This study was performed to select the optimum combinations of a cropping system by using kenaf and four forage crops on the reclaimed land, Saemangum, in Korea. First, kenaf was cultivated for 168 days from May to mid October, and then, four forage crops, such as barley, Italian ryegrass (IRG), rye, and triticale, were cultivated from late October to May next year. The agronomic performances and physiochemical analyses of kenaf and four forage crops were investigated. The kenaf yield on the reclaimed land was 2.4 t/10a compared to the upland field’s yield of 3.25 t/10a. The germination percentage of IRG was the highest in the solution of 0.3% NaCl in comparison with the other forage crops. The agronomic performances of forage crops were estimated twice during the vegetative period. A significant difference in dry weight was observed in barley at 30 days of sowing. On second investigation at 160 days of sowing, the highest plant height was found in rye and the dry weight of IRG was the lowest. At harvest time, rye showed a significant difference in the plant height of 159.8 cm and fresh weight was the highest in IRG. At this time, there was a big difference in the dry weight of rye and IRG compared to barley and triticale. With respect to the K+/Na+ ratio, rye showed the highest increase in the K+/Na+ ratio over the other crops when cultivated on the reclaimed land. With respect to the effect of the kenaf extract on the four winter crops, the extract from kenaf reduced the germination of IRG by 81.7%. With respect to the silage quality estimation, there was no increase in barley in terms of total digestible nutrient (TDN). Taken together, IRG would be useful for the silage and rye would be useful for green manure on the reclaimed land after cultivating kenaf.