Agricultural water management there is most uncontrollable element in farming is weather. Subsurface water management gives producers an opportunity to regain some control from unpredictable weather. An effective water management system is essential for crops to attain their full potential and maximum yield it allows for proper soil composition and optimal root development maximizing plant strength and nutrient uptake.
The key visible features of a water management system include the outlet, a ditch or stream to carry excess water away, and a buffer strip to shield the stream from overland soil erosion. As rain enters the system, it is what happens below ground that makes a water management system so valuable.
The large diameter pipe is called a main. The job of the main is to take excess water from the field and direct it out of the system. The smaller pipes are called laterals and form a pattern or grid across the field collecting excess moisture and carrying that water to the main. Laterals are usually spaced 30 to 75 [feet] apart and are buried two and a half to four feet deep depending on soil type.
The main is always deeper than the laterals as water moves through the system using gravity. Water flows to lowest point which is always the outlet. Water enters laterals through small perforations or slits in the pipe. The perforations are designed to allow water in and to keep soil out. From a side we see the main note the water table is just below the main.
Water Management System:
A properly designed water management system does not take all the water out of the soil, it manages the water table to keep it at a constant depth which is usually three to five feet below the soil surface. By managing the water table the optimal soil profile for plant growth is achieved. The soil profile is the area from the soil surface to two and a half to four feet below. This area is where nutrients are taken up by [the] plant roots.
Ideal soil properties in the profile are 50% minerals and organic matter, 25% air, and 25% water. A cross-section of the main reveals the laterals entering allowing the water to flow downhill into the main. As rain begins above ground the soil profile is able to accept water from the surface as it filters down. Once the water reaches the perforated laterals excess water enters a system and begins flowing to the main Compare that with the same field without a water management system.
The water table is higher with less area available to absorb water. When the soil reaches full saturation and rain continues excess water cannot soak into the ground. The only place for excess water to go is to flow [overland] to the lowest point carrying with it valuable soil and nutrients. This will cause erosion of surface soil dumping sediment and nutrients into the ditch or stream. A water management system allows more water to be filtered [through] the soil and less risk of soil erosion.
As a soil profile reaches full saturation the rain ends excess water filters down to the laterals into the main and out of the system through the outlet. This reduces [the] amount of water in the soil profile. It is important to recall for optimal plant health [25%] of the soil profile should be air if not plant roots will be deprived and necessary oxygen and cause plant death. As excess water leaves the main into the ditch or stream the soil profile continues to take in needed [oxygen]. A water control structure features adjustable stop logs that can be added or removed depending on the time of year and weather conditions.
When an extended dry period Is anticipated the stop logs are placed in the structure at a level that will temporarily raise the water table. As water enters the system it is held in the pipes by leaving additional moisture in the soil profile for thirsty plants. When the system is saturated and the pipes are full, excess water flows over the stop logs and through the outlet. Stop logs can be adjusted to hold water in the system particularly after planting in the spring and prior to extended dry periods throughout the growing season.
UV Radiation Systems:
When water touches the fruits and vegetables that we eat, we need to make sure that irrigation water is clean so that we reduce the risk of someone getting sick. When our water does not meet the agricultural water standards in the Produce Safety Rule, we can treat it using various methods. Filter the water to reduce turbidity before it enters any treatment system. Water hardness, salinity, and other aspects can impact your pH and chlorine levels.
UV radiation systems have been approved by scientists and are safe to use. UV light kills pathogens and other organisms like E. coli by exposing pathogens to radiation in a UV disinfection system. Tablet chlorinator and chemical injector systems use chemicals to sanitize water. As a producer, you have the power to monitor your systems and ensure that irrigation water is of good sanitary quality. Finding the right system that meets your needs requires some planning. In addition to the system being validated for treating agricultural water, there are pros and cons based on cost and maintenance, your water source, water quality, and soil type.
If you’re having trouble selecting the right system, discuss options with your Extension agent or food safety specialist. Scientists validate treatment systems by doing experiments to understand what works to kill pathogens and indicator organisms like E. coli, and what conditions are important to control during treatment. When you select a validated method like chemical injection, tablet chlorination, or UV light, this work has been done for you, and you just need to validate that the system is installed and operated the same way on your farm.
Monitoring. Make sure to have a set of standard operating procedures for your equipment, and make sure all employees are trained in these procedures. Monitor systems to make sure the equipment is working properly, and test the water to make sure the system is effective.Verification. Whichever system you pick, you will write standard operating procedures, which are a set of instructions to make sure the system is used correctly. You verify that your employees are always using the system the way you specified. Follow the instructions, and use the system properly.