Skeletal Soil Improvement by Mulching and Subirrigation with Earthen Cylinder for Sweet Tamarind Production   Seri Chaturongkakul and Somnuk Sritongchim   ABSTRACT         Skeletal soil improvement by mulching and subirrigation with porous earth cylinder for sweet tamarind production was conducted in Phuphan study center in 1986 - 1992 in Phon Pisai series follow by 6 treatments. T1 = watering conventionally and mulching with rice straw (15 litters for every 3 days) T2 = watering and mulching with rice hush (15 litters for every 3 days) T3 = used 2 earthen cylinders and mulching with rice straw T4 = used 2 earthen cylinders and mulching with rice husk T5 = used 3 earthen cylinders and mulching with rice straw T6 = used 3 earthen cylinders and mulching with rice husk *using porous earth cylinder contain 5 litters of water The result showed that during 1 - 4 years using 2 earthen cylinders was enough for growth of plant. But after 4 years earthen cylinder should be increased to 3 cylinder and mulching with rice straw or rice husk so that sweet tamarind could yielded 9.60 and 9.76 kg/plant respectively while plant treated with conventional watering mulching with rice straw and rice husk yielded only 5.43 and 6.56 kg/plant respectively.         Keywords : Mulching, Earthen Cylinder, Tomato