Soil and Crop Quality Under High Tunnel

Soil and Crop Quality Under High Tunnel

Summary

In 2007 sample analysis was completed and survey data compiled. The value of this research was dependent on grower participation with the questionnaire in conjunction with soil sample collection at their farms. More than one hundred growers took part in the study. Academic writings and public presentations catering to horticulture producers of the Great Plains will be prepared with the research findings.

Objectives/Performance Targets

• Qualify soil quality factors influenced during horticultural production under high tunnels.Measure indicators of soil quality under high tunnels and in adjacent fields on farms in the Kansas, Missouri, Nebraska and Iowa.

  Suggest management alterations that may improve soil quality.

Accomplishments/Milestones

• Compiled questionnaire data.Tested indicators of soil quality in preliminary experiments at Kansas State University Research and Extension Centers at Olathe and Haysville.

  Measured soil quality in soil collected from farms using indicators selected from preliminary experiments.

  Studied survey and analysis results to consider relationships between management, perception of soil quality, and soil quality indicator measurements.

Impacts and Contributions/Outcomes

An oral presentation was made at the annual American Horticulture Society meeting in July 2007. A summary of survey responses about high tunnel management and preliminary soil quality findings were received with interest.

A similar presentation was well received at the Great Plains Vegetable Growers Conference in January 2008. The main subject was surface salinity in soils under high tunnels and salinity management options.

Looking forward to 2008:
We hope to present research findings this year in a thesis, journal articles, a report mailed to the farmers who participated in the study, postings on the hightunnels.org website, and through presentations at grower conferences and field days.

Example of Research Results:

Summary of soil salinization under high tunnels –
We found that soil salinity is significantly affected by the presence of a high tunnel in preliminary studies at Kansas State University Research and Extension Centers at Olathe and Haysville, KS. Electrical conductivity in soil extracts was low (EC < 1 dS/m) in all research plots, but it was about 0.4 dS/m higher under high tunnels than in indentically managed adjacent field plots.

Soil salinity was measured in over sixty grower high tunnels that had been in use from 2 to12 years, and in adjacent fields. Neither field nor high tunnel soils were found to be saline in the upper 15 cm. Analysis did show salt accumulation in the soil surface 5 cm of high tunnels. This is likely related to the transfer of salts to the soil surface by capillary water movement caused by surface evaporation. In high tunnels sampled, 26% had an EC greater than 2 dS/m, and 3 % and an EC greater than 4 dS/m in the upper 5 cm. This surface salinity can be deleterious to seed germination and transplant productivity if not suitably managed. Soil salinity in high tunnels was not statistically correlated to years in location, organic management, or amount of organic matter added.

Our conclusion was that a high tunnel structure increases the chance of surface salt accumulation. Changes in irrigation management will prevent productivity loss in most high tunnel situations. Salinization is not inevitable in high tunnels in place for long durations.

Collaborators: