Plant exudates improve the mechanical conditions for root penetration through compacted soils

Oleghe, Ewan; Naveed, Muhammad; Baggs, Elizabeth M.; Hallett, Paul D.

doi:10.1007/s11104-017-3424-5

Cited by 55 publications

(56 citation statements)

References 46 publications

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“…Carminati et al () revealed the influence of mucilage on the water holding capacity of the soil immediately around the root, and its implications for hydraulic continuity around the root system was demonstrated by (Moradi et al, ). In compacted soils, the influence of plant derived exudates have been highlighted to improve mechanical conditions for root penetration (Oleghe, Naveed, Baggs, & Hallett, ). Carminati and Vetterlein () proposed the concept of rhizosphere plasticity to help understand the bimodal hydraulic responses found at the root–soil interface under different bulk soil moisture conditions.…”

Section: Introductionmentioning

confidence: 99%

The role of plant species and soil condition in the structural development of the rhizosphere

Helliwell

Sturrock

Miller

et al. 2019

Plant Cell & Environment

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Roots naturally exert axial and radial pressures during growth, which alter the structural arrangement of soil at the root–soil interface. However, empirical models suggest soil densification, which can have negative impacts on water and nutrient uptake, occurs at the immediate root surface with decreasing distance from the root. Here, we spatially map structural gradients in the soil surrounding roots using non‐invasive imaging, to ascertain the role of root growth in early stage formation of soil structure. X‐ray computed tomography provided a means not only to visualize a root system in situ and in 3‐D but also to assess the precise root‐induced alterations to soil structure close to, and at selected distances away from the root–soil interface. We spatially quantified the changes in soil structure generated by three common but contrasting plant species (pea, tomato, and wheat) under different soil texture and compaction treatments. Across the three plant types, significant increases in porosity at the immediate root surface were found in both clay loam and loamy sand soils and not soil densification, the currently assumed norm. Densification of the soil was recorded, at some distance away from the root, dependent on soil texture and plant type. There was a significant soil texture × bulk density × plant species interaction for the root convex hull, a measure of the extent to which root systems explore the soil, which suggested pea and wheat grew better in the clay soil when at a high bulk density, compared with tomato, which preferred lower bulk density soils. These results, only revealed by high resolution non‐destructive imagery, show that although the root penetration mechanisms can lead to soil densification (which could have a negative impact on growth), the immediate root–soil interface is actually a zone of high porosity, which is very important for several key rhizosphere processes occurring at this scale including water and nutrient uptake and gaseous diffusion.

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Section: Introductionmentioning

confidence: 99%

The role of plant species and soil condition in the structural development of the rhizosphere

Helliwell

Sturrock

Miller

et al. 2019

Plant Cell & Environment

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“…[13] state that MRP values up to 2500 KPa are considered low and show little limitation on root development. High MRP values increase resistance to root growth [19], reduction in total soil porosity by reducing water storage and restriction of gas flow [20]. The large spatial variability of the mechanical resistance to penetration presents a series of implications for root and shoot growth [21].…”

Section: Resultsmentioning

confidence: 99%

Soil Mechanical Resistance Penetration after Fifteen Years with Previous Crops and Tillage Systems and Productivity of Green Corn Cob in Northeast Brazil

Pedrotti

Filho

Assunção

et al. 2019

JEAI

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Conservation systems for less soil movement and when associated with previous crops may reduce the effects of soil compaction. The objective of this work was to evaluate soil mechanical resistance penetration (MRP) in different cropping systems associated with previous corn crop after fifteen years. The experimental design was composed of experimental strips with subdivided plots, combining three soils management systems: CC- conventional cultivation, MC- minimum cultivation and NT- no-tillage, and four species of crops antecedent to maize for the production of commercial ears of green corn. In the determination of soil MRP, the electronic penetrometer (FALKER model SoloTrack PLG 5200) was used, with readings up to a depth of 400 mm. The results showed that there was a significant effect on the MRP values of the soil when submitted to the different cropping systems and previous crops at the end of fifteen years. The lowest MRP values were located in the superficial layers in the CC and MC. The NT cultivar system showed higher MRP values, at depth 0-100 mm. At conditions of tableland, after fifteen years, it was observed that the NT system provides better corn productivity levels combined with lower MRP values along the profile.

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“…Seed exudate was extracted from chia (Salvia sp.) by the same method described in Oleghe, et al (2017).…”

Section: Tablementioning

confidence: 99%

“…Gravimetric water content, water sorptivity and cone penetration measurements were repeated. The samples were then rewetted and dried again to -50 kPa, followed by compression to 600 kPa on the same mechanical test frame using approaches described in Oleghe et al (2017).…”

Section: Mechanical and Hydrological Measurementsmentioning

confidence: 99%

Residues with varying decomposability interact differently with seed or root exudate compounds to affect the biophysical behaviour of soil

et al. 2019

Self Cite

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Plants have a large impact on the physical behaviour of soil, partly due to seed and root exudates that alter mineral:organic matter associations. In this study we explored how the decomposability of residues in soil interacts with seed or root exudate compounds to influence microbial respiration, mechanical behaviour and hydrological properties. Sandy loam and clay loam soils were amended at a rate of 40 t ha-1 with ground green barley (7.13 mg C g-1), barley straw (7.26 mg C g-1) or poultry manure (5.22 mg C g-1), and either chia seed exudate at 1.84 mg C g-1 soil or root exudate compounds at 14.4 mg C g-1 soil. On cores packed to 1.3 g cm-3 , uniaxial compression, penetration resistance, water sorptivity, water retention and porosity were measured at time 0, after 14 days of incubation at 20 o C, and then after subjecting incubated soils to three cycles of wetting and drying to simulate weathering. These time increments and weathering were intended to simulate a newly germinated seed or tip of a root, through to a more mature system. Application of seed and root exudate increased carbon dioxide (CO 2) emissions from 0.31 ± 0.01 to 15.11 ± 0.71 μg C-CO 2 g soil-1 hour-1 for the sandy loam soil and from 0.171 ± 0.01 to 10.56 ± 0.78 C-CO 2 g soil-1 hour-1 for the clay loam soil. There were large changes in soil physical properties caused by seed or root exudate amendment coupled with residues, their decomposition and weathering. After incubation and weathering, soils with added seed or root exudates and their interactions with organic residues were more mechanically stable, as measured by penetration resistance (22 to 58% increase) and compression index (25 to 43% decrease) compared to soils amended only with organic residue. Water sorptivity and porosity diminished with the addition of the exudate. Exudates in combination with organic residues better protected soils against structural destabilization by increasing particle cementation, and decreasing rapid wetting and porosity.

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Plant exudates improve the mechanical conditions for root penetration through compacted soils

Cited by 55 publications

References 46 publications

The role of plant species and soil condition in the structural development of the rhizosphere

The role of plant species and soil condition in the structural development of the rhizosphere

Soil Mechanical Resistance Penetration after Fifteen Years with Previous Crops and Tillage Systems and Productivity of Green Corn Cob in Northeast Brazil

Residues with varying decomposability interact differently with seed or root exudate compounds to affect the biophysical behaviour of soil

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