Spatial distribution of maize roots by complete 3D soil monolith sampling

Abstract

The spatial distribution of root length density (RLD) is important for water and nutrient uptake by plants and biomass allocation in the soil. Experimental root assessment is, however, mostly based on methods that encompass only small fractions of the soil volume. The aim of this study was to characterize the three dimensional (3D) spatial distribution of RLD in the soil of a maize crop for plots of 37.5 and 75 cm row spacing. At each plot, a 3D soil monolith of 70×40×30 (=84,000) cm 3 was completely sampled in form of 84 cubic samples of 10 cm edge length. Roots were washed from the soil and RLD was determined using the line intersect method. In 2004, mean RLD values were 0.41 cm cm −3 for narrow and 0.34 cm cm −3 for wide row spacing at row closure (55 days after planting; DAP) and 0.74 cm cm −3 (1.37 cm cm −3 in 2003) for narrow and 0.77 cm cm −3 (0.96 cm cm −3 in 2003) for wide row spacing at tasseling (104 DAP). The CV values for RLD of 48% to 72% in 2004 were first higher for wide than for narrow row spacing but at the later growth stage (tasseling) lower for wide than for narrow. For individual vertical soil slices, CV values for RLD were about 40-60%, irrespective of the orientation of the slice. The results suggest that RLD was related mainly to the spatial location and the plant row structure, and not governed unambiguously by SBD or SWC. The spatially distributed maize root data suggest that variability of RLD parallel to plant rows is not negligible. Any simplified use of 1D or 2D vertical samples at separate locations may lead to erroneous estimations of RLD profiles.

Root morphology and effects on soil reinforcement and slope stability of young vetiver (Vetiveria zizanioides) plants grown in semi-arid climate

“…In this study, the block excavation method produced results for root distribution with depth similar to the results obtained via the direct shear test on rooted samples and, therefore, the block excavation was considered to be useful. However, for future studies and where more detailed root 3D distribution in the soil is needed as a part of root system characterization, a complete 3d soil monolith sampling (Kuchenbuch et al 2009) may be more applicable.…”

The Optimal Lateral Root Branching Density for Maize Depends on Nitrogen and Phosphorus Availability

“…Competition for phosphorus may be less important than for nitrate , as phosphorus depletion zones are usually less than 3 mm (Ge et al, 2000) while those for nitrate may be of several centimeters. Given that root length densities in maize average around 2 cm cm 23 (Anderson, 1988;Kuchenbuch et al, 2009), it is much more likely that roots compete for the same nitrate source than for the same phosphorus source. LRBD may increase competition for nutrients by placing lateral roots closer together.…”

Connecting the dots between computational tools to analyse soil-root water relations

“…Structural root information can be obtained using either destructive sampling, such as core sampling [76] , monolith excavation [77] , trenches [78] or root crown excavation [79] , or nondestructive ones, such as minirhizotrons [80] . None of these techniques allows for direct reconstruction of the root system, but rather extract synthetic metrics such as a root length density profile, or root crown data (angles, numbers etc.).…”