Soil microorganisms and the formation of proteoid roots

1974 ◽  
Vol 22 (4) ◽  
pp. 681 ◽  
Author(s):  
BB Lamont ◽  
AJ Mccomb

Proteoid roots are not formed in sterile soil under conditions which would otherwise allow their production. This is attributed to the absence of soil microorganisms rather than to an alteration of chemical components by autoclaving. Water extracts from proteoid roots or their associated soil did not enhance the formation of proteoid roots. High microbial numbers in the surface soil horizons are considered largely responsible for the abundance of proteoid roots in these high organic matter regions. Results of experiments indicate that the formation of proteoid roots is stimulated by soil microorganisms which themselves do not invade the parent root, though the relevant organisms have yet to be identified.

2006 ◽  
Vol 37 (7-8) ◽  
pp. 939-943 ◽  
Author(s):  
Marcos Gervasio Pereira ◽  
Ademar Espindula ◽  
Gustavo Souza Valladares ◽  
Lúcia Helena Cunha dos Anjos ◽  
Vinícius de Melo Benites ◽  
...  

Author(s):  
Sidinei Julio Beutler ◽  
Marcos Gervasio Pereira ◽  
Wagner de Souza Tassinari ◽  
Michele Duarte de Menezes ◽  
Gustavo Souza Valladares ◽  
...  

1989 ◽  
Vol 37 (2) ◽  
pp. 137 ◽  
Author(s):  
PF Grierson ◽  
PM Attiwill

The proteoid roots of Banksia integrifolia are concentrated in the surface soil, forming a dense mat beneath the litter layer. Water extracts of the proteoid root mat contained a significantly greater amount of hydrogen ions, reductants and an unidentified chelating agent, than water extracts of soil beneath the root mat, of the litter layer and of soil from beyond the proteoid root zone. The results are discussed in relation to previously reported production of organic chelates by plants causing solubilisation of soil phosphates. It is suggested the proteoid roots of B. integrifolia chemically modify the soil environment thereby enhancing nutrient uptake.


2009 ◽  
Vol 23 (2) ◽  
pp. 100-108 ◽  
Author(s):  
Dar-Hao Chen ◽  
Zhiming Si ◽  
Mustafa Saribudak

Soil Research ◽  
2000 ◽  
Vol 38 (2) ◽  
pp. 345 ◽  
Author(s):  
G. D. Schwenke ◽  
D. R. Mulligan ◽  
L. C. Bell

At Weipa, in Queensland, Australia, sown tree and shrub species sometimes fail to establish on bauxite-mined land, possibly because surface-soil organic matter declines during soil stripping and replacement. We devised 2 field experiments to investigate the links between soil rehabilitation operations, organic matter decline, and revegetation failure. Experiment 1 compared two routinely practiced operations, dual-strip (DS) and stockpile soil, with double-pass (DP), an alternative method, and subsoil only, an occasional result of the DS operation. Other treatments included variations in stripping-time, ripping-time, fertiliser rate, and cultivation. Dilution of topsoil with subsoil, low-grade bauxite, and ironstone accounted for the 46% decline of surface-soil (0–10 cm) organic C in DS compared with pre-strip soil. In contrast, organic C in the surface-soil (0–10 cm) of DP plots (25.0 t/ha) closely resembled the pre-strip area (28.6 t/ha). However, profile (0–60 cm) organic C did not differ between DS (91.5 t/ha), DP (107 t/ha), and pre-strip soil (89.9 t/ha). Eighteen months after plots were sown with native vegetation, surface-soil (0–10 cm) organic C had declined by an average of 9% across all plots. In Experiment 2, we measured the potential for post-rehabilitation decline of organic matter in hand-stripped and replaced soil columns that simulated the DS operation. Soils were incubated in situ without organic inputs. After 1 year’s incubation, organic C had declined by up to 26% and microbial biomass C by up to 61%. The difference in organic C decline between vegetated replaced soils (Expt 1) and bare replaced soils (Expt 2) showed that organic inputs affect levels of organic matter more than soil disturbance. Where topsoil was replaced at the top of the profile (DP) and not ploughed, inputs from volunteer native grasses balanced oxidation losses and organic C levels did not decline.


2004 ◽  
Vol 35 (9) ◽  
pp. 1015-1024 ◽  
Author(s):  
Anja Miltner ◽  
Hans-Hermann Richnow ◽  
Frank-Dieter Kopinke ◽  
Matthias Kästner

Author(s):  
Ke Rui ◽  
Wang Hongxing ◽  
Tan Yunzhi ◽  
Wang Lehua

Based on orthogonal experimental design, the key solidification controlling technology of Solidified/Stabilized (S/S) sludge with high total organic content (TOC) by cement, lime and metakaolin was explored by macroscopic tests, chemical components measurements and microscopic analysis. The macroscopic tests show that, the permeability coefficient is mainly affected by initial water content and lime content, and the unconfined compression strength is mainly affected by cement content and lime content. The chemical components measurements show that, the solidification effect of S/S sludge with high TOC is controlled by organic matter consumption, and organic matter consumption is determined by the alkaline environment from the cement and lime hydration reactions, which is mainly affect by the initial water content and lime-metakaolin content ratio. The microscopic analysis results show that, lime consumes parts of organic matter while excess lime produces weak Ca(OH)2 crystal fluffy sheet structure, matakaolin produces pozzolanic reactions with cement and lime instead of soil particles, and consumes the weak Ca(OH)2 crystal fluffy sheet structure produced by superfluous lime. The research has confirmed key controlling points of S/S sludge in case of high TOC, which will provide theoretical guidance and technical support for S/S sludge promotion with high TOC.


Soil Research ◽  
2011 ◽  
Vol 49 (4) ◽  
pp. 287 ◽  
Author(s):  
V. Gonzalez-Quiñones ◽  
E. A. Stockdale ◽  
N. C. Banning ◽  
F. C. Hoyle ◽  
Y. Sawada ◽  
...  

Since 1970, measurement of the soil microbial biomass (SMB) has been widely adopted as a relatively simple means of assessing the impact of environmental and anthropogenic change on soil microorganisms. The SMB is living and dynamic, and its activity is responsible for the regulation of organic matter transformations and associated energy and nutrient cycling in soil. At a gross level, an increase in SMB is considered beneficial, while a decline in SMB may be considered detrimental if this leads to a decline in biological function. However, absolute SMB values are more difficult to interpret. Target or reference values of SMB are needed for soil quality assessments and to allow ameliorative action to be taken at an appropriate time. However, critical values have not yet been successfully identified for SMB. This paper provides a conceptual framework which outlines how SMB values could be interpreted and measured, with examples provided within an Australian context.


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