Levees are created to produce a controlled flood environment in rice fields. If water was allowed to flow freely across a field without levees, parts of the field would receive no water while other parts would receive too much water. The optimal flood level of water across a field during the growing season is about four inches deep.
While the lines in the field may look haphazard, science and technology are used to survey rice fields. The shape of the levees is determined by the elevation of the land. There are two ways farmers can survey fields: base station and laser technology and GPS technology. The base station and laser technology uses two pieces of equipment to survey levees. A base station is placed in a field. It emits a laser beam to the rover mounted outside of the tractor.
The tractor's onboard rover receiver reads data from the base station.
As the farmer moves across the field, he watches the indicator lights. When the elevation of the field changes, the arrows above or below the indictator lights will turn red. The farmer will then turn left or right to maintain the proper elevation across the field. A farmer using the laser and base station method for surveying fields will survey the fields each year.
A digger is attached behind the tractor to dig the surveyed lines, which mark the levees.
The other way to survey levees is using GPS technology. It uses Real-Time Kinematic capabilities to survey the land, where the data is saved so farmers can reuse it. For more information on GSP technology and surveying rice fields, stay tuned for next week's From Riceland Farms post, which details the process.
Levees are now ready to be created. The farmer will use a levee plow to till the soil and pull it inward to create a seamless line of pyramid-shaped soil that follows the surveyed lines across the field.
After a levee is pulled, the farmer will make a second pass to plant rice seeds and squeeze the levees to ensure more seed to soil contact when making a seed bed. This provides the optimal environment for the rice seed to grow.