**Pavel Trifonov, Naftali Lazarovitch and Gilboa Arye \***

French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 84990, Israel; paveltri@post.bgu.ac.il (P.T.); lazarovi@bgu.ac.il (N.L.)

**\*** Correspondence: aryeg@bgu.ac.il

Received: 3 July 2018; Accepted: 21 July 2018; Published: 24 July 2018

**Abstract:** Narrow profit margins, resource conservation issues and environmental concerns are the main driving forces to improve fertilizer uptake, especially for potatoes. Potatoes are a high value crop with a shallow, inefficient root system and high fertilizer rate requirements. Of all essential nutrients, nitrogen (N) is often limiting to potato production. A major concern in potato production is to minimize N leaching from the root zone. Therefore, the main objective of this study was to examine the potato crop characteristics under drip irrigation with low-discharge (0.6 L h<sup>−</sup>1) and to determine the optimal combination of irrigation (40, 60, 80, and 100%) and fertigation (0, 50, and 100%) doses. In this study, the 80% (438.6 mm) irrigation dose and a 50% (50 mg N L−1) fertigation dose (W80%F50%) showed that these doses are sufficient for optimal potato yield (about 40 ton ha−1) in conjunction with water and fertilizer savings. Moreover, this treatment did not exhibit any qualitative changes in the potato tuber compared to the 100% treatments. When considering water productivity and yield, one may select a harsher irrigation regime if the available agricultural soils are not a limiting factor. Thus, higher yields can be obtained with lower irrigation and fertigation doses and a larger area.

**Keywords:** water productivity; nitrogen productivity; fertigation; drip irrigation; low-discharge; arid regions
