Rice crop growth and yield as influenced by changes in ponding water depth, water regime and fertigation level

Irregularities in land leveling, such as low lying areas or reverse grades, can cause too little or too much ponding water depth resulting in a variation in the crop yield within a plot, especially if paddy field is a large sized one. Experiments were conducted in Wagner pots to evaluate the effect of different ponding depths (created by surface irrigation practice) on paddy rice growth and yield. Wide ranges of ponding water depths were created under continuous, intermittent and variable ponding water regimes and under no, low, medium and high fertigation conditions. Plant height and grain yield were measured under 0, 3, 6, 9, 12, 15 and 18 cm ponding depth treatments. Results indicated that an optimum ponding depth of 9 cm can improve paddy growth and production conditions compared to too shallow or too deep ponding water depths. High values of water productivity were found at 9 cm ponding water depth under different water regimes and fertigation levels. Less yield reduction occurred at shallower depths than that of deeper ponding depths. Hence, high leveling accuracy is needed in paddy fields to have maximum production.