Sprinkler Controller: Open vs Closed Loop Systems

For some time there has been the capacity to provide the correct level of irrigation to plants using sprinkler controller in any area according to their needs. This is known as a closed loop system. At the same time we have many areas that are aware of the value of the closed loop system and yet insist upon using a timed delivery of irrigation regardless of plant needs. This is the open loop system.

The Closed Loop - Total Management

A closed loop system of irrigation monitors the environment to ensure that the water that is delivered is really necessary. Many different parameters are measured in commercial systems including soil moisture content and atmospheric humidity. Water that is delivered to an area that has just benefited from rainfall or some other irrigation action is wasted water. The plants can’t absorb it fast enough and the soil will probably get saturated and lose valuable ventilation.

A commercial farmer will often make calculations about the weather and decide how he should behave towards his plants based on many years of experience. This natural ability has now been adapted to machinery that can measure many of the effects that the farmer reacts instinctively to and use a complex set of guides to provide what the information suggests is needed.

Because this is a ‘set it and forget it’ exercise it seldom needs to be monitored. It will produce the best treatment for the plants and (often) livestock in a farm while making huge savings of scarce and valuable resources.

It is true to say that the system is not always so available to smaller agricultural concerns but many aspects of it are. It is very simple, for example, to have an irrigation system switch itself off if it detects that there is enough rain falling. It is also simple to have a system that will switch itself on if there is a crisis developing in the water content of the soil.
This level of economy and automation should be more wide spread.

The Open Loop

The open loop system is another automated system and it was once the very best available. Advances in technology have left the open loop system standing. Although it is still very common, especially among gardeners, the advances that can bring it up to date are not so widely publicized.

One aspect of the open loop is that no adjustment is made even for obvious situations like rain storms. If the irrigation is to be turned on and there is a torrential storm, nothing changes. The storm is augmented by the irrigation system. They are seldom even turned off manually in such circumstances.

There is no doubt that the closed loop system is far superior. There is also little justification for not adapting some of the technology to the open loop and cutting out some of the waste. Initial expenditure for simple measuring devices will soon be recovered in the form of savings in natural resources and cuts in utilities costs.