Root development of winter wheat in erosion‐affected soils depending on the position in a hummocky ground moraine soil landscape

Abstract

Agricultural soil landscapes of hummocky ground moraines are characterized by 3D spatial patterns of soil types that result from profile modifications due to the combined effect of water and tillage erosion. We hypothesize that crops reflect such soil landscape patterns by increased or reduced plant and root growth. Root development may depend on the thickness and vertical sequence of soil horizons as well as on the structural development state of these horizons at different landscape positions. The hypotheses were tested using field data of the root density (RD) and the root lengths (RL) of winter wheat using the minirhizotron technique. We compared data from plots at the CarboZALF‐D site (NE Germany) that are representing a non‐eroded reference soil profile (Albic Luvisol) at a plateau position, a strongly eroded profile at steep slope (Calcaric Regosol), and a depositional profile at the footslope (Anocolluvic Regosol). At each of these plots, three Plexiglas access tubes were installed down to approx. 1.5 m soil depth. Root measurements were carried out during the growing season of winter wheat (September 2014–August 2015) on six dates. The root length density (RLD) and the root biomass density were derived from RD values assuming a mean specific root length of 100 m g−1. Values of RD and RLD were highest for the Anocolluvic Regosol and lowest for the Calcaric Regosol. The maximum root penetration depth was lower in the Anocolluvic Regosol because of a relatively high and fluctuating water table at this landscape position. Results revealed positive relations between below‐ground (root) and above‐ground crop parameters (i.e., leaf area index, plant height, biomass, and yield) for the three soil types. Observed root densities and root lengths in soils at the three landscape positions corroborated the hypothesis that the root system was reflecting erosion‐induced soil profile modifications. Soil landscape position dependent root growth should be considered when attempting to quantify landscape scale water and element balances as well as agricultural productivity.

Crop growth and soil water fluxes at erosion‐affected arable sites: Using weighing lysimeter data for model intercomparison

“…The low predictability of the observed effects by the single crop models or the MMM within this model exercise might be related to the assumed maximum rooting depth of each soil, as root development in such a specific soil landscape depends on the erosion‐induced soil profile modifications such as horizon thickness, vertical sequence of horizons, and structural development of the horizon (Herbrich, Gerke, & Sommer, 2017). To account for the different potential rooting depths, the rooting depth was adjusted to the soil profile in a second step and ranged from 0.47 at the hilltop to 1.5 m at depression.…”

“…texture, bulk density, continuity of the pore system, soil organic C, and nutrients). The magnitude of these changes is related to spatially distributed intensities of soil erosion by water and tillage (Gerke & Hierold, 2012), the distance to the ground water table (Rieckh et al., 2012), and their combined effect on the above‐ and belowground plant growth and development (Große, 1963; Herbrich, Gerke, & Sommer, 2017; Li, Lobb, Lindstrom, & Farenhorst, 2007). As the simulation results indicate, the average range of the individual crop model simulations and the MMM cannot capture such complex interactions on the variables ET a and NetQ (see Figures 3a and 3b), when using the provided soil hydraulic properties and calibrating on phenology stages only.…”

Reducing topsoil depth decreases the yield and nutrient uptake of maize and soybean grown in a glacial till

“…The negative effects of soil erosion on crop productivity can be attributed to the loss of soil organic carbon and plant nutrients, especially nitrogen (N), phosphorous (P), and potassium (K) (Herbrich, Gerke, & Sommer, 2018; Kaspar et al, 2004). Quinton, Govers, Van Oost, & Bardgett (2010) reported that topsoil erosion decreased 23–42 Tg of N, 2.1–3.9 Tg of organic P, and 12.5–22.5 Tg of inorganic P per year globally.…”

Erosion of topsoil decreases the yield and nutrient uptake of maize and soybean grown in Mollisols

“…The negative effects of soil erosion on crop productivity can be attributed to the loss of soil organic carbon and plant nutrients, especially nitrogen (N), phosphorous (P), and potassium (K) (Kaspar et al, 2004;Herbrich et al, 2018). Quinton et al (2010) reported that topsoil erosion decreased 23-42 Tg of nitrogen, 2.1-3.9 Tg of organic P and 12.5-22.5 Tg of inorganic P per year on the global scale.…”

“…Quinton et al (2010) reported that topsoil erosion decreased 23-42 Tg of nitrogen, 2.1-3.9 Tg of organic P and 12.5-22.5 Tg of inorganic P per year on the global scale. Plants obtain nutrients from soil mainly through roots; however, root growth in the soil vary with soil physical, chemical, and biological properties (Wang et al, 2015;Shinohara et al, 2016;Herbrich et al, 2018). It has been reported that a reduction of topsoil thickness caused by soil erosion results in decreases in soil organic matter (Liu et al, 2003;Srinivasan et al, 2012;Li et al, 2019a;Miao et al, 2019), available nutrients (Bakker et al, 2004;Sui et al, 2013;Xiong et al, 2018) and the effective rooting zone (Graveel et al, 2002).…”