Residual effects of a slant-legged subsoiler on some soil physical conditions and the root growth of spring barley

Abstract

SummarySoil disturbance caused by a slant-legged subsoiler (Trade name, ‘Paraplow’) and the duration of its effect was investigated in an experiment comparing long-term direct drilling with shallow tine cultivation and mouldboard ploughing. The ‘Paraplow’ significantly reduced soil strength, measured by cone resistance, to the depth of cultivation (33–35 cm) for up to 20 months, after which soil recompacted. The ‘Paraplow’ increased the volume of soil with cone resistance < 1·5 MPa by 52% within its working depth, compared with an equivalent depth of undisturbed soil. Contour diagrams of cone resistances clearly illustrate the patterns of soil loosening caused by the ‘Paraplow’.Measurements on soil cores (73 mm diameter × 50 mm) show that the ‘Paraplow’ did not appear to increase significantly the volume of macropores (> 60 μm) in direct-drilled soil, nor did it reduce the bulk density in the top 5 cm as effectively as the mouldboard plough.The root density of spring barley, measured at the beginning and end of tillering, was significantly increased within the horizon disturbed by the ‘Paraplow’ but below the depth of loosening there were no differences. This improvement of root growth probably resulted from an increase in the number of large pores (which could not be measured adequately in the soil cores), as well as the reduced soil strength. Better drainage of the soil loosened with the ‘Paraplow’ suggested that macroporosity was improved. The need to sample large volumes of soil to detect changes in bulk density and macroporosity is stressed.

Direct drilling compared with ploughing for winter wheat grown continuously and the effects of subsoiling

“…A cultivation treatment which improves root growth as in this experiment in 1984 might suggest that some deterioration in structure has occurred in the untilled soil, but if the root system in the latter is still large enough to meet the nutrient demands of the crop and its water requirements so that an equivalent yield is given, no serious deterioration has taken place. This is in marked contrast to the results obtained with spring barley on the same soil type (Hipps & Hodgson, 1988).…”

Shallow mechanical loosening of a soil under dairy cattle grazing: Effects on soil and pasture

“…The high variability of results from soil core samples found in this study are not unusual in loosening studies, especially when measurements are taken at various distances away from slots created by loosening implements (Ide et al 1984;Owen 1988;Hipps & Hodgson 1988;Hill 1990;Harrison et al 1994). The spatial variation in soil conditions caused by loosening, and the small volumes of soil and low replications inherent in coring methods, have often produced variable data (Ellington 1986;Johnson et al 1989;Holloway & Dexter 1991).…”

Effects of tillage practices on water consumption characteristics and grain yield of winter wheat under different soil moisture conditions

“…Mechanical subsoil loosening (subsoiling) can be used to reduce soil strength beneath the plough layer, and has been shown by several investigations to increase root penetration (Marks and Soane, 1987;Hipps and Hodgson, 1988;Olesen and Munkholm, 2007). However, the physical effects of subsoiling often do not last more than 1-2 years, after which the plough pan must be reestablished (Hipps and Hodgson, 1988;Tessier et al, 1997). Our previous research has also shown that the 1-year subsoiling plus 2-years of strip rotary tillage helped to increase wheat yield and water use efficiency (Chu et al, 2010).…”