The following practices greatly reduce the amount of water required for irrigation and the frequency of irrigation needed to produce healthy and productive plants within a thriving ecosystem.
Compost has a high water retention capacity. It thus allows for less irrigation in terms of quantity of water and frequency of irrigation.
Mulch reduced evaporation of water from the soil by shielding it from direct sunlight and absorbing the heat and high energy in itself. Straw mulch is a good option.
Irrigating at night reduces evaporation considerably by allowing the water to seep through the soil overnight while the plant roots get an ample chance to take the dissolved nutrients in it. This reduces evaporation considerably compared to irrigating in the morning when the heat and wind could evaporate a large percentage of the water from the surface of the soil and through heavy plant transpiration.
Disturbing the soil by digging exposes beneficial microorganisms living inside the soil to increased amounts of oxygen that kills a great number of them. Disturbing the soil by digging it also destroys the very fabric of the soil destroying its ability to retain water for long periods of time. As a result, plant roots are adversely affected by digging and disturbing the soil. More water and more frequent irrigation is required in case of disturbing the topsoil to compensate for the damage caused to the soil internal fabric and the otherwise thriving microorganisms living inside it.
It is thus wise to leave the soil alone without digging, particularly after planting a plant in it, in order to have good healthy plants and to required way less amounts of water for irrigation and less irrigation frequency.
Plants that are trained to use less water by irrigating using smaller amounts of water and, more importantly, along extended periods of time tend to become more drought tolerant. The plants get used to consuming less water and surviving for longer periods without frequent irrigation. Training plants gradually to consume less water triggers a number of adaptation mechanisms in plants to require less irrigation.
One such adaptation technique used by plants to adapt to infrequent irrigation situations is to develop deeper roots that search deep in the soil for water. Such deep roots enable the plant to require irrigation much less often as they fetch the water from deeper soil layers which have a capacity for retaining water much more than the upper layers of the soil. On the other hand, if the plant was used to frequent irrigation, it will not do any effort to extend its roots downwards deeply and thus will require much more frequent irrigation and will suffer greatly if it suddenly lost its high dose of near-reach irrigation water.
Growing a diverse set of companion plants together in close proximity can help them benefit from one another forming a sort of collaborative community one of the benefits of which are conserving water. For water to be conserved, some of the plants should be tall and sun-loving with the ability to shade the other plants. The shading of sun-loving taller plants (such as trees) will reduce evaporation of water considerably by reducing the transpiration from the shaded plants as well as making the surface of the soil cooler.
Instead of flooding the soil with huge amounts of water and giving it a strong shock, it is better to first irrigate the soil lightly, wait for a few minutes then go ahead and continue the irrigation. The initial light irrigation allows the soil the absorb the water on its own pace and changes the physical properties of the soil enabling it to retain much more water when it is irrigated again after a few minutes.