The parent material conditions for the formation of black soil, the type of parent material formed i

The parent material is the passage of rock minerals from the surface layer of the earth's crustWeatheringThe weathering products formed are the material basis for the formation of the soil and the skeleton that makes up the soil.

It is not only different from soil, but also has a profound impact on the formation of soil and fertility development, many traits of the parent material are inherited to the soil, and the physical and chemical properties of the parent material are changed, forming the upper part of the weathered crust with loose structure.

Parent factors play an important role in soil formation. Because, on the one hand, it is the basic material that constitutes the mineral part of the soil, and on the other hand, it is the ** of the mineral nutrient elements of plants. Therefore, the parent material is a direct participant in the process of soil formation.

Soil-forming parent material refers to the most basic primitive material in the soil, which has not undergone obvious physical and chemical changes, and it is the foundation of various organic and inorganic substances in the soil. The types of soil-forming parent materials include rock parent material, aeolian parent material, water parent material, and biological parent material.

Rock parent material refers to the parent material formed by weathering, erosion and physical fragmentation of rocks composed of minerals. The type and content of minerals in the rock parent material determine the chemical properties and fertility of the soil.

Aeolian parent material refers to the parent material formed by the action of wind, which is mainly distributed in deserts, potato springs and other areas. The mineral content in the aeolian parent material is low, and the soil fertility is poor.

Hydrosedimentary parent material refers to the parent material formed by hydraulic action, which is mainly distributed in rivers, lakes and other areas. The mineral content in the hydrocumulated parent material is higher, and the soil fertility is better.

Biological parent material refers to the parent material formed from organic matter such as plant and animal remains, feces, humus, etc. Biological parent material contains high organic matter and nutrients, and is the type of parent material with better soil fertility.

Different types of soil-forming parent materials have different effects on soil properties and fertility, so it is necessary to select appropriate land types according to the actual situation in land use and agricultural production.

There are two types of residual parent material and transport parent material.

According to the action of different external forces, it is divided into the following categories:

Flood parent material is weathered rock clastic material. When the cavity of the flash flood section is opened, it is washed away and transported to the piedmont plain, where it is gradually deposited and formed as the impact of the flood decreases.

Alluvial parent material is an weathered detrital material that is formed by the sedimentation of river water on both sides of the river after years of erosion and transportation. It is the main substance that makes up the vast plains.

The parent material is the weathering product of the upper part of the slope, which is formed by the combination of gravity and small flowing water formed by rainfall, and is formed in the middle of the slope or at the foot of the mountain. It is commonly found in high-rise areas in mountainous areas and foothills.

The lacustrine parent material is a sediment formed by the transition between low-lying land and lake depression, unlike alluvial parent material, which is affected by flowing water and is a static water deposit. Most of them are distributed in low-lying basins, among which the parent material formed by oxbow lake is also the macrochromatic parent material of the lake circle.

The sedimentary parent material is related to the sea, and under the action of seawater, loose materials accumulate along the coast. Most are stacked horizontally (one on top of the other).

The type of soil-forming parent material of soil in China, in general; In the area south of the Qinling Mountains and the Huaihe River, the weathered crust formed by the weathering of various rocks in situ is mostly the most widely distributed. In the areas north of the first line of the Kunlun Mountains, Qinling Mountains and Shandong hills, the main soil-forming parent material is loess sediment and sandy aeolian deposit, and in the middle and lower reaches of the major river plains, the soil-forming parent material is mainly river alluvium. The parent soil in the plain lake area is mainly lacustrine deposits.

In the alpine and plateau areas, in addition to the in-situ weathering of various rocks, there are also moraines and icy water deposits.

1. Also known as soil parent material, the loose debris formed by the weathering of the surface rock, and the loose weathering formed by the change of physical properties, is the basic original substance for the formation of soil, the material basis for soil formation and the initial element of plant mineral nutrients (nitrogen removal).

2. After the solid large rock becomes debris, it produces pores, which are aerative and permeable. Chemical weathering makes some nutrients soluble salts for plants to absorb. The fine clay particles in the parent material also have the ability to retain nutrients and water.

Therefore, the parent material has preliminary fertility properties, which lays the foundation for biological growth and reproduction and soil formation.

3. According to the formation and transportation of the parent material, it is divided into residual parent material and transport matrix. The latter refers to the parent material deposited after being transported by gravity, hydraulics, wind, glaciers, etc. There are slope parent material, alluvial parent material, aeolian parent material, moraine parent material, etc.

Soil Forming Factors:

1) Parent factors of soil formation.

Weathering breaks the rock, changes the physical and chemical properties, and forms a loosely weathered crust, the upper part of which can be called the soil parent material. If the weathered crust remains in place and forms a residue, it is called residual parent material; If the weathered material is migrated under the action of gravity, flowing water, wind, glacier, etc., to form colluvium, alluvium, marine deposit, lacustrine deposit, moraine and aeolian deposit, etc., it is called the sedimentary parent material. Soil-forming parent material is the first material basis for soil formation and the initial element of plant mineral nutrients (except nitrogen).

The parent material represents the initial state of the soil, which is gradually transformed into a soil for growing plants over a period of thousands of years under the influence of climate and biology. The parent material plays an important role in the physical properties and chemical composition of soil, and this effect is most significant in the early stage of soil formation. As the process progresses, the differences in properties between the parent material and the soil become, but some characteristics of the parent material are always preserved in the soil.

First of all, the type of soil parent material is closely related to soil texture. The weathering resistance of different rock-forming minerals varies significantly, and the order from large to small is roughly as follows: quartz, muscovite, potassium feldspar, biotite, albite, amphibole, pyroxene, abrazine, feldspar, olivine.

Therefore, the soil texture developed on the mafic rock parent material is generally finer, with more silt and clay grains, and less sand grains. The soil texture developed on the acidic rock matrix with higher quartz content is generally coarse, that is, it contains more sand particles and less silt and clay. In addition, the soil developed on the residue and slope sediment contained more rocks, while the soil developed on the flood and alluvial deposits had obvious texture stratification characteristics.

Secondly, the mineral composition and chemical composition of the soil are strongly influenced by the parent material. The mineral composition of different rocks is significantly different, so is the mineral composition of the soil on which it develops. The soil developed on the matrix rock parent material contains more dark minerals such as amphibole, pyroxene, biotite, etc.; The soil developed on acidic rock matrix contains more light-colored minerals such as quartz, orthoclase and muscovite. Other soils such as moraine and loess parent material, clay minerals such as hydromica and chlorite, soil developed on river alluvium are also rich in water mica, and clay minerals such as montmorillonite and water mica are developed on lacustrine deposits.

From the perspective of chemical composition, the content of iron, manganese, magnesium and calcium in the soil on the mafic rock parent material is generally higher than that on the acidic rock parent material, while the content of silicon, sodium and potassium is lower than that on the acidic rock parent material, and the calcium content of the soil on the limestone parent material is the highest. ,9,