Water is life. Humans, animals and plants need it to survive. Rice is a semi-aquatic plant. It needs soil nutrients, sunlight and water to grow. According to the Arkansas Rice Production Handbook, “proper management of irrigation is critical for management of disease (such as rice blast), nutrient management (such as nitrogen and phosphorus), weed management and insect management and overall profitability,”
Farmers use many different methods to flood rice fields: cascading water from the top of the field through each rice paddy, multiple inlet irrigation using poly tubing, furrow-irrigation using surface water and well water.
To sustainably grow rice, farmers practice different methods of water conservation to reduce how much water they use from wells. Before tapping into the limited supply of ground water, farmers use surface water and innovative methods to catch surface water.
Surface water is the water in rivers, streams, creeks, lakes, bayous and reservoirs. It is found on the surface of the earth. “The ability to capture, store and reuse irrigation water on farm offers many advantages including greater control and flexibility of water supply for irrigation, reduced groundwater dependence and energy costs from pumping [water] and reduced off-farm impacts on water quality by capturing sediment and nutrient losses in runoff.”
So how do farmers access valuable surface water while conserving ground water?
They use irrigation reservoirs, tailwater recovery ditches, conveyance ditches or underground pipeline, pumping stations and irrigation risers, and some farmers use a combination of these water management techniques to make a unique setup for each farm.
Some farmers pump surface water from reservoirs across the farm, using underground pipeline or a series of ditches, to fields with less access to water sources. This helps farmers to not tap into the ground water sources from wells until it becomes necessary.
Flow meters are installed on pumps to measure water flow rate and the total volume of water applied. They allow farmers to know how much water a pump can push out onto a field and the rate the water flows.
In the photos of the propeller pump above, the water flows through the pipe, and a propeller spins. The speed the water moves through the pipe is used to calculate flow rate. Farmers want to use less water and less time pumping it to conserve as much water and energy as possible.
Multiple inlet irrigation is a system which distributes water evenly over the entire field at one time. A pump is located at the highest elevation of the field. The poly tubing attaches to the pump, and it is rolled out along the side of the rice field, and sometimes through the rice field.
The farmer will activate the pump, and water will begin to flow through the poly tubing. The farmer will strategically punch holes into the poly tubing to flood each rice paddy, as well as poke air holes so any pressure built up can escape without bursting the entire tube.
Multiple inlet irrigation helps farmers establish an even flood environment quicker, reduces the amount of water used, reduces water pumping time and cost and reduces water runoff from fields.
Tailwater recovery ditches catch any water run off or overflow at the bottom of the field, as well as any overflow from on-farm reservoirs. Farmer recycle the captured water and use it to maintain the flood, or they pump it back into the main reservoir to use at a later time.
Check back every Wednesday to learn more about other irrigation systems used on the farm, the science of rice after the flood is established and much more in the From Riceland Farms series.