Choosing the proper size of rice combine harvesters and soil moisture content are crucial factors in maintaining the soil from over-compacting and avoiding harmful effects on its physical properties and vital activities. This study aims to assess the effect of using four types of rice combine harvesters (4-rows with cereal collecting tank 4-HRC, 4-rows with cereal discharge tank 4-HRD, 5-rows with cereal discharge tank 5-HRD, and 6-rows with cereal discharge tank 6-HRD) on the soil's physical properties (bulk density, pore volume, penetration resistance, crawler print sinkage at the soil surface), soil micro-organism activities (total microbial count and dehydrogenase enzyme activity), and the next crop growth properties (plants /m2 and forage yield), under three different soil moisture contents (30-35%, 35-40%, and 40-45%). The results revealed that the 6-HRD harvester induced the highest soil bulk density, penetration resistance, and crawler print sinkage compared with the other harvesters. However, the minimum values were associated with the 4-HRC harvester. The soil moisture content of 30-35% showed low values of bulk density, crawler print sinkage, and penetration resistance compared to the soil moisture content of 35-40% and 40-45%. The soil microbial count and soil dehydrogenase enzyme activity are inversely proportional to the soil compaction level at all combine harvesters and soil moisture contents. The values of the total count of fungi, actinomycetes and bacteria, and dehydrogenase activity were found to be decreased as the combine size (width) increased.