Roots soil modification

Some plants can alter the immediate environment around their roots by exuding materials that change soil acidity. This enhances, by three or more orders of magnitude, the solubility of such essential elements such as iron. These plants have a finely tuned biofeedback control that enhances soil fertility precisely at the root surface without altering the rest of the soil. This, then, minimizes the energy cost to the plant of soil modification (Olsen et al., 1981). Root crops and rhizosphere bacteria secrete acids into the soil solution to raise the solubility of solid-phase phosphates (highly pH dependent) in their immediate neighborhoods (Russell, 1961). 

Plants may be affected by indirect modifications of the environment. Soil acidification, for example, can cause the leaching of nutrients, and the release of toxic aluminum. These effects may operate together to produce nutrient deficiencies or imbalances to plants. High soil concentrations of aluminum may prevent uptake and utilization of nutrients by plants.Increased availability of aluminum in soils has been implicated as a cause of forest declines in both Europe and the United States, possibly through the toxic effects on small feeder roots 14),... 

ATPase and specific modification of root cell membrane permeability directly mediated by low-molecular-weight (<5000 Da) fulvic acid-like compounds deriving from native soil organic matter (54-56) (see also Chap. 5). 

Water is modified by soil when added as either rain or irrigation [2], The modifiers are plants, plant roots, organic matter, organic matter decomposition products, carbon dioxide and other gases in the soil atmosphere, and dissolved inorganic compounds, commonly salts. Of particular importance is the change in pH that accompanies this modification of water. Thus, components obtained from soil by added extraction water will be significantly different from... 

The observed ozone-induced growth reductions of roots could result from (a) a direct toxic effect of ozone on the root, (b) an ozone modification of the foliage metabolism which alters the quantity and/or quality of metabolites translocated to the roots, or (c) an alteration in soil chemistry. 

Smucker, A. J.M. Soil Environmental Modifications of Root Dynamics and Measurement. Annu Rev Phytopathol... 

Sarkar, A.N., Jenkins, D.A., Wyn Jones, R.G., 1979. Modifications to mechanical and mineralogi-cal composition of soil within the rhizosphere. In Harvey, J.L., Scott-Russell, R. (Eds.), The Soil-Root Interface. Academic Press. 

Most mineral compounds that constitute soil are hydrophilic however, the modification of organic matter coating the soil particles is instrumental for the transformation of these hydrophilic surfaces to hydrophobic soils (Doerr et al., 2000 Mainwaring et al., 2013). SOM is considered to be a byproduct of plant and animal residues at various stages of decomposition, root exudates, cells and tissues of soil organisms, and substances produced by fungal or soil microbial activity (Llewellyn et al., 2004). Attempts to find correlations between the level of SOM and SWR have to date yielded inconsistent results. 

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