highly important in some sections. 8 However, in 

 this region the advantage gained by reseeding for most of the species 

 of plants is not as great as it would be in an area that has been over- 

 grazed for a number of years. As far as it has been possible to 

 determine, there has been no measurable increase in any of the spe- 

 cies by reseeding in the rotation pasture. This has no doubt been 

 influenced to some extent by the very unfavorable seasons. The 

 greatest advantage gained here by this system of grazing is in the 

 physiological effect upon the plants. The fact that the plants are 

 allowed to mature a crop normally permits them to store up food 

 in their root systems to aid in the production of the next year's crop. 

 It is a well-recognized botanical fact that the surest way to kill 

 plants is to keep them from producing green shoots. The continual 

 removal of the early green shoots by grazing gradually reduces the 

 vitality of the plants until they finally die. Some species are much 

 more readily killed in this manner than are others. This fact is 

 well illustrated in the case of Stipa comata (western needle grass). 

 In the 30-acre pasture this grass has been greatly weakened and 

 chinned out, while in the frequently clipped quadrats it has been 

 entirely eliminated. 



Figure 2 shows the plan of the deferred and rotation grazing 

 system. Section 1 illustrates the system presented in the Yearbook 

 of the Department of Agriculture for 1915, page 309. Section 2 

 illustrates a similar plan but one in which the two successive fall 

 grazing periods proceed from C to A to B, while in section 1 they 

 proceed from C to B to A. It will be noted that section 2 pro- 

 duces the more uniform pattern and is ready to repeat directly in ♦ 

 1924, while in section 1 it repeats indirectly in 1924. In section 1, 

 division B has four rest periods in 1919 and 1920, which do. not 

 occur in any other division during the cycle. Section 1 has been 

 followed in this experiment. 



The seasonal grazing of the 70-acre rotation pasture illustrates 

 the application and management of deferred and rotation grazing. 

 These 70 acres are divided by cross fences into three parts, approxi- 

 mately equal in size. The divisions are designated A, B, and C. 

 When this pasture was first grazed in 1918, division A was grazed 

 first, or in the spring; division B second, or in the summer; and 

 division C was allowed to mature its crop normally and was grazed 

 third, or in the fall. In 1919 division B was grazed first, A second, 

 and division C was again deferred until the third period, or after 

 the crop had matured without disturbance. During the following 

 seasons divisions A and B are in turn treated as was division C 



8 Sampson, Arthur W. Natural revegetation of range lands based upon growth re- 

 quirements and life history of the vegetation. In Jour. Agr. Research, v. 3, pp. 93-148, 

 6 figs., pis. 12-23. 1914. 



