FOREST AND RANGE RESOURCES OF UTAH 31 



TIME OF YEAR TO BEGIN AND END GRAZING ON A RANGE 



EFFECT OF EARLY GRAZING UPON PLANTS 



Nature has so arranged things that from food stored in seeds, 

 roots, or stems spring growth can well be carried on until the days 

 are warmer and the new leaves have developed enough to make food. 

 Nature, however, did not provide protection against heavy grazing 

 by hungry livestock during this critical period. What happens when 

 a cow or sheep nips off the plant, or a large portion of it, during 

 this early spring period? Much of the stored food has already 

 been used to make the growth which the cow or sheep consumes. 

 Not many, sometimes none, of the leaves are left to make more food. 

 The plant is greatly handicapped and does not recover its normal 

 vigor during the entire summer. At the Intermountain Forest and 

 Range Experiment Station it was found that plants grazed too early 

 produce 25 per cent less growth in a season than plants that are not 

 grazed until they have a good start. One-fourth less forage pro- 

 duced ! This is a great loss to the stockmen and to the people who 

 need the livestock products. 



Where a cow, horse, or sheep walks across moist or wet ground 

 the plants are crushed and broken and the soil is packed as a result 

 of the trampling. The roots of the plants need air. The air enters 

 the soil through the air spaces between the soil particles. When the 

 soil is packed these air spaces are more limited, and air is more or 

 less excluded. Also, any condition that lessens the amount of water 

 in the soil should be avoided if possible, because water is one of the 

 main factors affecting forage production. Water evaporates more 

 rapidly from packed soil, for one reason, because in packed soil 

 there is a continuous passage way from soil particle to soil particle 

 and the soil water can travel to the surface where evaporation is 

 going on. In unpacked soils the air spaces between particles check 

 the current to the surface, and the soil moisture is held more as 

 thin films around the soil particles. For these reasons ranges should 

 not be grazed in the spring while the soil is wet from the melting 

 snow. (Fig. 13.) 



EFFECT OF EARLY GRAZING UPON LIVESTOCK 



Several poisonous plants, especially the larkspurs and death 

 camas, are among the very earliest plants upon the ranges. They 

 make luxuriant growth before many of the other plants are well 

 started. When stock are on the ranges too early, they eat many of 

 these poisonous plants, with fatal results. Poisonous plants are 

 discussed more fully on p. 37. 



During the first period of growth, plants are as much as 85 per 

 cent water. 



A 1,000-poimd animal that is not subjected to work or exercise in procuring 

 his feed, as one maintained in a stall, requires approximately 16 pounds of 

 concentrates and air-dry roughage, such as good hay, every 24 hours as a 

 maintenance ration — that is, a ration ample merely to maintain, not to in- 

 crease, his weight. When the young feed is short, as, for instance, during the 

 first two weeks after growth begins, it is necessary for an animal to travel 

 over a large area to gather the required 80 pounds or so of this succulent 

 leafage or the equivalent of 16 pounds of air-dry hay. Often an animal, 

 especially a cow poorly wintered, can not gather enough of the young growth 



