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Sub: Alternate Wetting and Drying (AWD) Method

Presenter; Md. Nazim Uddin Mondal, M.Sc. UK. PGT. China and India,

WELCOME

How much water do people use ?

Liters of water

Daily drinking water 2-5 liters of water

Daily household use 20-500 liters of water

1 Kg of Rice 3000-5000 liters of water input to the field

Alternate Wetting and Drying (AWD) Method

Background

Boro rice in Bangladesh, whether HYV or traditional varieties covering more than 4.09 million ha, is entirely irrigated, mostly with underground water. Because of increasing cost of fuel, irrigation has become a very costly input in rice production. Farmers pay about 25-30% of the rice outlet for irrigation. For producing 1 kg of paddy, it is estimated that a farmer has to use 3,000-5,000 liters of water for keeping ponded water during the growing stage of plants. Therefore, farmers irrigate quite frequently and keep the field flooded all the times.

Hydrological cycle of water in rice field

.Transplanted rice in the wet land culture field

mm/day Season (100day)mm

Land preparation 175-750

Evapotranaspiration-wet season-Dry season

4-56-7

30% E, 70% T400-500 600-700

Seepage & Percolation-Heavy clays -Loam/sandy soils

1-5 25-30

100-500 2500-3000

Total season Typical- 1500mm

675-4450mm

Water requirement in lowland rice

Background (cont)

International Rice Research Institute conducted research on reducing frequency of irrigation. Recent research at IRRI demonstrated that ponded water all the time in rice field is not necessary. A simple device has been designed to observe water level in the ground to decide on the time of irrigation. It involves installation of a perforated water tube in the field to allow observation of water table. Irrigation is provided when the water table reaches 15 cm below the surface. With the use of this device, irrigation frequency can be brought down by 30-50% of traditional irrigation practice without affecting yield

AWD pipe perforated 15 cm and un perforated 5cm

AWD pipe in rice field

.

Tensiometer

Background (cont) Bangladesh Agricultural Development Corporation

has also tested this technology during 2006 boro season in Madhupur farm successfully. Only 4 irrigations were needed as against 8 irrigations. During 2007 boro season, 5 irrigations were needed following the new practice as compared to 9 irrigations as per conventional practice. Bangladesh Rice Research Institute and Rural Development Academy, Bogra are conducting research on this technique, with technical assistance from IRRI, for validation and scaling up.

Background (cont)

The technology has far reaching implication apart from direct cost-savings for the farmers. It will save burning of imported diesel fuel, which in turn will save money for the nation. It will also greatly reduce over-pumping of ground water and, therefore, reduce ground water depletion. All these benefits will have positive impact on the environment and natural resources conservation

Monitoring water level in the rice field

Method

Boro rice in Bangladesh is fully irrigated and the aman rice is partly irrigated. An estimated 3,000 to 5,000 litres of water is required to produce one kilogram of rice. Recent research at IRRI has proven that using Alternate Wetting and Drying (AWD), about 15-30%, if not more, could be saved without reduction in yield. Starting from about 15 days after transplanting, irrigate until the water table goes 15 cm below the ground level.

Water is there in root zone

Keep 5cm flooded water at flowering

Method (Cont)

A PVC pipe with 7-10cm diameter and 25 cm long with 15 cm perforation (picture below) is used. Plastic water bottle, bamboo or earthen pipe can be used to manufacture a AWD pipe. Dig a 15 cm deep hole in the rice field and install a perforated plastic pipe to monitor the level of the water table after each irrigation. The instillation can be done by pressing the PVC pipe down to the soil if the soil is soft enough. In this case the soil inside the pipe should be thrown away.

Installation of AWD Pipe in Rice field

Method(Continued)

In one bigha of land one pipe is enough placing the pipe in a easy going level area of the plot. To monitor we have to observe the water level goes down to the bottom of the pipe. When the water is at the bottom of the pipe we have to apply irrigation for 5-7 cm standing water. Continue the practice until flowering starts. Keep 2-4 cm standing water from flowering to dough stage.

Method(Continued

. This is now being valided in Bangladesh by BRRI, BADC, BMDA and other partners. The savings of irrigation water will have impact on environment because of reduced withdrawal of ground water, reduction in burning diesel. This may also reduce arsenic contamination in rice grain and straw.

Main idea to convey:

• • Water is there even when you can’t see it• Create confidence by farmers• Farmers then to experiment with threshold value• No recipe for soil type, hydrology, variety.

Final Remarks:

• AWD already existed for long time• The water tube: pivotal role in dissemination• In BD: 10% reduction in water means reducing 40 L of gasoline/ha. If only half of boro rice area apply AWD, we can save 80 ML of gasoline• AWD also reduces Arsenic in the soil and plant