COMPARISON OF SITE-SPECIFIC AND CONVENTIONAL UNIFORM IRRIGATION MANAGEMENT FOR POTATOES

Abstract

Site-Specific Irrigation Management (SSIM) can be defined as irrigation management (depth, timing) based oncrop need to defined sub-areas of a field referred to as management zones. Implementation of SSIM will require additionalirrigation system hardware, labor, and information on soil and/or plant water status in each management zone. Costsassociated with these additional requirements will need to be offset by increased receipts from improved crop yield and qualityin order for the technology to be adopted by producers. The potential for SSIM to increase crop yield, quality, and economicreturn has not been evaluated in field studies. Crops such as potatoes, for which yield and quality are highly sensitive to soilwater availability, are most likely to show an economic benefit from site-specific irrigation management. A two-year fieldstudy was conducted to evaluate the potential for SSIM to increase yield and quality of potatoes relative to ConventionalUniform Irrigation Management (CUIM). Near real-time soil water content was used to schedule irrigations under bothirrigation management treatments. Field average water application was nearly the same for the irrigation managementtreatments, 503 mm (19.8 in.) in 2001 and 445 mm (17.5 in.) in 2002. In both study years, tuber yield distributions trended4% greater under site-specific irrigation management but were not significantly different (p < 0.05). Total tuber yield perunit of water applied from irrigation and precipitation was 4% greater in 2001 and 6% greater in 2002 under SSIM. Basedon a local tuber quality adjusted potato processing contract price structure, the trend in gross income averaged across thefield site was $159/ha ($65/acre) greater with SSIM. This increase in gross income is likely about half the actual cost ofcommercial site-specific irrigation technology. The required 3- to 5-year crop rotation for potato disease management meansthat the site-specific irrigation system needs to be mobile or an economic benefit must also be realized from other crops inthe rotation. The economic benefit of SSIM needs to be increased or realized for other crops in the rotation for it to be aneconomically viable technology in potato production systems in Idaho.