A field experiment was carried out for two successive winter and summer seasons (2016-2017) at Ismailia Agric. Res. Station in Ismailia Governorate, Egypt using wheat (Triticum sativa cv Giza 168) and peanut (Arachi shypogaea cv Giaz 5) crops to study the effect of organic soil conditioners individually or mixed with synthetic soil conditioners on physical and chemical properties of sandy soil, nutritional status and plant productivity. The experiment was arranged in split plots design with three replicates. Five forms of organic soil conditioners were applied as main plot consists of control (NPK), yeast sludge (YS) at rate of 2 kgfed^-1, commercial humic acids (HA at rate of 1 kgfed^-1), seaweed extract (SWE) at rate of 100 g fed^-1 and filter mud (FM) at rate of 5 kgfed^-1). While the sub main plot using synthetic soil conditioners as zero addition, carboxymethyl cellulose (CMC) at rate 2% and polyvinyl alcohol (PVA) at rate 0.2 %. Results cleared that the interference usage of organic soil conditioners in combination with synthetic soil conditioners had positively affect hydro-physical properties of the soil, i.e., decreasing soil bulk density, increasing total porosity along with dry stable aggregate, as well as, the superior treatment is SWE + CMC. In general, there is no valuable difference between SWE and organic residues, whereas, YS and FM have the same trend over to control. In addition, organic matter (OM) and available macronutrients N, P and K content in soil were increased significantly with all treatments applied compared to control, the maximum increases were observed with SWE application mixed with CMC. An opposite trend was obtained with both pH and EC values which generally decreased at all applied treatments especially with (SWE+ CMC) Therefore, the application of seaweed as organic soil conditioner individually or mixed with CMC or PVA which increased significantly both wheat and peanut biological yields, straw grain and/or seed, along with total N, P and K content as compared to either control or other organic treatments application. Moreover, obtained results showed highly significant correlation ( p< 0.05) between grain and/or yield and soil EC, OM, P and N in spite of none significant correlation with pH and K. Finally, it can be concluded that organic soil conditioner especially seaweed and sugar cane byproduct was enhanced and became more effective when applied with polymers especially CMC.