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Some Growth Responses of Tomatoes to Soil Compaction¹

ABSTRACT

Compression of soil reduces the size and arrangement of soil air spaces. When this process is carried beyond certain limits it results in an overall inhibition of some of the physiological processes of plant growth.

A greenhouse experiment was designed to determine some of the effects of reduced soil air spaces on growth of tomatoes. Three soils—Yolo fine sandy loam, Salinas clay loam, and Sacramento clay—were compressed hydraulically into 1-gallon cans to air spaces varying from 42 to 2%. Percentage of germination, velocity of emergence, blossoming, rate of growth, and yield data were taken. Results showed that compacting soil to a certain density increased percentage of germination, but that compression beyond this point seriously reduced the percentage of germination. Compacting the soil increased the time required for seedlings to emerge. Blossoming was delayed as density increased for all three soils tested. Growth curves were plotted for some densities on the soils with the maximum rate of growth occurring at different plant ages, depending on soil air space. Reduced air space retarded growth in all three soils as measured by total height and the weekly change in height.

The relationship between soil air space and total plant height was plotted. A curvilinear regression was found to be highly significant. Optimum air space for maximum height was calculated to be about 30%.

¹ Joint contribution from the Departments of Vegetable Crops and Soils and Plant Nutrition, University of California, Davis. Paper presented before Div. VIII, Crop Science Society of America, at Lafayette, Ind., Aug. 5, 1958.

² Assistant Olericulturist, Assistant Professor of Soils, and Assistant Olericulturist, respectively.

Received for publication June 16, 1958. Accepted for publication December 29, 1958.