Plant Parameter Response to Compaction

ABSTRACT: All densities greater than settling density caused a decrease in shoot biomass and root biomass. However, the reduction in shoot dry biomass was greater than that in root dry biomass. The sensitivity of various plant parameters to subsurface compaction varied considerably with plant spicesPlant growth response to subsurface compaction is not only a function of plant type, but also depends on the parameter measured. For alfalfa, the most sensitive parameter to subsurface compaction was tertiary branch production while the least sensitivewas leaflet width for smooth brome grass the most sensitive parameter was shoot dry biomass while the least sensitive was leaf length. The number of tillers was among the least sensitive parameters. For both plant species and soil types, plant height was a relatively insensitive parameter, contrary to common assumptions. Response curves of all parameters to subsurface compaction were generally linear. The effect on specific plant parameters and hence economic costs of soil compaction can be estimated from simple empirical equations. Threshold bulk density values limiting plant growth are a function of soil type, plant type as well as plant parameter measured.