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Due to the environmental changes, especially global warming, water scarcity will be more serious in the water shortage areas. Efficient and judicious husbandry of the limited water resources is very important. Usually irrigation water is applied considering only the plant water need whereas the impact of the excess water on the soil air O2 is ignored. Applied water fills the soil pores, replaces the soil air and reduces the amount of soil air O2. Lack of or insufficient soil air O2 reduce root growth, nutrients availability and photosynthesis rate, result in sever reduction in crop yield. The study was conducted in a greenhouse at the Okinawa Subtropical Station, JIRCAS. Five wooden boxes (180cmX90cmX30cm) were connected with each other. Six galvanized batteries along with a T-type thermocouple, was set at the entrance of the first box and at the end of the each box. Nine tomato (var. First Power) seedlings were transplanted in each box on February 18, 2005, and grown as a normal crop. At the flowering stage, soil surface in the boxes was covered by white polyethylene sheets and closed tightly to stop entry of air into the soil through the soil surface. Tomato was irrigated as and when required with a PVC pipe inserted in the surface of the boxes. We successfully developed a soil air O2 creation technique connecting wooden boxes with each other and in situ soil air O2 measurement using the galvanized battery. The results revealed that the amount of soil air O2 gradually reduced from the first box to the last one. The available soil air O2 concentration in the first box was 20.1% while it was 12.8 % in the last box. Due to the reduction in soil air O2, chlorophyll content and root dry matter were drastically reduced causing reduction of tomato yield from 2 to 18%. The tomato yield was 28.5 ton/ha in the first box, while 23.4 ton/ha in the last box. The seasonal mean soil air O2 indicated that by decreasing the available soil air O2 content by 1%, the tomato yield would reduce by 0.88 t/ha. Therefore, consideration of the balance between soil air O2 and soil water while deciding amount of irrigation water may increase crop yield, water savings and water use efficiency.

Production of vegetable crops under calcareous soil faced many problems, such as soil salinity and sodicity. Three sulphur amendment levels (SAL) with (0 (control), 4, and 6 ton/ha) was applicated to study its effect on reclamation of this soil and produce squash crop during 2 successive seasons of winter and spring (2012-2013). The contents of soil nitrogen (N), phosphorus (P), potassium (K), pH, electric conductivity (EC), and organic matter (OM) in 2 soil depths ((0-15) cm and (15-30) cm) was measured as the efficacy parameters of the soil reclamation. The results indicated that SAL 6 ton/ha gave the best results and significantly decreased soil EC (57.54% and 51.51%) and pH (4.67% and 2.83%) respectively in (0-15) and (15-30) cm soil depth compared with the control. Moreover, the contents of N, P, K, and OM of the soil increased (16.0% and 68.50%), (29.20% and 26.29%), (14.61% and 15.85%), and (3.99% and 7.60%) respectively in (0-15) and (15-30) cm soil depth. These results affected in increasing of squash yield significantly 9.39 ton/ha in winter and 6.11 ton/ha in spring.

An experiment was conducted in indoor lysimeters to study the effect of deficit irrigation on water use efficiency and bird pepper (Capsicum annuum L.) production under drip irrigation system. Six-week-old seedlings were transplanted into each lysimeter in the first of July, 2004. Four seedlings were grown in each lysimeter. Three irrigation treatments were investigated. The first treatment (W1) was 100% of the field capacity as a control. The second and third treatments (W2 and W3) were giving 85% and 70% of the field capacity, respectively, as deficit irrigation treatments. The deficit irrigation practice was applied after 15 days of the transplanting and continued for the whole growth season. The results indicated that the highest yield was obtained from W1 which grown under no stress. Deficit irrigation tends to increase water use efficiency and decrease the fresh fruit yield. Giving 85 % of the field capacity (W2) led to save 41% of the irrigation water and reduce the total yield by 29 %. Giving 70% of the field capacity (W3) resulted in 85 % of irrigation water saving but 40% of the total yield was lost. . In conclusion, water deficit is a practical technique to save large amounts of water.

A field experiment was carried-out at the Agriculture Experimental Station of King Abdulaziz University located at Hada Alsham, 110 km north east of Jeddah, to optimize the productivity and irrigation water use efficiency of pearl millets (Pennisetum glaucum L.), as green fodder under different irrigation methods and stress. Five treatments were investigated in this study: three with full irrigation requirements including sprinkler irrigation (SPI), drip irrigation (DI) and sub-surface drip irrigation (SDI), the remaining two treatments were stress treatment namely: sub-surface drip kept at 85% of field capacity (SDI 1) and sub-surface drip kept at 70% of field capacity (SDI 2). Irrigation water for all treatments was precisely supplied using water electronics module (WEM). Results indicated that SDI treatment gave the highest fresh and dry biomass, followed by SDI 1 compared to other treatments. Increasing number of cuts sharply decreased biomass production. Increasing water stress decreased biomass production but SDI with water stress increased biomass production compared to SPI with full irrigation requirement. Irrigation water use efficiency (IWUE) was decreased by increasing water stress and number of cuts. Results also proved that WEM is a practical tool to precisely supply irrigation water when needed, and can be effectively used to precisely control water stress.

A field experiment carried-out in sandy loam soil to study the effect of effective microorganisms and green manure on productivity of two forage crops under dry conditions. The experiment was conducted at Agriculture Experimental Station of King Abdulaziz University (KAU) located at Hada Alsham, north east of Jeddah, KSA. Four treatments were investigated under the current study. In control (T1) the two grown crops were growing using recommended dose of nitrogen fertilizers added after planting. The second treatment (T2) was diluted solution (1:1000) of effective microorganisms (EM1). The third treatment (T3) was green manure while the fourth treatment (T4) was EM1 and green manure together. The results indicated that the best treatments were green manure with EM1 (T4) in alfalfa while it was only green manure (T3) in pearl millet. The single effect of EM1 was positive but not significant compared with control. Water use efficiency increased by using green manure and effective microorganisms. Increasing water use efficiency resulted in large amount of irrigation water saving. The saved water reached to 24% in pearl millet and 17% in alfalfa compared to control.

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A field experiment comparing different irrigation methods (Sprinkler Irrigation “SPI”, surface drip “DI” and sub-surface drip “SDI) were precisely controlled for alfalfa productivity and water use efficiency. The experiment was conducted at the Agricultural Experimental Station of King Abdel-Aziz University. The design of the experiment was Randomized Complete Block Design (RCBD) with four replicates, consists of three irrigation method. Water Electronics Module (WEM) technology was used to fully controlled the irrigation methods. The results revealed SDI increase growth parameters (plant length, number of tillers and leave to stem ratio) compared with DI and SPI. The least water supply was recorded in SDI followed by DI and SPI respectively while the highest IWUE obtained from SDI followed by DI and the least IWUE was recorded in SPI. SDI and DI saved 35.7% and 29.2% of irrigation water compared with SPI. In spite of decreasing water supply under SDI and DI high dry yield was obtained. The increase in dry yield was 45% in SDI and 15.9% in DI compared with SPI. The results of experiment especially soil moisture data proved that WEM is a practical tool to precisely supplied irrigation water when needed and can be recommended for efficiently controlled different automated irrigation systems.