Soil Management and Grass Species Effects on the Hydraulic Properties of Shrinking Soils

Abstract

In this study, we explored the effect of the roots of different forage grasses on soil hydraulic properties at the plot scale. To achieve this, we set up a field experiment in which six different grass cultivars were grown on replicated field plots at North Wyke, UK. We used tension infiltration measurements to assess soil hydraulic properties and structure. These measurements were made over two consecutive seasons. Measurements of shrinkage, water repellence, and the water release characteristic on soil samples taken from the North Wyke site were also made. We also wanted to compare the effects of different grasses on soil structure with the effects of differences in soil management; we therefore made tension infiltration measurements on fallow soil, permanent grassland, and arable land on a long‐term experiment at Rothamsted, Harpenden, UK. Our data showed that the saturated hydraulic conductivity of the capillary matrix of the soil sown with grass depended on the grass species. Grass species affected the characteristic pore size estimated from tension infiltration data. At the Rothamsted site, we were able to infer that the development of macropore structure can be ranked grassland > arable > fallow (from the greatest to the least amount of macropores). In the North Wyke site, all the grass plots showed evidence of a macropore structure, consistent with the grassland site at Rothamsted, but there did not appear to be any variation between grass species. We concluded that changes to soil structure were probably due to physical rearrangement of soil particles by shrinkage.

A novel grass hybrid to reduce flood generation in temperate regions

“…Poor infiltration of water into soil is sometimes explained in terms of biologically induced water repellence21, but we found no difference (P = 0.117) in the wettability (as measured with the capillary rise method22) for soils in the different grass plots20. We conclude that the differences in infiltration (Figure 1) and soil water content of the profile (Figures 3 and 4) are due to differences in the spatial organization of soil, commonly referred to as soil structure.…”

“…We carried out field based tension infiltration measurements on four occasions (May 2007, October 2007, May 2008 and July 2008), where the flux of water into the soil was measured at a range of negative pressures (−2, −1.5, −1.0, −0.5 and 0 kPa)20. This technique measures the hydraulic properties of the surface soil.…”

Shear strength of aggregates compared with bulk soil of two haploxerolls from Chile

“…The differing behaviour between the different uses for the STG and MPC soils, whereby non-tilled STG soil had lower bulk density than tilled while MPC soil did not show any differences between the different managements, may be related to their soil mineralogy (Barzegar et al, 1995). The 2:1 clay type in the Mapocho Soil Series induces greater shrinkage-swelling by drying-wetting, which may encourage pedoturbation and thus increase the translocation of materials and pore occlusion, leading to an increase in bulk density at the NT site (Gregory et al, 2010;Pathak et al, 2011). Therefore, when comparing the pore size distribution in both Soil Series for the same management regime, the NT samples showed significantly higher fast draining porosity for STG than MPC soil, besides significantly reduced wilting point porosity.…”

Designing Grass Cultivars for Droughts and Floods

“…Details of this project, SuperGraSS funded by a BBSRC are described elsewhere (Macleod et al 2007;Gregory et al 2010;Humphreys et al 2010). The species and species hybrids used comprise six cultivars They were: Lolium perenne, (Lp) cv AberStar, Lolium multiflorum, (Lm) cv AberEpic, Festuca pratensis, (Fp) cv Bf993 (all 2n = 2x = 14), Festuca arundinacea (Fa) cv Dovey (2n = 6x = 42), and Festulolium cultivars Lp × Fp cv Prior, and Lm × Fa cv 99-1 (both 2n = 4x = 28).…”

“…The cultivars were grown as four replicated 10 × 3 m hydrologically-isolated plots, with rainfall and run-off measured over the course of 31 rainfall events that subsequent to an initial six months establishment phase, spanned all changes in grass growth over the two year field study (as in Gregory et al 2010). …”