One needs to know the power consumption of the pump

and the total time it is running

If the pumping scenario is constant pumping rate / consistent power consumption it is sufficient to totalize the time the pump runs.

Some irrigation systems use simple time-of-day timers

in which case programmed hours X pump kW = kWh

Some irrigation systems use various control strategies rather

than fixed interval timers. In that case you need to find a way

to totalize the run time...

A simple technique is to just run a simple analog (non-electronic) clock on the same power circuit as the pump. As the pump runs the clock will count up the time. Reset as required

If you can measure, then why calculate. Measurement will always be better. Digital meters are cheap and easy to install and the best option.

Shaikh Shamser Ali

Yes, your suggestion is indeed optimal - if circumstances and resources allow.

I restrained myself to the specified context.

I assume there may be a broader context and it would be beneficial for the entire scenario to be presented.

What is the purpose behind knowing the energy consumed ?

Is there an intention to optimize the irrigation system?

For example, the default approach to irrigation may be to use a pump to create active pressure in the distribution system piping which then supplies nozzles which spray water onto the crops - perhaps using a timer.

A refinement of that may be to use drip nozzles which reduce the evaporative losses and perhaps soil-humidity as a control parameter rather than timers...

A further refinement can be obtained with porous tubing buried in the soil along the plants which may required only static pressure from elevated tanks and require pumping only to maintain water level in those tanks.

This may be particularly applicable for specialty medicinal and aromatic plants - as opposed to conventional row cropping ...

While the narrow question of total energy consumption has some utility, I am quite sure that there are broader questions stimulating that question.

Install an Energy meter.

Irrigation pumps rarely operate steadily: the inlet filters block and the flowrate varies over the day. This makes prediction of energy usage very difficult. A kWh meter is fairly simple and accurate, but does not give good enough information on the efficiency of the pumps or the filter-blocking rate. The fluid flowrate and head difference as well as the kW usage are needed if a proper appreciation is required. A simple algorithm can then show pump efficiency and prevent power wastage and reduce failure-rates.

Jack Broughton

sounds like you are advocating for a fully instrumented autonomous PLC based control strategy - perhaps even with auto-backflush filter streams ?

With unrestrained budgets which one might enjoy in some priviledged regimes, one might also then look at optimizing the wet-end of the irrigation strategy as well...

Replace open-air sprinkler systems with drip / in-ground systems to reduce evaporative losses and reduce operating pressure requirements

so that with the addition of elevated tanks to provide static pressure thereby reducing dependency on maintaining (continuous) dynamic pressure

Very little is known about the overall scope and scale from the question.

Kurt Klingbell: we mainly work on systems for cane sugar factories. My notes are related to typical situations for these based on river water supply. The inlet filters are generally manually cleaned (but not often enough), also river levels vary widely over the year. A bigger problem is maintaining the instruments, but that is not a technical issue: we often have to use manual readings rather than central SCADA data.