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" Field trials show the fertilizer value of nitrogen in irrigation water "
Cahn, Michael; Smith, Richard; Murphy, Laura; Hartz, Tim
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AL
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| Record Number
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945025
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LA31w9n70h
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| Language of Document
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English
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| Main Entry
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Cahn, Michael; Smith, Richard; Murphy, Laura; Hartz, Tim
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| Title & Author
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Field trials show the fertilizer value of nitrogen in irrigation water [Article]\ Cahn, Michael; Smith, Richard; Murphy, Laura; Hartz, Tim
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| Title of Periodical
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California Agriculture
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| Volume/ Issue Number
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71/2
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| Date
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2017
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| Abstract
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Increased regulatory activity designed to protect groundwater from degradation by nitrate-nitrogen (NO<sub>3</sub>-N) is focusing attention on the efficiency of agricultural use of nitrogen (N). One area drawing scrutiny is the way in which growers consider the NO<sub>3</sub>-N concentration of irrigation water when determining N fertilizer rates. Four drip-irrigated field studies were conducted in the Salinas Valley evaluating the impact of irrigation water NO<sub>3</sub>-N concentration and irrigation efficiency on the N uptake efficiency of lettuce and broccoli crops. Irrigation with water NO<sub>3</sub>-N concentrations from 2 to 45 milligrams per liter were compared with periodic fertigation of N fertilizer. The effect of irrigation efficiency was determined by comparing an efficient (110% to 120% of crop evapotranspiration, ET<sub>c</sub>) and an inefficient (160% to 200% of ET<sub>c</sub>) irrigation treatment. Across these trials, NO<sub>3</sub>-N from irrigation water was at least as efficiently used as fertilizer N; the uptake efficiency of irrigation water NO<sub>3</sub>-N averaged approximately 80%, and it was not affected by NO<sub>3</sub>-N concentration or irrigation efficiency.
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