Four field trials were conducted, through the period from 1997 to 2000. to evaluate the beneficial effect of using Agar Agar (Agar) as a new soil conditioner under field conditions. Two wheat field trials were conducted at two sites, Sakha Experimental Station (clay soil) in 1997/ 1998 and Ismaielia Experimental Satiation (sandy soil) in 1998/1999. The two sites were cultivated with the two wheat varieties Sakha 61 and Sakha 69, respectively. Mother two peanut (cv. Giza 5) field trials were conducted in 1997 and 2000 in sandy soil at Ismalelia Experimental Sta-tion. Agar solutions at very low rates, alone or In combination with a bal‌anced compound fertilizer were applied by using two easy techniques, of either soaking seeds pre-sowing or spraying soil under the growing plants. The obtained results emphasized that: 1- Applying Agar by soaking wheat seeds in Agar solution of 0.1% for four hours pro planting had an adverse effect on grain and straw yield in the clay soil at Sakha. Conversely, spraying the sandy soil (after one month from planting) at Ismalelia under the growing plants of wheat with Agar solution of 0.1% containing the compound fertilizer named Foliar-X at the rate of 0.25% significantly increased the yields of both grain and straw over those of control treatments by 37.0% and 58.9 % respectively. 2- Soaking peanut seeds in Agar solution for one hour pre plant‌ing significantly increased the yield. The lowest concentration of 0.01% was the most effective one wherein the seed yield increased by 101.5% then declined to 69.3% with 0.2%; while increasing such concentration to 0.4% in the second season increased it by only 40.4% over seed yield of control treatment. Also, spraying sandy soil with Agar solution of 0.1% under grow‌ing peanut plants significantly Increased the pod and seed yields over those sprayed with water in the second season. However the best seed yield was obtained when Agar solution, used for soaking seeds or spray‌ing soil under plants after one month from planting, was combined with the balanced fertilizer Novatrin; wherein an increase of 49.7% and 48.2% over those treated with water was achieved, respectively. The N, P and K content as Kg/leddan in seeds exhibited the same pattern exist‌ed with the seed yield.