sweet corn, respectively. Yield reduction in transplanted cabbage (evaluated in 1993 only) was 29%. In a controlled environment greenhouse experiment using the same soil type and similar compaction treatment as the field study, compaction caused a reduction in total biomass production of 30% and 14% in snap bean and cabbage, respectively, while cucumber and sweet corn showed no significant response. The growth reductions of snap bean and cabbage in the greenhouse could not be attributed to compaction effects on soil water status, leaf turgor, nutrient deficiency, or net CO, assimilation rate of individual leaves. Root growth of sweet corn was least restricted by the compacted soil layer. The contrast between our field and greenhouse results indicates that the magnitude of yield response to compaction in the field was often associated with species sensitivity to secondary effects of compaction, such as prolonged flooding after rainfall events, reduced nutrient availability or uptake, and prolonged or more severe pest pressure.
be a good predictor of the effect of mechanical impedance and substrate pore size, because data obtained by Baligar and Nash (1978) and Wiersum (1957) demonstrate that a root is only able to penetrate a pore that has a diameter exceeding that of a
et al., 2015 ; Svistoonoff et al., 2007 ). There is also substantial evidence that supports the role of soil compaction or mechanical impedance on root growth in plant species ( Lipiec et al., 2012 ; Oussible et al., 1992 ; Taylor and Brar 1991
Ferrini, 2006 ). They are also susceptible to mechanical impedance in the soil ( Materechera et al., 1992 ); thus, low bulk density can improve posttransplant root growth. Bulk density was generally lowest and chemical properties more favorable for PB and
The response of roots to mechanical impedance has intrigued horticulturists, plant biologists, and substrate physicists for at least two centuries ( Araki and Iijima, 2001 ; Atwell, 1993 ), whereas the model of root growth as a function of multiple
States range from 15 to 40 mol·m −2 ·d −1 compared with 25 to 60 mol·m −2 ·d −1 in the southwestern United States ( Korczynski et al., 2002 ). Mechanical impedance of light by glazing materials and greenhouse support structures reduces transmission of
nature of the mechanical impedance to seedlings by soil surface seals Austral. J. Soil Res. 3 45 54 Bernard, R. 2005 Garden-type vegetable soybean varieties. Illinois Agricultural Experiment Station, Urbana, IL Burris, J.S. Edje, O.T. Wahab, A.H. 1973
Effects of four compaction remediation methods for landscape trees on soil aeration, mechanical impedance, and tree establishment J. Environ. Hort. 13 64 71 Dirr, M.A. 1998 Manual of woody landscape plants 5th ed Stipes Publishing Champaign, IL Fonteno, W