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Enhancing water productivity for sustainable crop production and water savings represents a major challenge for agricultural water management. Pot experiments under open field conditions were conducted for two years, 2016 and 2017, to assess the effects of regulated deficit irrigation under mulch on onion crop production, following a 2 × 3 factorial experiment with two soil cover systems (wheat straw mulch and no-mulch) and three irrigation levels (100%, 80%, and 60% of crop evapotranspiration), with six replications.The results indicated that onion plants were responsive to straw mulching. Bulb diameter, total yield, dry matter, and water productivity were significantly enhanced under mulch whatever the irrigation level used. The seasonal crop water requirements also considerably decreased (about 33%). The results also showed the sensitivity of onion to water stress. Yield, dry matter, and water productivity were higher under full irrigation compared to the deficit irrigation. However, when mulch was used, regulated deficit irrigation highly significantly improved water productivity and onion crop quality and quantity; and this approach could be a promising management practice to meet water shortage consequences in the dry Mediterranean region.

Basal Stem Rot (BSR) is a disease caused by fungus which affect oil palm tree. This study aims to visualize the geographical distribution of BSR incidence among oil palm smallholders in Selangor using Geographical Information System (GIS) and its relationship to the type of soil series. The geographical distribution of BSR incidence of smallholders in Selangor were mapped using 168 Global Positioning System (GPS) coordinate of possible infected area. The methodology followed in finding the relationship between BSR and soil series by assigning percentage of BSR incidence based on type of soil series. Majority of the BSR incidences were found to be confined to the Selangor-Kangkong (Aeric Tropic Fluvaquent-Typic sulfuric tropic fluvaquent) soil series followed on Peat (Typic Fibric Tropohemist) soil then Kranji (Typic Sulfaquents) soil series and finally the Briah-Organic Clay and Muck (Typic Tropic Fluvaquent) soil series. Distribution pattern of the BSR revealed that most of the incidences were confined along the coastal area which might be due to the planting of oil palm in previous coconut stands. Low pH of Selangor (Aeric Tropic Fluvaquent) and Peat (Typic Fibric Tropohemist) soil series shows a higher BSR incidence while high pH of Kranji (Typic Sulfaquents) and Briah (Typic Tropic Fluvaquent) soil series shows slightly lower BSR incidence. From this study, it can be concluded that the distribution of BSR were mostly confined to the coastal areas which might be due to the planting of oil palm in previous coconut stands rather than any relationship with the type of soil series. This distribution map of BSR incidence can be used to deliver effective extension services regarding BSR to smallholders with a specified target based on location and soil series.

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.

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