Humus content

Runoff Water running down slopes rather than sinking in (again, result of poor humus content) Ex. erosion due to deforestation... 

Total porosity Percentage large pores Soil salinity Soil sodium content Humus content... 

These properties of soils in Steppe ecosystems are favorable to the formation of uppermost humus barrier, where the accumulation of almost all the chemical species occur. The concentration of chemical elements is slightly decreasing downward in soil profile, in parallel with decreasing soil humus content (Figure 2). 

Table 6. The influence of water deficiency on invertebrate biomass and humus content in Steppe ecosystems.

The humus content in Steppe ecosystem soils reflects the total biomass production and humidity. 

Hautala, K., Peravuori, J., and Phihlaja, K. (2000). Measurement of aquatic humus content by spectroscopic analyses. Water Res. 34, 2246-2258. 

Table 3.8. Dependence of humus content (kg/m2) in a lm layer of soil on mean annual temperature and total precipitation amount H(Ta,W).

Laegreid, M., Alstad, J., Klaveness, D., and Seip, H.M. (1983) Seasonal variation of cadmium toxicity toward the algae Selenatrum capricornutum Printz in two lakes with different humus content. Environ. Sci. Technol. 17, 357-359. 

As seen in Table 3.12, the humus content of soils varies within a rather wide concentration range (0.6%-6.6%). However, parameter adjustment is only successful when the protolytic processes of humus are neglected. Consideration of the protonation and deprotonation of aluminol and silanol sites (Chapter 1, Equations 1.54-1.56 Chapter 2, Sections 23-2.5) is sufficient. It is likely caused by the cations of the support electrolyte and the divalent and trivalent (aluminum and ferric) cations dissolved from the soil that react with the acidic functional groups of soil organic matter, limiting the protonation of functional groups (Hargrove and Thomas 1982 Sparks 2003). 

FIGURE 3.9 Sorption of cyanide from Cu(I)-containing solution versus clay and humus content. 

The adsorbed amount of cyanide is proportional to the clay, humic acid, and iron content. It is difficult to tell which soil component is mainly responsible for cyanide adsorption because, in the case of examined samples, clay, humus, and Fe content increase simultaneously. More informative is the three-dimensional diagram, in which the amount of adsorbed cyanide versus clay number and humus content is plotted (Figure 3.9). 

As seen in Chapter 1, Section 1.1.2, soil organic matter is an undefined system, consisting of many components. So, the determination of soil organic content and the study of humic substances are challenging. For practical purposes, the humus content or, more correctly, soil organic matter content, is determined by standard procedures however, the results cannot be considered as absolutely real values, and can only be compared to each other. 

The humus content should he between 1.5 and 4%, and the pH between 5.5 and 6.5. If the humus content is too low, it is advisable to enrich the soil with organic matter (see section on Organic fertilizers for soil conditioning in Chapter 4), and if the pH is too low the soil should be limed with dolomite lime or calcium carbonate (2000 kg/ha). 

Data for soil, sediment, and sludge are also required for successful project completion. Treatability tests should be conducted to identify parameters such as water, alkaline metals, and humus content in the soils the presence of multiple phases and total organic halides that could affect processing time and cost (22). 

A horizon - high humus content, partially leached of soluble minerals (sometimes called the zone of eluviation)... 

The CEC of the soil is determined not only by humus content but by the kind and amount of clay present. The CEC of different clays is of the order of 3-5 meq/100 g for kaolinite, 30-40 meq for illite, and 80-150 meq for montmorillonite. As noted in Table 2, exchange acidities of humic acids usually range from 485 to 870 meq/100 g for fulvic acids, values up to 1400 meq/100 g have been recorded. These comparisons explain why humus can... 

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