Use of brackish water for the irrigation of potato crops

Faced with increasing uncertainty on freshwater supplies, this field lab explored the use of brackish water (slightly saline) in irrigation of Maris Piper potatoes

Innovative Farmers Field Lab 2020

Agriculture in eastern England is facing ever increasing pressures on freshwater resources, particularly in areas near the coast where saline intrusion of water courses is set to rise in the coming century. However, irrigation is essential not only for healthy growth, but also for control of common scab on potato tubers.

This field lab was instigated at the request of Nene Potatoes Ltd, one of whose members also hosted the trial, which was funded through the Innovative Farmers programme.

The trial measured a range of key crop yield parameter, levels of scab, and also a range of soil properties.

Brackish water irrigation

Much of the surface water (for abstraction) in the region remains brackish for large parts of the year, and there is also a shallow saline groundwater interface. If growers could utilise slightly more brackish water for irrigation, it would reduce their reliance on freshwater.  Although there is a large body of work on salinity tolerance of conventional crops, much of the literature stems from trials conducted in more arid and semi-arid parts of the world. As such, there is limited data available for looking at the salinity tolerance of typical UK potato varies in UK soils and climatic conditions. 

Trickle/Drip Irrigation

Trickle irrigation can be a much more efficient use of water than overhead delivery on silt soils. It could also avoid the problems of delivery into the ridge in hydrophobic soils and leaf scorch from a brackish application. In the trial  brackish water treatments were applied via drip irrigation and compared with an adjacent overhead delivery system.

Results

The trial results showed that even at the maximum level of brackish water used (4,000 ppm), there were no impacts to crop yield measures or on the levels of common scab on tubers. Measurements of soil responses, including  penetration resistance readings, infiltration readings, and soil respiration (CO₂) readings did show some contrasts between plots, although none were found to be significantly different. Soil salt levels had been reduced to pre-trial levels by the following spring. 

Read other information on irrigation or common scab