Water management in paddy crop

Dr Laishram Kanta Singh, Dr Arati Ningombam, N Peetambari Devi and Dr S Roma Devi
Crop water requirement is the amount of water required by plants for survival, growth, and development, as well as the production of economic parts.  This demand is met either naturally through precipitation or artificially through irrigation. The daily consumption of rice ranges from 6-10 mm, and total water consumption ranges from 1100 to 1250 mm, depending on the agro-climatic environment, duration of variety, and soil characteristics.
Stage-wise water requirement for paddy
Stages of growth Water requirement (mm) Percentage of total water requirement---
Nursery Preparation 40 3.22
Paddy field preparation 200 16.12
Transplanting to panicle initial stage 458 37.00
Panicle initial stage to flowering stage 417 33.66
Flowering stage to maturity stage 125 10.00
Scheduling of irrigation for paddy
Short duration variety Medium duration variety Long duration variety Days No. of irrigationWater level (cm) Days No. of irrigation Water level(cm)DaysNo. of irrigation Water level (cm)1-255-72-31-305-72-31-356-82-325-Thin film of water30-Thin film of water 35-Thin film of water28-Life irrigation33-Life irrigation 38-Life irrigation 29-5062-534-656-82-539-90 or 9512-152-551-705-62-566-958-102-596- 1257- 92-571-1055-62-596-1256-82-5126-1505-62-5
Critical Stages of Irrigation
The critical stage of water need is the point at which water stress produces substantial yield decrease. It is often referred to as the moisture sensitive phase. Active tillering, Panicle initiation, Booting, Heading, and Flowering are critical stages of water requirement in rice. During these stages, the irrigation interval should not be extended beyond the time limit so that moisture is depleted below the saturation level. Continuous land submergence for rice is commonly used due to the accompanying primary benefits of increased nutrient availability and fewer weed management issues. Throughout the crop time, shallow submergence of water up to 5 cm depth is ideal for optimal production. Standing water in lowland rice reduces irrigation requirements, resulting in high water use efficiency as compared to continuous flowing irrigation water from crop to field.
Rice Field Water Losses
Water losses from lowland rice fields can be divided into two categories: vapour losses and liquid losses. Evapotranspiration refers to the loss of vapour through transpiration from the leaf surface and evaporation at the water surface. Deep percolation plus seepage and runoff of excess water over field levees are the two types of liquid losses. (To be contd)