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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #199602
Title: Comparison of site-specific and conventional uniform irrigation management on potatoes

Author
item King, Bradley - Brad
item STARK, J - UNIVERSITY OF IDAHO
item WALL, R - UNIVERSITY OF IDAHOI

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2006
Publication Date: 10/23/2006
Citation: King, B.A., Stark, J.C., Wall, R.W. 2006. Comparison of site-specific and conventional uniform irrigation management on potatoes. Applied Engineering in Agriculture. 22(5):677-688.

Interpretive Summary: Conventional Uniform Irrigation Management (CUIM) assumes uniform fields and uniform water application. Neither of which are true in practice. Site-Specific Irrigation Management (SSIM) which can be defined as irrigation management (depth, timing) based on crop need to defined sub-areas of a field may be needed because of field spatial variability in infiltration, drainage, and runoff of irrigation and precipitation. Crop vigor can vary due to spatially variable nutrient and/or water availability, salinity, pest intensity and plant density, all of which can affect crop evapotranspiration. The existence of spatially variable irrigation requirements under uniform irrigation management means that optimum irrigation scheduling on the field scale is not achievable, resulting in less than maximum water and nutrient use efficiency. This realization along with the desire for site-specific water management to compliment commercial success of other site-specific management technologies has created interest in site-specific irrigation. Implementation of SSIM will require additional irrigation system hardware, labor and information on soil and/or plant water status in each management zone. Costs associated with these additional requirements will need to be offset by increased receipts from improved crop yield and quality in order for the technology to be adopted by producers. A two-year field study was conducted to evaluate the potential for SSIM to increase yield and quality of potatoes relative to CUIM. Near real-time soil water content was used to schedule irrigations under both irrigation management treatments. Field average water application was nearly equal for both irrigation management treatments. In both study years, tuber yield distributions trended 4% greater under site-specific irrigation management but were not significantly different (p<0.05). Total tuber yield per unit of water applied from irrigation and precipitation was 4% greater in 2001 and 6% greater in 2002 under SSIM. Based on a local tuber quality adjusted potato processing contract price structure, the trend in gross income averaged across the field site was $159/ha ($65/ac) greater with SSIM. This increase in gross income is likely about half the actual cost of commercial site-specific irrigation technology. The required 3-5 year crop rotation for potato disease management means that the site-specific irrigation system needs to be mobile or an economic benefit must also be realized from other crops in the rotation. The economic benefit of SSIM needs to be increased or realized for other crops in the rotation for it to be an economically viable technology in potato production systems in Idaho. The results from this study also indicate that available water holding capacity of the soil may not be the best or only parameter to consider in delineating irrigation management zones. A systems approach to SSIM will likely be required that takes into account all known factors affecting yield and include them in delineating irrigation management zones and SSIM decisions.

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