AWD System – Alternate Wetting and Drying
In the future it is thought that many rice farms may suffer from scarce water supplies which can have a big impact on rice farmers and their crops. However there are areas right now that will be suffering from low water supplies damaging their crop output. One method that has been introduced to help reduce up to an estimated 25% of water consumption is AWD. It is important to note that rice plants do not need to have standing water in the fields to produce the growth of rice plants. AWD takes this into play by minimizing the water usage but continuing to produce the same quality of crop output.
This method is very simple to implement in any rice paddy field, the only real piece of equipment you need is a water tube that is utilized as a water measure. They are not hard to manufacture and are very useful for observing water depth below the ground. The minimal size of the water tube should be around 40cm in height which has a 15cm diameter. Puncture holes should also be created around 1 cm in length for water flow to enter the water tube.
The following steps are used as a guide that has been proven to work using the AWD method:
Step 1 – Implementing the Water Tube
Once you have obtained a water tube you are going to want to place it into the ground, specifically near the edge of the rice paddy field but at least a meter inwards of the field to get an accurate reading. Placing the tube to close to the edge is not ideal as it may be more unlevelled and allows better access to debris and pests. Ideally you want to place most of the tube into the ground roughly at least 15-20cm in depth but leaving enough room at the top so the tube won’t get submerged by the standing water in the field. Lastly clear out any mud or debris that has gotten into the tube. If the field has already been filled with water it’s good to check the level of water in the tub making sure it is level with the surrounding water, if not water levels won’t be measured accurately.
Step 2 – Adding water
Before implementing the AWD method you want to ensure the rice plants have already grown to around 10cm from ground level after direct seeding has taken place, or a few days after transplanting has occurred. After this time you can begin to add water. When adding water to the field you want to raise the water levels to around 5cm off the ground, this will give sufficient water on the surface.
Step 3 – Minimal Water Levels
When water is lost through the associated processes it will continue to drop or increase if much rainfall is produced. It is important to watch the water levels on the tube so that levels do not drop too far and stop water access from the rice plants roots. If you have not implemented the AWD water management method then it is ideal to go with the measurements of 15cm. When water levels drop to 15cm underground it is time to supply more water to the field. Water should be topped up to at least 5cm over ground.
These measurements are proven to work however it is good to experiment with the levels of water. You may want to wait until water levels decrease to 20 or 25 cm underground before topping up more water. Just try to ensure that the roots of the rice plant continue to access the water underground. As long as the roots have enough access to water then the crop output should still produce the best results from water gain. Do not worry if you see cracks in the ground appear from drying, all that matters is the access to water from the roots.
Step 4 – Repeating Steps
Continue to repeat these steps. Keep in mind that around a week before flowering is to take place the water levels should NOT drop below 5cm until a week after flowering has completed. If you do not keep a constant water level during this time then you may see some crop detrimental effects. Also do not start implementing the AWD method before the rice plants are at least 10cm from ground level after direct seeding or at least a few days after transplanting has taken place.
Benefits of AWD
The main benefits from implementing the use of AWD are the decrease in water consumption and increase of soil aeration. Water is a vital source for all rice farmers which affects their whole crop output, however some areas may be limited to water supplies which furthers the necessity of reserving water. Not only does AWD take into account water consumption but also soil aeration which is important to the plants for the intake of gasses. Gasses such as nitrogen and carbon dioxide help in the plants efficiency in getting nutrients and water from the ground as well as making plants more resistant and capable of growing in stressful situations. Therefore getting aeration into the soil is helpful to the yield.
Disadvantages of AWD
Many methods to a solution have downfalls of some sort or another, and where AWD is concerned although it does help in the decrease of water consumption it has a slight disadvantage. Extra care in observing water levels is required due to AWD trying to push water levels to low measurements. By doing this the leeway of water levels decrease so there is not much room for error in recording accurate water levels.
Ensuring the field water tube is accurate and maintained well will really disregard this disadvantage, however for any reason recordings are not accurate it may have an impact on yield outputs. More significantly the further the leeway of water levels are decreased, the chance of rice plants getting access to water is also decreased.
