Water Requirements for Non-tilled Paddy Fields in Hachiro-gata

Polder during Second and Third Year Non-tilled Farming

Abstract

Water requirements for non-tilled and tilled paddy fields with marshy heavy clay soil in Hachiro-gata polder were examined during second and third year non-tilled farming.
The following results were obtained:
1) To facilitate the transplantation of what; the soil surface of non-tilled paddy field should be covered initially with water and softened. The daily consumption following its introduction into non-tilled paddy fields was found to be as much as 30 mm, though 20 mm on the average. Based on the relation of daily water consumption to ponding depth and soil hardness, a method for water management to keep the soil of non-tilled paddy fields sufficiently soft was established.
2) Water requirement for non-tilled paddy fields was 15.8 mm/d in the second year and 12.6 mmjd in the third year during irrigation. Water requirement thus does not appear to increase yearly since the soil texture is marshy heavy clay called muddy sediment and the groundwater level for such fields is high. Horizontal percolation in non-tilled paddy fields was 10 mm/d in the second year and 8 mm/d in the third year. In non-tilled paddy fields, this parameter was greater than for tilled paddy fields.