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With the addition of an equal volume of 0.02 M to the soil suspension that was prepared for the water pH, the final soil-solution ratio is 1:2 0.01 M . A 20-g soil sample is mixed with 20 mL of reverse osmosis (RO) water (1:1 w:v) with occasional stirring.
Soil acidification is the buildup of hydrogen cations, which reduces the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid , such as nitric acid , sulfuric acid , or carbonic acid .
Water with excess H 3 O + ions is called acid (pH < 7), and water with excess OH – ions is called alkaline or rather basic (pH > 7). Soil moisture with pH < 4 is called very acid and with pH > 10 very alkaline (basic). H 2 CO 3 (carbonic acid) is unstable and produces H 2 O (water) and CO 2 (carbon dioxide gas, escaping into the atmosphere).
The soil bulk density of cultivated loam is about 1.1 to 1.4 g/cm 3 (for comparison water is 1.0 g/cm 3). [48] Contrary to particle density, soil bulk density is highly variable for a given soil, with a strong causal relationship with soil biological activity and management strategies. [ 49 ]
The pH range is commonly given as zero to 14, but a pH value can be less than 0 for very concentrated strong acids or greater than 14 for very concentrated strong bases. [2] The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. [3]
CEC is the amount of exchangeable hydrogen cations (H +) that will combine with 100 grams dry weight of soil and whose measure is one milliequivalent per 100 grams of soil (1 meq/100 g). Hydrogen ions have a single charge and one-thousandth of a gram of hydrogen ions per 100 grams dry soil gives a measure of one milliequivalent of hydrogen ion.
Topsoil is composed of mineral particles and organic matter and usually extends to a depth of 5-10 inches (13–25 cm). Together these make a substrate capable of holding water and air which encourages biological activity.
The activity of soil is the ratio of the plasticity index to the clay size fraction. If activity is less than 0.75, the soil is inactive. If activity exceeds 1.4, then the soil is termed active. If activity lies within the above values, then the soil will be moderately active. [10]