What are the factors affecting drip uniformity in drip irrigation system?

For high yield and high quality crops, irrigation uniformity is very important. It is possible to fertilize evenly during drip irrigation if the water is evenly irrigated. The factors that affect the dripping uniformity of the system are:

1. Factors in the manufacture of drip tape irrigation system drippers

To make the drip tape irrigation system evenly irrigated, first of all, the water from the single dripper should be uniform. The parameter that reflects whether the single dripper emits water uniformly is the manufacturing deviation, which is expressed by Cv. The size of the manufacturing deviation reflects the manufacturing precision of the manufacturer. The smaller the manufacturing deviation, the better the uniformity of the single dripper.

2. Sensitivity of drip tape irrigation system dripper flow to pressure changes: flow index

Usually on flat ground, the pressure at the head of the capillary is high and lowers further back. If the sensitivity is high, the further back, the lower the water output, which affects the yield and quality. The relationship between the dripper flow and the working pressure is expressed by:

where:

q—Dripper flow (liters/hour);

h—working pressure (m);

k—flow parameter;

x—fluidity index.

The flow index x reflects the sensitivity of the flow rate of the dripper to pressure changes:

– When the water flow in the dripper is full laminar flow, the flow state index x is equal to 1, that is, the flow rate is proportional to the working water head;

– When the water flow in the dripper is fully turbulent, the flow index x is equal to 0.5;

– When the flow state index x is equal to 0, that is, the effluent flow is not affected by pressure changes, this state is called the full pressure compensation state.

The flow index of other various forms of drip tape irrigation system emitters varies between 0 and 1.0.

3. Pressure compensation and non-compensation performance of drip tape irrigation system

Drippers can be divided into pressure-compensated and non-pressure-compensated drippers. The pressure compensated automatic dripper is equipped with a flow channel adjustment diaphragm. When the pressure is high, reduce the flow section to reduce the water output. When the pressure is high, the flow section is enlarged to increase the water output. Pressure-compensated dripper delivers even water. It can extend the laying length of drip irrigation pipes, improve the uniformity of drip trickle irrigation, and better meet the requirements of plants for water and fertilizer.

There is no diaphragm in the flow path of the non-pressure compensated dripper. The water output varies with the pressure at the dripper. Irrigation uniformity is low. If the capillary laying is short and the pressure of the dripper does not change much, the non-pressure compensation dripper can be considered to save investment. In mountainous areas, the pressure changes greatly, and it is best to use a pressure-compensated drip irrigation pipe.