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



Here on the prairie under light or moderate grazing the " weeds " 

 (species other than the grasses and sedges) bear much the same rela- 

 tion to the intensity of grazing as they do in the bluegrass pastures 

 of the South 24 except that they do not crowd out the more valuable 

 species. It is therefore better to follow a system of grazing that will 

 keep the weeds down and at the same time not allow any of them 

 an opportunity to become noxious because of overgrazing. The 50- 

 acre pasture so far has been able to do this, but the gains per head 

 of the cattle have been somewhat reduced, as the pasture becomes 

 very short toward the close of the season. The rotation pasture is 

 able to accomplish the same results on a slightly reduced acreage and 

 at the same time produce a higher gain per head. 



CUPPED QUADRATS. 



The clipped quadrats were established in 1917. The vegetation is 

 cut, or clipped, close to the ground with a pair of roaching shears. 

 It is clipped uniformly closer than it would be grazed by cattle, 

 but care is taken not to destroy the plant crowns. This method of 

 quantitative determination was adopted to secure data on the period 

 of most active growth of the different species and to determine the 

 effect on subsequent growth of frequent removal of the vegetation. 



Clippings have been made after 10, 20, 30, and 40 day periods, 

 and also at the end of the season (annual). In 1919 a set of quad- 

 rats was added to include the biennial removal of the vegetation. 

 During the same year was added a series of clipped quadrats which 

 are cut in relation to the deferred and rotation system of grazing. 

 The data from these are not included, as the quadrats are not old 

 enough to be of more than minor significance. Duplicate square- 

 meter quadrats were used. The arrangement of the quadrats and 

 their appearance at the close of the grazing season in 1919 are shown 

 in Plate VIII, Figure 2. The quadrats are located in the isolation 

 transect of the 100-acre pasture and are therefore not disturbed by 

 grazing. 



It is recognized that there are individual differences between the 

 quadrats. However, they are not great enough to overcome the 

 effects of different intensities of clipping or to obviate the original 

 conception of this method of analysis. The quadrats were clipped 

 for the first time in June, 1917. The vegetation was removed from 

 all quadrats on the same date. The vegetation on them had not been 

 disturbed since 1915 and was only lightly grazed during that season. 

 The total vegetation from each quadrat was weighed (in grams) both 

 green and after becoming air dry. The weights from all quadrats 

 ranged from 235 to 263 grams green and from 168 to 186 grains dry. 

 This included all old growth along with that of the current year. 

 The subsequent clippings have been divided, as shown in Table 9, 

 into the individual dominant species and into other important groups 

 at the time of cutting and weighed both green and dry. Pertinent 

 notes were made of the stage and quantity of growth of all species. 



The periods for clipping are now fixed, so that May 1 is considered 

 the date from which all periods start each season. For example, 

 the first clipping is made on May 10 for the 10-day periods, May 



M Carrier, Lyman, and Oakley, R. A. The management of bluegrass pastures. Va. 

 Agr. Exp. Sta. Bui. 204, 18 pp., 8 col. figs. 1914. 



