A field experiment was conducted to study the effect of water regime (W), row spacing (RS) and plant density (D) on growth and productivity of tomato cv. ’Pito Pride’ at the Agriculture Experimental Station of King Abdulaziz University. Two water regimes, W1 (70% of water requirement) and W2 (full water requirement) were studied. Under each water regime three row spacings (RS1, RS2, RS3) and two plant densities D1 (single plant per dripper) and D2 (two plants per dripper) were investigated. Results revealed that W1 reduced number of days to flowering and fruit setting, plant height, plant fresh weight and total yield, while it increased water productivity (WP). Decreasing RS increased water supply and total yield but decreased growth characteristics. D2 increased total yield by 122–168% and WP by 131–180% compared to D1. Interaction between the three variables investigated was significant for all assessed characteristics except fruit yield per plant, total fruit yield and WP. These characteristics were affected by the interaction between RS and D. The highest total yield and WP were obtained from the RS2-D2 treatment. This treatment increased total yield per ha by 11–331%andWP by 12–300% compared with the maximum and minimum yield of other investigated treatments of both seasons. Copyright © 2014 John Wiley & Sons, Ltd.

A field experiment was conducted at Agriculture Experimental Research Station of King Abdulaziz University (KAU), Hada Alsham, Saudi Arabia, for two growing seasons to study the effect of different soil amendments on growth traits and yield of barley crop grown under dry land conditions. Two irrigation treatments using sprinkler irrigation method were studied, full irrigation level, (100% of required water) and minimum irrigation level (60% of full level). Under each irrigation level two soil amendments, humic acid (Ha) with a rate of 10 kg ha-1 and Gel Polymer (Gp) with a rate of 16 kg ha-1 beside the control (not amended) were investigated. Irrigation event was every two days in full irrigation level and every 4 days in minimum irrigation level. Results revealed that, full irrigation level was better than minimum one in most investigated characteristics. The barley growth and yield components increased with application of humic acid and gel polymers amendments compared to control.The best results obtained from humic acid treatment. Irrigation water use was improved under minimum irrigation level and with Ha treatment. Full irrigation level and amendment treatments increased N content in grains. On the basis of the present experiment 10 kg ha-1 and full irrigating are recommended for barley growth and yield. When water is a limited factor for agriculture production, minimum irrigation level is recommended to use because it saves 40% of irrigation water with minimal yield reduction.

Due to its scarcity, wastewater reuse has become an essential element in water resources and agriculture planning and management in arid regions. This research aimed to study the effect of irrigation with diluted wastewater on the yield, water use efficiency (WUE), fecal coliform bacteria count, and toxic metals in relation to the root and the fruit of okra and eggplant crops under surface and subsurface drip irrigation systems. A strip plot design (split block) was used in field crop experiments carried out over two consecutive seasons (2011 and 2012) at an agriculture research station in the Western region of Saudi Arabia. The main plot treatments contained six wastewater qualities and two irrigation systems arranged in strips with subplots of 2 × 3 m each. The results showed no significant difference between the two irrigation systems on the fruit yield/ha and WUE of okra, while in eggplant, the subsurface irrigation showed a significant difference. On the other hand, the root toxic metal (Cd, Cr, Ni, and Pb) concentrations of both crops were significantly higher under the surface irrigation. Conversely, there was no significant difference of toxic metals in fruit under the two irrigation systems, yet the number of fecal coliform bacteria was affected noticeably under the two irrigation systems in both crops. In general, as the percentage of wastewater in the irrigation water increases, the number of bacteria and the concentration of toxic metals increase. However, the rate of increase varies among the six water qualities. More importantly, all detected metal concentrations were less than the cytotoxic concentrations according to WHO/FAO standards.

Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural site in the western region of Saudi Arabia, to study the effect of wastewater irrigation on the yield, toxic metals, and fecal coliform bacteria of white radish crop. Six different wastewater qualities were prepared by diluting various percentages of the treatment plant’s effluent with local groundwater (LGW). The crop water requirement for white radish was calculated by Penman-Monteith equation for dry land condition and supplied daily by two drip irrigation systems; surface and subsurface. Root yield, irrigation water use efficiency (IWUE), fecal coliform, and content of toxic metals in the plant and soil were determined at the end of each growing season. Results indicated that the highest root yield/ha, and IWUE were obtained from the treatments of 60T (60% wastewater mixed with 40% LGW) and 100T (100% wastewater). Due to the relatively early cultivation in the second growing season, the total yield/ ha and IWUE were higher than that of the first season.On the other hand, fecal coliform bacteria count and toxic metals increased systematically in the plant and soil as the quantity of wastewater in the irrigation water increased. Notably, the concentrations of toxic metals in the plant and soil were less than that of the cytotoxic standards declared by WHO-FAO (2007) and EU (2002). In conclusion, the best treatments that produced the highest yield and IWUE with minimal microbial contamination were 60T and 100T suggesting a safer use, better performance and considerable LGW conservation.

A field experiment was carried-out at Agriculture Experimental Station of King Abdulaziz University (KAU), Hada Alsham, Saudi Arabia, to evaluate the changes in some physical and fertility properties of soil treated with humic acid and/or gel polymers in relation to those of untreated soil under two water regimes. Full irrigation level, (100% of required water) and minimum irrigation level (60% of full level). Under each irrigation level two soil amendments, humic acid with a rate of 10 kg ha-1 and gel Polymer with a rate of 16 kg ha-1 beside the control (not amended) were investigated. The experimental site was cultivated by barley for two growing Seasons using sprinkler system for irrigation. Results indicated that using soil amendments enhanced soil physical and fertility properties. They decreased soil bulk density and saturated hydraulic conductivity while increased water holding capacity, soil organic matter and soil nutrients under both irrigation level. The enhancement under minimum irrigation level was better that that of fully irrigation level. Ha treatment was better than Gp treatment. Therefore, using humic acid with a rate of 10 kg ha-1 with minimum irrigation is good option to enhance the important physical and fertility properties of light textured soils under dry land conditions.

Potassium (K) is a critical element for date palm production especially under stress conditions. During 2011 and 2012 seasons, two methods of K fertilization (K2SO4, 52% K2O) at different rates were evaluated on ‘Seweda’ date palm cultivar. The first method was soil broadcast (SB) of 2, 3 and 4 kg/palm in 3 equal doses (February, April and May). While in the second method, half of these amounts were applied as SB and the other half as foliar spray (FS) in 10 equal doses during growing season. The results showed no significant effect of K fertilization on either bunch weight or yield as the mean of two seasons. However, in 2012, the highest bunch weight and yield was at the 2 kg SB + 2 kg FS treatment while, the lowest values were at the 2 kg SB treatment. The highest rutab % obtained from the 2 kg SB treatment. Both fruit and flesh weight at the bisir stage were higher at the high rates of K applied as SB + FS than SB. Also, K concentration of leaves was higher in SB + FS than SB. K had no clear effect on chlorophylls, however, the highest Chl a/Chl b ratio was at the 2 kg SB + 2 kg FS treatment. Most of physical and biochemical characteristics of fruit showed unclear response to K fertilization. In fruit, N concentration was lower at the high rates of K applied as SB + FS than SB. At the same K fertilization rate, both N and K concentration in the soil were higher at SB than SB + FS treatments. Potassium fertilization especially at 4 kg K2SO4/palm/year (2 kg SB + 2 kg FS) is recommended for ‘Seweda’ dates.

