Puddling is the most common method of land preparation for wetland rice (Ory.:a sativa L.) in south and southeast Asia. While this method has certain advantages, it is time-, energy-, and capitalintensive. The objective of this study was to identify time-, energy-, and capital-efficient tillage techniques for sustained productivity of wetland rice soils. The effects of different land preparation techniques on soil physical properties, root growth, and grain yield of wetland rice (cv. IR36) on two Philippine (IRRI) soils are reported. Bulk density, penetration resistance, and temperature of surface soil layers decreased with tillage intensity. In clay ~oil (Andaqueptic Haplaquoll with a water table of 0.30 m), the average daily water use (percolation + seepage + evapotranspiration) during a 90-d irrigation period for zero tillage (dry-seeded rice) was 37 mm d-1 ; zero tillage (transplanted rice), 35 mm d--1 ; minimum tillage, 34 mm d-1 ; and puddling, 30 mm d-1 • The corresponding values for the clay loam (Typic Argiudoll with a water table > 1.2 m) were 393, 501, 263, and 164 mm d-1 , respectively. Root-length density (RLD) at the 0-to 0.10-m depth at harvest was negatively correlated with soil bulk density at transplanting. On the other hand, grain yield was positively correlated with RLD, but negatively correlated with bulk density and soil penetration resistance and was less on zero-tilled than on tilled plots. For the clay soil, grain yield (two-season average) with minimum tillage was 26% higher than with zero tillage. For shallow puddling (one-season data) and puddling, the figures were 33 and 28% higher. The corresponding values in clay loam soil were 36, 66, and 56%, respectively. Zero and minimum tillage plots dried faster than puddled plots after they were drained at harvest; surface cracking was higher in puddled plots. In the clay soil and in both seasons, minimum tillage produced the same grain yield as puddling, and in such soil, minimum tillage may be an alternative to puddling, provided weeds are controlled.------------------.A.dditiolllll index words: Bulk density, Soil penetration resistance, Soil temperature, Total water use, Root-length density, Root-mass density, Ory<;a sativa L.-----------------T HE MOST common method of land preparation for wetland rice in south and southeast Asia is puddling. This method has certain advantages: weed control, ease of transplanting, and reduction in percolation of water and leaching of plant nutrients. Nonetheless, it is time-, energy-, and capital-intensive. In addition, it creates soil physical conditions that are not suitable for crops following wetland rice and, hence,
