No abstract

Due to water scarcity and dry Mediterranean conditions, improving water use efficiency is a major challenge for sustainable crop production and environment protection. Field experiments were conducted for two consecutive years (2010 and 2011) to assess the effects of variety and irrigation method on potato crop, following a 2 × 4 factorial experiment type arranged in a split plot design with two spring potato varieties (Spunta and Marfona), and four irrigation methods (drip irrigation with two modes of dripper spacing/dripper flow: 30 cm at 4 l/h and 60 cm at 8 l/h, sprinkle irrigation, and furrow irrigation), with three replicates. Potato was irrigated when soil moisture in the active root depth was within the range of 75-80% of field capacity as determined by the neutron probe technique. Results did not show any differences between both varieties. Moreover, no differences in marketable yield, total dry matter, and harvest index were found between irrigation methods. However, results showed that sprinkle irrigation significantly enhanced nitrogen use efficiency. Furthermore, both water productivity and irrigation water use efficiency were significantly increased under drip irrigation compared with the other irrigation methods. They were about twice those under furrow irrigation, indicating that the employment of drip irrigation method can effectively address water shortage and sustainable potato production, in the dry Mediterranean region.

Establishing a representative monitoring location of soil water content is important for agricultural water management. One of the challenges is to develop a field protocol for determining such a location with minimum costs. In this paper, we use the concept of time stability in soil water content to examine whether using a short term monitoring period is sufficient to identify a representative site of soil water content and, therefore, irrigation scheduling. Surface moisture-density gauge was used as a means for measuring soil water content. Variations of soil water content in space and time were studied using geostatistical tools. Measuring soil water content was made at 30 locations as nodes of a 6×8 m grid, six times during the growing season. A representative location for average soil water content estimation was allocated at the beginning of a season, and thereafter it was validated. Results indicated that the spatial pattern of soil water content was strongly temporally stable, explained by the relationship between soil water content and fine soil texture. Two field surveys of soil water content, conducted before and after the 1st irrigation, could be sufficient to allocate a representative location of soil water content, and for adequate irrigation scheduling of the whole field. Surface moisture-density gauge was found to be efficient for characterising time stability of soil water content under irrigated field conditions.