Green thumb gardening
how to prevent
Clogging
of
Emitters in drip irrigation
by Guy Sela A micro-irrigation system should be properly planned and managed in order to fully
benefit from its many advantages. One of the main concerns is keeping drip emitters from clogging.
Fortunately, it’s a problem that is easy to solve.
Micro-irrigation systems come with many advantages over other
types of irrigation. When using such a system, delivery of water
and nutrients to the root zone is more uniform and runoff is prevented. In addition, weed population is better controlled and the
less humid environment helps better control pests and diseases.
Sub-surface irrigation presents some additional advantages.
Drip emitters are protected, and runoff and evaporation
are minimized, increasing irrigation efficiency even more.
Nevertheless, micro-irrigation systems should be properly
planned and managed in order to fully benefit from these
advantages. One of the main challenges is keeping drip emitters free from clogging, causes of which are categorized into
biological, physical and chemical types of debris. It is useful to
differentiate between surface water and ground water because
different water sources carry different plugging hazards.
Physical Causes of Emitter Clogging in Drip Irrigation
The most common physical causes of clogging of drip emitters are sand particles, which are usually found in surface
water. Other suspended solids might be too large to pass
through the emitter's opening and might clog it. Under
certain conditions, silt-sized particles can form larger aggregates that might cause clogging. Turbidity is often used as
an estimate of the suspended solids, but is not an accurate
indicator of the water’s clogging potential. An adequate filtration system, designed based on the quality of the water, can
prevent physical plugging of drip systems.
Biological Causes of Emitter Clogging in Drip Irrigation
Drip irrigation systems provide a favorable environment for
bacteria, fungi and algae that can cause slime accumulation.
Bacterial slime can be a direct cause for clogging of drippers,
but it can also induce mineral particles to stick together and
form aggregates large enough to clog the emitter openings.
142
Maximum Yield USA | February 2014
This phenomenon is significant when manganese, sulfide
and iron are present in the water.
Depending on the type of bacteria responsible for the slime,
its color might be reddish, yellowish or grayish. Clogging due
to micro-organisms is common when using water with high
biological activity, relatively high iron or manganese levels
and hydrogen sulfide compounds. Proper chlorination and
disinfection procedures are the key to controlling biological
clogging of drip irrigation systems.
Chemical Causes of Emitter Clogging in Drip Irrigation
The word chemical denotes mineral precipitation, which
might form when mineral solubility is low enough. Solubility
of a given mineral is dependent on the water temperature,
its pH, redox potential and the concentration of the mineral
elements present in the water. The common elements that
might clog drip emitters by precipitation and sedimentation
are calcium, magnesium, iron and manganese, with calcium
carbonate being the most common precipitate. Water that
contains high le