Maturity, soil

Humic residues occur in soil, fresh-water and sea-water. In soils these humic materials represent the principal organic residue of mature soils and are recognised as consisting of three principal components ... 

Immature soil samples have S Te values that are indistinguishable from lunar rocks, whereas submature and mature soils have 5 Fe values that are greater than those of lunar rocks, and S Te values are positively correlated with Ig/FeO values (Fig. 12). Lunar regolith samples in general tend to have heavy isotopic compositions as compared to lunar rock samples, as demonstrated by isotopic analyses of O, Si, S, Mg, K, Ca, and Cd (Epstein and Taylor 1971 Clayton et al. 1974 Russell et al. 1977 Esat and Taylor 1992 Humayun and Clayton 1995 Sands et al. 2001 Thode 1976). The origin of isotopic compositions that are enriched in the heavy isotopes has been presumed to reflect sputtering by solar wind and vaporization, where preferential loss of the lighter isotope to space occurs. In contrast to previous isotopic studies, the Fe isotope compositions measured in the Lunar Soil Characterization Consortium samples can be related to a specific phase based on the positive correlation in Ig/FeO and 5 Fe values (Fig. 12). 

Harada, Y. and Inoko, A. (1980) The measurement of the cation exchange capacity of composts for the estimation of the degree of maturity. Soil Science and Plant Nutrition 26, 127-134. 

Of course there are many other factors involved in flavor of individual varieties of citrus such as seasonal variation, time of harvest or maturity, soil type, rootstock, geographical considerations, etc. 

In general, minerals in sedimentary and meta-morphic rocks contain ferrous iron (Velde, 1985) which is destined to become iron oxide under conditions of weathering. Oxidation under surface conditions has a tendency to produce iron in the ferric state. Most often the process takes iron out of the silicates and puts it into an oxide phase. In the uppermost layers of mature soils, iron oxide and various silicates, usually non-iron-bearing, are produced. In silicates containing iron, the majority is in the ferric state. The extent of the transformation of iron oxidation state is a rough measure of the maturity of the soil. In the extremely weathered soils one finds only ferric iron and aluminum oxides and hydroxides. These soils are typically red. 

In practice, however, it seems that much of the Hg contained within soils and weathered rock is more or less firmly associated with solid phases. This can be shown to extend from simple sorption to structural incorporation within oxidate minerals. The manner of the association between Hg and organic matter has been discussed by Jonasson (1970). The question of adsorption is a rather grey area and, whilst it is clear that it plays a very significant role in soil experiments (e.g., Andersson, 1979), it seems that in mature soils the Hg is held rather more firmly. (This is apart from discrete mineral hosts deriving from sulphide oxidation.) It is possible that, as a simple adsorbent ages, the associated Hg may enter the structure, becoming a "residual" element effectively removed from the dynamic weathering cycle. 

In a mature soil, the balance of humus is maintained by the continued synthesis of new material as part of the old is mineralized consequently, the chemical nature of the humic substances remains constant over time. The humus of each soil may have its own characteristic equilibrium composition, both with regard to chemical nature and composition. 

Young or immature soils are those that have been little weathered and so are in a changing, unstable state. Profiles of such soils may show minimal physical or chemical differentiation from the surface down to bedrock. Older or more mature soils tend toward steady-state conditions. The soil profiles of mature soils have developed subhorizontal layers called soil horizons. From the surface downward these are termed O, A, E, B, C, and R horizons (Table 7.3). Frequently, soil scientists further subdivide individual horizons on a basis of textural and color differences within them. Figure 7.2 is an example of such subdivision for a soil developed on loess. 

The samples were prepared by adding 100 grams of plastic sample to 600 grams of mature soil compost in a 5-liter glass jar. The mature compost, 2-3 months old, had a pH of 8.7, ash content of 35%, and Carbon/Nitrogen (C/N) ratio of 10. The C/N ratio was calculated based upon carbon dioxide and ammonia measurements taken with the Sol vita instrument on the compost at the beginning of the test. Solvita is an easy-to-use test that measures both carbon dioxide (CO2) and ammonia (NH3) levels in the soil and also indicates a Maturity Index value. The index is useful for maturity level of the compost soil (Solvita Test Kit 2013). The blank compost had a Solvita overall maturity index of 7... 

NORSTADT F.A. ajid McGALLA T.M, 1971. Effects of patulin on v/heat gro m to maturity. Soil Science, 111, 236-243. 

As the science of indoor air quality has matured, indoor air professionals have realized that many indoor air contaminants and the associated health effects are linked to specific types of buildings and their characteristics. For example, radon is primarily an indoor air concern in homes because of the ease with which it can be transported inside residential construction from the soil beneath. On the other hand. Sick Building Syndrome (SBS) primarily afflicts office building occupants who experience acute health and comfort effects that appear to be linked to time spent in a specific building. 

The condition of any soil represents a stage in the changing process of soil evolution. Soils develop, mature and change with the passage of time. Whereas the time required for a true soil to develop from the parent rock of the earth may be thousands of years, rapid changes can result in a few years when soils are cultivated, irrigated, or otherwise subjected to man s manipulation. The type of soil that develops from the parent material will depend upon the various physical, chemical and biological factors of the environment. 

Gum Arabic (GA) or Acacia gum is an edible biopolymer obtained as exudates of mature trees of Acacia Senegal and Acacia seyal which grow principally in the African region of Sahe in Sudan. The exudate is a non-viscous liquid, rich in soluble fibers, and its emanation from the stems and branches usually occurs under stress conditions such as drought, poor soil fertility, and injury (Williams Phillips, 2000). 

For wheat plants grown to maturity under irrigation (43) in a soil of neutral pH (44), one can calculate that a mature wheat plant (yield 13.2 g d m [grams of dry matter)] with a Mn concentration of 42 mg/kg took up 556 pg of Mn [i.e., (556/55) X 2 microequivalents of Mn], If ascorbic acid (M, a = 176), or another reducing agent of similar molecular weight and C content is assumed to be the... 

Several studies have indicated that the species diversity of indigenous soil communities will influence the species composition of ectorhizosphere populations (176). On mature roots, seasonal successions may be observed as the soil microbial activity varies with temperature, water content, nutrition, and root exudation. Acero et al. (177) found that the composition of alder (Almis) rhizosphere populations alternated between one dominated by Bacillus spp. in autumn and winter and one dominated by Pseudomonas spp. in spring and summer. 

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