A field experiment was conducted in the western part of Saudi Arabia to optimize irrigation water use (IWU), yields and quality of the ’Nabbut-Saif’ date palm grown in sandy loam soil under arid conditions. Four water regimes were investigated. The supplied amounts of irrigation water were 50, 65, 82 and 100% of date palm water requirements to the first (W1), second (W2), third (W3) and fourth (W4) water regimes, respectively. The daily water requirement was calculated using the Penman– Montieth equation for dry climates and applied to the trees three times a week through a drip irrigation system. Results indicated that giving 65% of total date palm water requirement maximized date yield by producing 46.1 kg per tree and resulted in the best IWU (0.8 m3 kg
1 per tree). Increasing the water regime to 82 and 100% of total water requirement produced only 45.5 and 46 kg per tree respectively and reduced IWU. Generally, fruit quality characteristics were insignificantly affected by the water regimes investigated. The results suggested that supplying 34 m3 yr
1 per tree for date palms grown under the conditions of the western part of Saudi Arabia is enough to maximize IWU, yield and quality of the ’Nabbut-Saif’ date palm cultivar. Copyright © 2014 John Wiley & Sons, Ltd.

The main aim of this research is to improve the squash yield and quality using sulphur and pozzolan as soil conditioners in Saudi Arabia. This experiment conducted during winter and spring (2012 and 2013). A split split plot design with 3 irrigation water salinity levels (IWSL) (1200, 3000, and 6000 mg/l), 4 pozzolan placements (PP) (surface, 10 cm depth, 20 cm depth, and control), 3 sulphur doses (SD) (0, 4, 6 ton/ha), and 3 treatments was used. Applied PP in the soil surface and SD 6 ton/ha under IWSL 1200 mg/l increased plant height (77.57 and 72.80%) number of leaves/plant (38.21 and 31.45 leaves), fruit setting (42.54 and 40.24%), fruit yield (23.17 and 20.53 ton/ha), and water use efficiency (294.90 and 258.79 kg/mm/ha) respectively in the winter and spring compared with the control (no pozzolan, no sulphur and IWSL 6000 mg/l).

Irrigation with wastewater is a widespread observable fact in developing countries, especially those exhibiting arid climate conditions. Utilization of large volumes of domestic wastewater effluent is part of an overall integrated water resources management. The objective of this study was to investigate the effect of irrigation by six different treated domestic wastewater qualities on the yield of Cabbage and Lettuce crops under surface and Sub-surface drip irrigation systems. Field experiments were carried out during 2011 and 2012 seasons at the Agriculture Research station of King Abdulaziz University located at Hada Alsham area north east of Jeddah city. The six water qualities were prepared by diluting treated wastewater with local groundwater of the region. The dilution percentages were 0%, 20%, 40%, 60%, 80%, and 100% treated wastewater. Crop water requirement were calculated based of Penman Monteith equation for dry land condition and supplied daily to the crops. The obtained results showed significant impact of wastewater quality and irrigation system and their interactions on vegetative yield and yield components of both crops. Irrigation with 60% and 80% wastewater under sub-surface irrigation system produced the highest yield and yield components in both seasons. Irrigation Water Use Efficiency (IWUE) of cabbage crop increased under the use of subsurface drip irrigation while IWUE of lettuce crop increased under surface drip irrigation system. Among dilution percentages, the 60% gave the highest IWUE in both crops. In conclusion, this study implies an advantage of using treated wastewater in growing vegetable crops. This in turn saves considerable quantities of local groundwater resource.

A field experiment was conducted for evaluating the effect of brackish water on citrus growth and soil chemical properties during 2008-2009. For the study, one-year-old citrus seedlings were transplanted and were drip irrigated with two types of brackish (saline) water. One with high salinity (SW) having an electrical conductivity (ECi) of 7.16 dS/m. The other with low salinity (GW) having ECi of 1.36 dS/m. Results of the study revealed that, only 14% of the total transplanted seedlings were succeeded with limited growth under SW compared to 82% with increased growth parameters under GW. Results of soil properties revealed accumulation of salts at the fringe of the irrigated area under the emitter in both irrigation waters, but the phenomenon was largely accelerated under SW. Frequent irrigation with saline water increased the accumulation of Na and Cl which decline soil chemical propertied, cause nutrients imbalance and increase toxicity, consequently plant damage.