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TheImprovement ofTropical and Subtropical Rangelands

TheImprovement ofTropical and Subtropical Rangelands

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GRAZING MANAGEMENT 133<br />

The success of year-long continuous grazing in perennial plant communities<br />

is further enhanced because grazing is light during the<br />

growing season, <strong>and</strong> lighter stocking per unit area means leIS soil<br />

compaction by livestock when the soil is wet.<br />

Some of these same reasons could also be attributed to rotational<br />

schemes. Under rotation systeIl18 of grazing on perennial rangel<strong>and</strong>s,<br />

units have sustained increased numbers of livestock <strong>and</strong> have shown<br />

greater improvements in range condition than have units grazed<br />

continuously on a year-long basis at various stocking rates. An advantage<br />

of deferred rotation is the infrequency of livestock movement<br />

required. Under the system, livestock must adjust to the new forage<br />

of each grazing unit only once every grazing season.<br />

A rotation system using as many as 16 units, each grazed 2<br />

weeks or less by 1 or 2 herds, has been studied in South Africa<br />

<strong>and</strong> Zimbabwe. Livestock are not moved at any set time, nor are<br />

the units necessarily stocked in sequence. When plants are growing<br />

rapidly, the livestock are moved frequently, perhaps as often as every<br />

5 days, to prevent injury to plants. When the plants are dormant,<br />

livestock movement is determined by the nutritional requirements of<br />

the animals.<br />

An evaluation of grazing systeIl18 in southem Africa concluded<br />

that the following principles are important:<br />

• Slow rotation systeIl18 do not eliminate selective grazing.<br />

• In a 16-unit, high-intensity, low-frequency system, 12 units<br />

are grued once for about a 2-week period every 6 months, <strong>and</strong> the 4<br />

other units can be used as reBerve grazing in dry years or given a full<br />

year's rest in years of average precipitation.<br />

• High-intensity, low-frequency grazing is designed primarily to<br />

combine sufficient reet with efficient use to permit rapid restoration<br />

of denuded rangel<strong>and</strong>s. There is less advantage to using this system<br />

on rangel<strong>and</strong>s in good condition.<br />

• Range restoration may be retarded <strong>and</strong> greater abuse may<br />

occur if stocking increases more rapidly than indicated by herbage<br />

production.<br />

• With variable precipitation, no system can eliminate Belective<br />

gruing if Bet gruing periods <strong>and</strong> stocking rates are maintained, but<br />

high-intensity, low-frequency grazing reduces selective grazing.<br />

• High-intensity, low-frequency grazing, becauBe it is an intensive<br />

system, may require more labor, fencing, <strong>and</strong> water development,<br />

[ 1.)ltIZ ,d byCoogIe

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