Soil Salinity in High Tunnels

Drought stress on tomato leaves. Soil salinity can cause
increased susceptibility to drought stress in plants. 
Photo: Long Island Horticultural Research & Extension Center

Soil salinity can occur in high tunnel production due to some of the characteristics unique to this type of growing system. High tunnels are often used as a season extension tool, meaning that they are in production for a longer period of time and managed more intensively than a typical field. This management can include fertilizer applications, irrigation, and heavy traffic leading to compaction and poor drainage, all of which contribute to salt buildup in the soil.

The other major difference between tunnel and field production with an impact on soil salinity is that the ground under tunnels is protected from the elements, most notably precipitation. In a field situation salts would have more opportunity to be flushed through the system by rainfall, while tunnels aren’t able to take advantage of this type of natural cleansing. 

Soil salinity is a concern for a number of reasons including that plants in saline soils are more susceptible to water stress, which is particularly prevalent in a year with so little excess water around anyway. Saline soils can also lead to salt injury in plants and adverse affects on soil structure. It is important to monitor the salt levels of your soil and take preventative measures to avoid excess buildup. Some strategies for preventing or managing saline soils include utilizing mulch to reduce evaporation from the soil, deep tillage, and exposing the soil to rain by removing the plastic from the tunnel. As you start to think about coming to the end of the production cycle, it might be a good time to employ some of these strategies or plan preventative measures for next season.

For more information, check out Perennia’s factsheet: Soil Salinity in Nova Scotia High Tunnels.