Monday, November 5, 2007
47-3

Balancing Water Scarcity and Growing Demands in Agriculture.

Rick Bottoms1, Khaled Bali2, and Juan Guerrero2. (1) University of California-Davis, Univ. of CA Desert Res & Ext. Cntr, 1004 E. Holton Rd., El Centro, CA 92243, (2) Desert Res & Ext Cntr, University of California, 1050 E. Holton Rd, Holtville, CA 92250

Agricultural-urban water transfer agreements between Imperial Irrigation District and San Diego County Water Authority and Metropolitan Water District of Southern California call for the transfer of nearly 370 million cubic meter of water annually from the Imperial Valley to Southern California. Most of the water available for transfer must come from on-farm water conservation programs and new and improved methods to increase water use efficiency. California dairies have traditionally depended on 80,940 hectares of annually grown forage hay for dairy consumption from the Imperial Valley. In excess of 1 billion cubic meter of water are used to meet the crop water requirements of forages grown in the Imperial Valley. In this study, we introduced alternative forages such as sorghums which are drought and heat tolerant using 25-30% less water per crop season than traditional forages grown in the Valley. Recently, the BMR gene has been introduced into sorghum allowing for the possibility of even better water use efficiency than the traditional varieties. A sorghum grown for silage would use approximately 0.49 ha-m/ha of water to produce a comparable amount of corn silage. This study evaluates the water use efficiency and the impact of deficit irrigation on corn silage, triticale, and sorghum including BMR varieties and measures crop growth factors necessary for high quality forages in California. Normal and deficit irrigation practices ranging from 75% to 100% of crop water requirements were implemented on corn, triticale, sorghum and canola. Crop growth, dry weight, yield, sugar/starch content, and water use efficiency for each treatment were evaluated. Preliminary results indicate that the water use efficiency of the alternatives forages introduced in this study is higher than the traditional forages of the Imperial Valley. Implementation of water conservation practices may include the production of these new forages to meet the water savings objectives.