Accumulation of high level of nitrate (NO3−) in leaves is a serious issue for vegetable crops like lettuce (Lactuca sativa L.). Therefore, this study aimed to limit NO3− level by adjusting the balance between fertilization and irrigation program in lettuce. In a strip plot design with three replicates, lettuce plants were grown under four fertilizer treatments and three irrigation regimes. Three organic fertilizers (biochar, compost and vermicompost), in addition to mineral fertilizer, were used. The irrigation regimes were 60, 80 and 100% of crop evapotranspiration, ETc (ETc60, ETc80, and ETc100). Nitrogen (N), phosphorus (P) potassium (K) and organic matter (OM) in soil as well as yield, N, P, K and NO3− of lettuce were estimated. Findings showed that vermicompost or biochar (with any irrigation regime) as well as compost with irrigation by ETc60 were the effective combinations for increasing K content in soil after harvest. Under irrigation by ETc80 or ETc100, vermicompost or biochar were the efficient treatments for increasing lettuce yield equaling the farmer common practice (ETc100 x mineral fertilizer). Under irrigation by ETc60, mineral fertilizer or vermicompost showed the highest lettuce leaf content of K. Moreover, ETc60 or ETc80 x mineral fertilizer recorded the maximum NO3− content of lettuce leaves. The accumulation of nitrate in lettuce leaves owing to mineral fertilizer reached about 1.24 times than that of organic fertilizers. Compost x ETc80 or ETc100 showed the minimal NO3–N accumulation, hence, high relative reductions in NO3–N accumulation as compared to the common practice (ETc100 x mineral fertilizer) were observed. In conclusion, irrigation by 80% instead of 100% of crop evapotranspiration of organically fertilized lettuce (especially with vermicompost) could be adopted since such practice recorded high lettuce productivity with low NO3− content.

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A MAGNETIC device was designed and manufactured to assess the implications of using magnetized saline water for crop irrigation on plant growth parameters and properties of soils grown thereon. To reach this aim, four soil types differing in their textures and contents of soluble salts, were sampled, uniformly packed in PVC columns and then cultivated with wheat grains (Triticum aestivum L.). Two weeks later, plants received one of the following treatments for water irrigation i.e., tap water (0.4 dS m -1 ), magnetized tap water, saline water (7.5 dS m -1 ) and magnetized saline water at a rate of 100% of field capacity (FC) to collect water draining from each column. Significant improvements in both the growth and yield parameters of wheat as well as in the soil chemical properties (i.e. pH, EC e , Na + , Cl -, SAR, available N, P and K contents) occurred due to irrigation with the magnetized saline water compared to irrigation with the non-magnetized saline ones. This magnetized waters seemed to increase the leachability of salts downwards the soil columns. The corresponding increases attained by magnetized saline water were higher than those attained by magnetized tap water. Also, NPK contents increased significantly within the different plant parts owing to magnetizing the irrigation water. Moreover, phosphorus fertilizer use efficiency increased significantly due to the irrigation with the magnetized waters i.e., the saline or the non-saline one compared with those received the non-magnetized waters. In conclusion, magnetizing irrigation water of low quality might reduce its negative implications on the grown plants and minimize accumulation of salts with the surface top soil.