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Are Salts Affecting Your High Tunnel Crops? On-farm Demonstration Update

Posted: December 19, 2011

High salt levels in soils can affect plant yield and cause salt injury including burnt leaf margins and stunted plants. In the field, saline soils are not common in Pennsylvania. But plastic high tunnels keep the rain from flushing nutrients and salts out of the root zone. Extension Educators tested soils in six high tunnels across the state this summer and found three with soil salinity high enough to affect crops.
Photo 1 -- Salt build-up on the soil surface in a high tunnel. Photo J. Esslinger.

Photo 1 -- Salt build-up on the soil surface in a high tunnel. Photo J. Esslinger.

By Tianna DuPont, Lee Stivers, Emelie Swackhamer, John Esslinger, Elsa Sanchez; Penn State Extension

In three tunnels at two farms, soil salt levels were high according to Penn State soil tests and salts were visible on the soil surface in some cases (see photo 1). In all three where soil salt levels were high, growers had used mushroom soil, compost and/or fertigation. Growers had also not removed their high tunnel plastic for any length of time. At one farm, the grower had not noticed a yield reduction, but at the other farm the plants were noticeably stressed and yield was low.

In order to reduce salts in her high tunnel, grower Teena Bailey at Red Cat Farm in Germansville, Pennsylvania, removed the plastic and left the tunnel uncovered all summer. By the end of the summer, salts on the soil surface of beds were no longer noticeable. Interestingly, salts were still noticeable in compacted pathways.

However, a follow up soil test showed that salt levels now at 0.55 mmhos/cm (1:2 soil:water). This is considered only very slightly saline; 0.81-1.2 is considered moderately saline, causing seedling injury and 25-50% yield reduction possible in broccoli and potatoes.

If you think your high tunnel may have soil salinity problems, take a soil test. Penn State Ag Analytical tests for salts are only $5. For more information on soil salinity and how to remediate the problem, go to high tunnel salts facts sheets.