USE OF ANNUAL PLANTS IN CALIFORNIA FOOTHILLS 19 



is nearly exhausted. Swales are the last sites to dry, and most of the 

 herbage produced on swales remains green for 2 to 4 weeks longer than 

 the bulk of the vegetation on slopes. Late-maturing species growing on 

 the swales (table 3) help extend the green-forage period there. The late- 

 growing annual clovers, mainly whitetip clover, and two perennial grass- 

 like species, common spikesedge and slimpod rush, produce a heavy crop 

 of forage in most years in the wet swale bottoms. Mediterranean barley 

 makes a heavy growth on the drier swale borders; foxtail fescue, which 

 dries a little earlier, also produces considerable herbage on this site. 



Some large swale areas can be fenced; but if this is not practical, many 

 foothill ranches will be able to defer use of entire range units that contain 

 a high percentage of swale sites. Such lands also usually contain the 

 sites that support the best growth of Spanish-clover and other late- 

 maturing slope species. Because of the relatively high production of 

 swales, it should be beneficial to defer even small acreages in order to 

 provide some additional green forage at the end of the green-forage 

 season. 



The practice of deferring swales has other advantages, too. Cattle 

 can select the choice forage species and have an improved diet when 

 turned into such deferred range pastures. Thus, even when experimental 

 herds were moved from grazing-intensity pastures to ungrazed range 

 in August, crude protein in their diet increased for a short time after the 

 move (12). Also, deferring swales until the soil is no longer soft should 

 reduce soil compaction and increase herbage production. 



Several consecutive years of less-than-average precipitation, however, 

 may greatly reduce the extent to which the green-forage season can be 

 lengthened by deferring grazing in swales. The accumulative effect 

 from a shortage of soil moisture in swales is a decrease in production of 

 late-maturing species. This change was observed in 1947, after low 

 rainfall in 1946 and 1947, and was very pronounced in 1948, another dry 

 year. The clover and the rush portions of the total swale production 

 in pasture 2 had each dropped from about 10 percent, as an average for 

 3 years (1943-45), to about 1.5 percent for each in 1948. Yield of clover 

 dropped from 488 to 32 pounds per acre, and yield of rushes from 442 

 to 33 pounds per acre. Deferring use of swales, however, may be desirable 

 during a period of several dry years since even a small increase of green 

 forage is especially helpful under such conditions. 



Still another way to lengthen the green-forage period is to promote 

 earlier fall and winter growth of the annual plants. This can be done 

 by grazing management that leaves sufficient unused herbage on the 

 grounb, as is shown later by results of grazing-intensity tests. On con- 

 servatively stocked range, green forage will become adequate 2 to 6 

 weeks earlier than on heavily stocked range. 



ADJUSTING RANCH STOCKING TO HERBAGE 

 PRODUCTION 



Each ranch contains range land with different characteristics of soil, 

 topography, brush cover, and rockiness. These characteristics influence 

 not only time of forage growth, but also total herbage production. More- 

 over, production of annual-plant species varies considerably from year 

 to year because of differences in weather. By a skillful adjustment of 



