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<br />32
<br />
<br />J.D. RHOADES ET AL.
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<br />Crop Vet I Viw2 Yd. " LF' Accum.5 Accum. Accurn. Accum.
<br /> Y" V.. Ydw LF
<br />"Successive" crop rotation
<br />1982 wheat 655 556 -99 -0.18 655 556 -99 ~0.18
<br />1983 Sugar beeta 1029 1247 218 0.18 1684 1803 119 0.07
<br />1983 melons 427 627 201 0.32 2111 2431 320 0.13
<br />1984 wheat 688 833 145 0.17 2799 3264 465 0.14
<br />1985 Sugar beets 1074 1364 290 0.21 3873 4623 754 0.16
<br />1985 melons 427 345 -81 -0.24 4300 4973 673 0.14
<br />"Block" rotation
<br />1982 cotton 988 1288 300 0.23 988 1288 300 0.23
<br />1983 cotton 1034 1161 127 0.11 2022 2451 429 0.18
<br />1984 wheat 688 798 109 0.14 2710 3249 541 0.17
<br />1985 alfalfa 2062 2057 -5 -0.00 4770 5306 536 0.10
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<br />TABLE 4
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<br />Estimated amounts (mm) of water used in evapotranspiration and-lost as deep percolation
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<br />I Evapotranspiration estimated from pan evaporation and crop factors at Brawley, California.
<br />2Total amount of water applied for irrigation.
<br />3Estimate of deep-percolation drainage water Le., V1W- Vet.
<br />4Estimate of leaching fraction (LF'), i.e., V dw/ V;w.
<br />5 Accumulated over entire experimental period.
<br />
<br />Crop/Year
<br />wheat/1982' sugar beets/1983" cantaloupes/1983'
<br />8.1 (0.1 )6. 9.6(0.2) 439(13)
<br />8.1(0.2) 9.6(004) 430(11)
<br />8.3(0.1 ) 9.2(0.2) 398(16)
<br />wheat/1984' sugar beets/1985' eantaIoup~s/1985'
<br />7.9(0.2) 9.2(0.2) 115(5)
<br />7.8(0.2) 9.2(0.2) 142(8)
<br />8.0(0.2) 8.7(0.2) 139(12)
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<br />TABLE 5
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<br />Yields of crops in "successive" rotation
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<br />. Treatment1
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<br />Ca
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<br />Ie == Colorado River water used solely for irrigation; Alamo River water used in relatively smaller
<br />(Ca) and larger (eA) amounts, after seedling establishment with Colorado River water for wheat
<br />and sugar beets, Cantaloupes only irrigated with Colorado River water.
<br />2TonB of grain per hectare.
<br />3Tons of sugar per hectare.
<br />"Kilograms of seed per hectare.
<br />f>Commercial yield in number of cartons per plot; plot size;;;; 229 X 11.6 m2 =0.26 ha.
<br />6Va\ue in parentheses is standard error of mean; six replicates.
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