Soil Improvement (Ubon series) for Upland Rice   Seri Chaturangkakul Somnuk Sritongchim Yuwadee Buttrama Tongoon Naraekul Virat Talpibal and Arthit Sukhasem   ABSTRACT         Soil improvement (Ubon series) for upland rice was conducted at Roi - Et Land Development Station in 1992 - 1994. The experiment design in RCB replicated 3 times while treatments used in the study were ; T1 = Control T2 = Applied Stable manure 500 kg/rai with chemical fertilizer 20 kg/rai in the first year only T3 = As same as T2 but applied in every other year T4 = As same as T2 but applied in every year T5 = Applied Stable manure 1,000 kg/rai with chemical fertilizer 20 kg/rai in the first year only T6 = As same as T5 but applied in every other year T7 = As same as T5 but applied in every year T8 = Applied Stable manure 1,500 kg/rai with chemical fertilizer ( 16-16-8) 20 kg/rai in the first year only T9 = As same as T8 but applied in every other year T10 = As same as T8 but applied in every year The objective of this study were : to find out the best rate and residue effected of stable manure. The resulted showed that yield of upland rice was evidently increased while rates of stable manure were increased. Therefore, when upland rice applied with the rates of 500, 1,000, and 1,500 kg/rai the average yield were 126, 145 and 163 kg/rai respectively (16-16-8) 20 kg/rai alone the yield was 183 kg/rai only. Otherwise, rice yield applied with stable manure at the rates of 1,000 and 1,500 kg/rai can maintain its yield up to 2 years. In case of soil analysis showed that there is no different between before and after study as far as fertility was concerned.         Keyword: Ubon series, Upland Rice