Course: BFM 101 Biofuels Fundamentals

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Local Impact

The most intensive drain on water resources for ethanol production will be in areas that rely on irrigation for corn production, and where local aquifers cannot adequately supply processing water for facilities without impacting other local users.  Understanding these regional differences can reduce fears of across-the-board water depletions from biofuel production.  But, it also points out the challenges to sustainable water resources when producing biofuels in regions reliant on irrigation. Much has been done, but further improvements can be made in efficient use of water resources for irrigated corn production.

A recent study in Nebraska pointed out that over a large irrigated region, there was very efficient corn production, but also room for irrigation efficiency improvement.  These improvements include both management and cultural practices, like no-till farming, and more efficient irrigation methods. (see SIDEBAR)

Limited Irrigation

A strategy for saving water on a basin scale is to adopt limited, or deficit irrigation. Applying less than the full crop water needs is called limited or deficit irrigation.  In water-short regions, this practice is being encouraged as a water conservation tool.  If done correctly, limited irrigation can reduce water use without serious economic impact compared to other irrigation conservation practices for the same amount of water savings. Studies have shown that the last few inches of water, above what the plant can use, results in marginal yield gains, at much greater cost and water use per bushel.

Fact Sheet:
Limited Irrigation

Study Shows Corn Production Efficient, Room for Water Efficiency Improvements

“Data on yield, irrigation, and nitrogen fertilizer collected over 3 years (2005-2007) from 777 irrigated corn fields in the Tri-Basin Natural Resources District (NRD) in central Nebraska were used to estimate current yield gaps, irrigation water-use efficiency, and fertilizer N-use efficiency (NUE).  Irrigated corn producers in the Tri-Basin NRD, on average, achieved relatively high corn yields (only 11% below yield potential ceiling) with much greater than average nitrogen use efficiency compared with the US national average,” [7]. There remain considerable opportunities to advance yields and inputs efficiencies by means of pivot instead of surface irrigation. Mean three-year irrigation by surface irrigation was 15.3 inches of water and by pivot irrigation was 9.0 inches of water.  This contrasted with a modeled optimum irrigation (more precise timing and amount applied with crop needs) depth of 8.3 inches and a limited irrigation depth of 7.0 inches.  Changing from surface irrigation to pivot can bring water use very close to the optimum amount.  It was estimated that 32% of the total annual water volume used for irrigated corn production in the study area could be saved by converting all surface irrigation to pivot irrigation and adopting an optimum irrigation strategy [7].rectly, limited irrigation can reduce water use without serious economic impact compared to other irrigation conservation practices for the same amount of water savings. Studies have shown that the last few inches of water, above what the plant can use, results in marginal yield gains, at much greater cost and water use per bushel.

Resources by eXtension, Bioenergy & Sustainability, BIOEN3 CC BY-NC-SA 2.5
www.extension.org/pages/63365/bioenergy-curriculum

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