Soil penetration resistance and tree root development

Abstract

Current UK guidance suggests that a ‘rootable’ soil profile of at least 1.0 m depth should be sufficient to allow adequate rooting of the majority of tree species in a range of soil types and climatic conditions [Arboricultural Journal (1995) vol. 19, 19–27]. However, there is some uncertainty as to what constitutes a loosened soil profile in terms of penetration resistance. In this study the root development of Italian alder, Japanese larch, Corsican pine and birch was assessed after 5 years of tree growth. These data were compared to penetration resistance measured using both a cone penetrometer and a ‘lifting driving tool’ (dropping weight penetrometer). Tree root number and percentage were significantly reduced by increasing soil penetration resistance measured with both the cone penetrometer (P < 0.050) and the ‘lifting driving tool’ (P = 0.011 and 0.008 respectively). The vast majority of roots were recorded in soils with a penetration resistance of less than 3 MPa (90.7%) with a significant amount in the less than 2 MPa class (70.2%). Root development of Italian alder, Japanese larch and birch all showed a similar pattern, but Corsican pine appeared to be capable of rooting into more compact soils. The ‘lifting driving tool’ can be used as an alternative measure of soil penetration resistance. This equipment is more cost effective, easier to use and capable of measurements at a greater depth than the cone penetrometer. The majority of Japanese larch and birch roots (84.3%) were recorded in soils where it took less than 15 impacts to penetrate one 10 cm soil depth increment. The modelled data also suggest that a penetration resistance of 2 and 2.5 MPa relates to 10 and 15 impacts respectively.

Desirable plant root traits for protecting natural and engineered slopes against landslides

“…and birch (Betula pendula Roth. ; Sinnett et al 2008). Plants may exhibit compensatory growth as they respond plastically to localised areas of compaction, this response varying between species (Bingham and Bengough 2003).…”

Soil compaction impact and modelling. A review

“…The cone resistance also serves as an indicator of the root penetration and root growth capabilities (Materechera and Mloza-Banda 1997). Sinnett et al (2008) reported that a soil having a cone resistance larger than 3 MPa caused a major hindrance for the root penetration of four tree species (Japanese larch, Italian alder, birch, and Corsican pine) in the sandy loam soils as shown in Fig. 5; nearly all roots (90.7%) were present in the soil with a cone resistance class less than 3 MPa.…”

“…5 Mean percentage of roots in each penetration resistance class using the penetrometer; 90.7% of roots are present in penetration resistance class less than 3 Mpa. From Sinnett et al (2008) the soil organic carbon and nitrogen in the soil (De Neve and Hofman 2000). In a laboratory experiment, when silt loam (acid forest soil) was compacted artificially to a bulk density of 1.5 from 1.1 Mg/m 3 , a significant reduction in the carbon mineralization and net nitrification rates was observed after 9 months (Tan and Chang 2007).…”

Use of penetrometers in agriculture: a review

“…This effect is directly associated with the reduction in the availability of water in the soil, soil aeration, and nutrients to plants, along with the increase of soil resistance to root growth (LETEY, 1985;MEDEIROS et al, 2010). Among various methods to determine the state of soil compaction and physical quality, the evaluation of soil penetration resistance (SPR) has been commonly used in experimental studies, not only related to precision agriculture (SILVA et al, 2004;BOTTEGA et al, 2011;CHERUBIN et al, 2011;DALCHIAVON et al, 2011;GIRARDELLO et al, 2011) but also to assessments of management conditions of agricultural areas (GOEDERT et al, 2002;NEIRO et al, 2003;FREDDI et al, 2007;SILVA et al, 2009;CALONEGO & ROSOLEM, 2011;OTTO et al, 2011) and forests (SEIXAS & SOUZA, 2007;SINNETT et al, 2008).…”