Irrigation efficiency in the face of drought: Why a well-nourished plant gets the most out of every drop.

04/06/2026 – Disclosure

Irrigation technology has advanced enormously, but the final word on how much water a crop actually uses is left to the plant itself: its roots, its nutrition and the soil life that supports it.

Agriculture is by far the world’s largest consumer of freshwater: it accounts for nearly 70% of global withdrawals, according to the FAO. In a scenario of more frequent and intense droughts, every drop of irrigation becomes a strategic resource.

The most visible response has been technological. Localized drip irrigation achieves efficiencies of 85-90%, far above sprinkler or gravity systems. This is an extraordinary advance. But irrigation efficiency does not end at the pipe: once the water reaches the root zone, it is the crop itself that decides how much it uses and how much it loses.

Efficiency does not end at the pipeline

Agronomists talk about water use efficiency (WUE): kilograms of crop per liter of water transpired. It’s a different concept than irrigation system efficiency. We can deliver water to the root with almost surgical precision and still have the crop waste it if it is not able to manage it well.

This management depends on three agronomic factors: how the root explores the soil, how the plant regulates its water losses through the leaf, and how alive the soil surrounding the root system is.

It all starts at the root

A well-nourished and stimulated plant develops a deeper and more ramified root system, capable of exploring more soil volume and accessing water that a weak root cannot reach. A microscopic ally is added to this exploration: arbuscular mycorrhizal fungi (AMF), which establish symbiosis with about 80% of terrestrial plants. Their hyphae extend as an extension of the root, improve soil-root hydraulic conductivity and reinforce the stability of soil aggregates and their water retention capacity (reviews in Journal of Experimental Botany, 2023; Frontiers in Plant Science, 2022). Under moderate water deficit conditions, inoculation with mycorrhizae can double biomass in crops such as maize.

Potassium: The “Tap” that regulates every leaf

If the root is the water inlet, the leaves are the outlet. And there, one nutrient makes the difference: potassium. It regulates the opening and closing of the stomata, the pores through which the plant loses water through transpiration. A crop well supplied with potassium maintains greater cell turgor, better relative water content and a significantly higher WUE. Deficiency, on the other hand, throws transpiration out of control and aggravates the effects of drought (reviews in Agronomy, MDPI; Plant Physiology and Biochemistry).

Osmotic adjustment: Keep water in.

Under stress, plants accumulate osmolytes such as proline or glycine betaine that reduce the osmotic potential and allow them to retain water even when the soil begins to dry out. This is known as osmotic adjustment. Certain biostimulants favor this mechanism, reinforce antioxidant systems and help sustain photosynthesis under heat and water deficit. In a field trial with corn, the application of osmoprotectants allowed reducing irrigation by 20%, buffering much of the yield drop (Agronomy, MDPI, 2022). A review of 25 years of wheat field trials confirms consistent improvements in WUE and nutrient uptake with biostimulants (Frontiers in Sustainable Food Systems, 2025).

A living soil retains more water

The third factor is under our feet. A soil with good structure, stable aggregates and active organic matter retains more available water and releases it more gradually. Microbial activity binds soil particles together, improves infiltration and reduces evaporation. Taking care of soil biology is, in practice, extending the water reservoir available to the crop between irrigations.