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Abstract.

Enhancing water use efficiency is paramount for sustainable intensification of crop production, but irrigation systems for small-plot research often cannot provide the precision needed to meet the objectives. A surface drip irrigation system was developed to meet the requirements of a study conducted on a sandy loam soil at Becker, MN, USA in 2013. The objective was to compare the performance of two maize (Zea mays L.) hybrids with three levels of nitrogen fertilization under well-watered conditions and two levels of simulated drought stress. Three experimental fields, each with a different previous crop, were equipped with identically designed surface drip irrigation systems, configured to support the randomized block experimental design with four replications. Plots were 6.1 m (eight maize rows) wide and 12.2 m long, using 16 lines of drip tape with an application capacity of 10 mm h^-1, matching the water infiltration capacity of the soil at this site. Drip tape was 0.254 mm thick, with emitter spacing of 152 mm and a flow rate of 0.63 L h^-1. Water was filtered through 106 µm screen filters. Water application was controlled using volumetric automatic shut-off valves with precision of ±1 mm ha^-1 (378 L) and was measured by disc water meters with 2 L accuracy. Water was successfully applied at 3 to 30 mm ha^-1 with the desired precision of ±1 mm ha^-1 per application. This drip irrigation system provides the theoretical basis enabling drought simulation in small-plot experiments for sustainable intensification of crop production.