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Irrigation - Small Acreage - extension.usu.edu Page 2 of 2 <br />open your hand and bounce the ball (in the palm of your hand), the soil remains In a <br />stable shape, your soil has more than 50`yo of its available water holding capacity. If it <br />crumbles, it needs irrigation. <br />Am I applying too much water? Using too much water washes away plant nutrients. <br />When this happens grasses appear yellow. Growth of aquatic weeds, such as sedge or <br />rushes, are also indicators of too much water. <br />What if I'm short on water? If you grass is going dry and dormant between irrigation <br />turns in the hottest past of the summer, it is time to sacrifice some pasture. Let some land <br />dry up in July and August, the grass will green up again in the fall. IN the meantime, keep <br />your most productive areas green and unstressed by focusing your irrigation here. You <br />will get more production from a smaller area of unstressed grass than a larger area of <br />grass going in and out of dormancy. <br />Clow long should I Irrigate? While this depends on the irrigation supply rate, in general, <br />irrigate sandy soils for short periods (9-12 hours). Before considering rain as a <br />replacement for an Irrigation turn, use a shovel to see how deep it has penetrated into the <br />soil. Not often does a rain storm provide enough water to fill the rooting zone. <br />Sprinkling is one of the best ways to efficiently irrigate your pasture, but it requires a <br />significant monetary investment in equipment. There is little runoff with sprinklers and it Is <br />easy to measure how much water is being applied, <br />Flood Irrigation Methods. With all flood Irrigation systems, it is essential that provisions <br />be made to drain excess tail water off the bottom of the field. This water may carry <br />fertilizers and sediment and thus be a source of contamination to streams. <br />Graded Border Irrigation Is when water is flooded down the field between two dikes. It <br />works well, but the land should be leveled for best efficiency. It is difficult to know how <br />much water soaked in and how much ran off the bottom of the field. <br />Corrugations are closely spaced small furrows that carry water from the top of the field to <br />the bottom. This approach doesn t require quite as level a field as border irrigation, but <br />still doesn't provide for easy monitoring of the water actually retained by the soil. It is also <br />very rough running hay harvesting equipment across the corrugations. <br />Wild Flood is just running water from the top of the field to the bottom with no mechanism <br />for insuring an even distribution. For this method to work efficiently, the field must be very <br />level with a uniform fail from top to bottom. <br />Fundamentals of Irrigation <br />K V[4'W' f ?,,,V,P,r?IQil <br />Irrigation Considerations <br />Vew lpint_Ptmw (Size: 4.30 MB) <br />Vie?E_Fq„rmg (Size: 5.7 MB) <br />hvr?ttmaslet Ya1?llf+±t4 rs._`•3' t`-"e ttsact..P.ttix sio esiraz'SsT1 <br />http://cxtension.usu. edu/smac/`htm/in igation 114/2008 <br />60