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%.
Potato plants were grown 3 different years in noncompacted, moderately compacted, and severely compacted soils. Changes in yield and quality of tubers were measured against different levels of N and P and against soil moisture tension.
Total and U. S. No. 1 tuber yields were affected adversely by compacted soil. Tuber deformity was confined to angular development conforming to the shape of adjacent clods. Second growth and growth cracks in tubers were of no consequence. No consistent change in specific gravity was found.
Neither yield nor quality of the tubers was enhanced by use of N higher than 180 pounds per acre. Addition of P had no appreciable effect. Soil P reserves were high.
Tuber yield and quality in all soils were best when the soil moisture tension was near 0.5 atm. At a lower tension (0.2 atm) enlarged lenticels were more prevalent, and at a higher tension (0.7 atm) the yield and percent of U. S. No. 1 tubers diminished in severely compacted soil. Without proper control of the soil moisture regime in compacted soils, loss in tuber yield and quality could be accentuated.
Neither changes in fertilizer nor irrigation practices alleviated the adverse effects of soil compaction on potato yield or quality.
Synopsis
Yield of tomatoes was not significantly reduced following severe soil compaction but yield and quality of potatoes were lowered. Equipment operated over the soil in the fall when soil moisture is high caused soil compaction in the upper 6‐inch profile but this compaction tended to be alleviated during the winter months.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.