Inceptisols and Andisols

Diagnostic Horizons

In Inceptisols the beginning of profile development is evident and some diagnostic features are present. However, the well-defined profile characteristics of soils thought to be more mature have not yet developed. The epipedon in most Inceptisols is an ochric although plaggen or weakly exposed mollic or umbric epipedon may be present. The subsurface of Inceptisols may include duripans, fragipans, calcic or gypsic. Inceptisols whow more significant profile development than Entisols.

Productivity

Inceptisols are probably the most important soil order in the low land rice growing areas of Asia. The natural productivity varies considerably. For example, those found in the Pacific Northwest of United States are quite fertile and provide some of the world's best land for producing wheat. On the other hand, some having low organic matter in Southern New York and Northern Pennsylvania are not naturally productive.

Characteristics

In Inceptisols the beginning of profile development is evident and some diagnostic features are present. However, the well-defined profile characteristics of soils thought to be more mature have not yet developed. They show more significant profile development than Entisols.

Distribution

Inceptisols are widely distributed throughout the world and constitute more than 9% if the world's land area. They are found in most climatic and physio-graphic conditions. They are prominent in mountainous areas, especially in the tropics.

Inceptisols are found in each of the continents. Inceptisols of humid regions are called Udepts extend from Southern New York through central and Western Pennsylvania, Eastern Ohio. Xerepts also dominate an area extending from southern Spain through Central France to Germany. Wet Inceptisols or Aquepts are found in areas along Amazon and Ganges river.

Suborders

Anthrepts (Human-made, high phosphorus, dark surface Inceptisols)

Aquepts (wet Inceptisols)

Cryepts (very cold Inceptisols)

Udepts (Inceptisols of humid climate)

Ustepts (Inceptisols of semiarid)

Xerepts (Inceptisols of dry summers and wet winters)

Andisols

Diagnostic Horizons

Andisols are volcanic ash soils. It's epipedon is Melanic. Melanic is a surface diagnostic horizon that has a high organic content and dark color. The accumulation of organic matter is quite rapid due largely to its protection in aluminium-humus complexed.

 Productivity

Some Andisols are very productive for wheat and timber production. But the problem is the phosphorus retention capacity of this order is very high. Proper management of plant residues and fertilizers can usually overcome this difficulty. The high content of organic matter and high content of amorphus result in fluffy soils that can be easily tilled.

Characteristics

Andisols are usually formed on volcanic ash. They are commonly found near the volcano source or in areas downwind from the volcano, where a sufficient;y thick layer of ash has been deposited during eruptions. The principal soil forming process has been the rapid weathering of volcanic ash to produce amorphus or poorly crystallized silicate minerals such as allophane and imoglite and the iron oxy-hydroxide, ferrihydrite. Like the Entisols and Inceptisols, Andisols are also young soils usually having developed for 5,000 to 10,000 years.

Distribution

Andisols are found in areas where significant depths of volcanic ash and other ejecta have accumulated. Globally, they make up less than 1% of the soil area. However, in the Pacific rim area they are important and productive soils that support intensive agriculture. Andisols having a Udic soil moisture regime are widely cultivated in Japan, producing enough food to support very high population densities. Cryand andisols are found in Canada and Russia. Torrand Andisols are found in Mexico and Syria.

Suborders

Aquands (Wet Andisols)

Cryands (Cold Andisols)

Torrands (Hot and dry Andisols)

Udands (Andisols of humid regions)

Ustands (Moist or dry Andisols)

Vitrands (Volcanic glass)

Xerands (dry summers, moist winters)