What kind of soil is alkaline soil? What is Alkaline Soil?

Alkaline soil is soil with a soil pH greater than 7.

The alkaline reaction of the soil is reflected when the concentration of oh- ions in the soil solution exceeds the concentration of h+ ions, and the concentration of oh- ions in the solution shows the strength of the alkalinity of the soil, or the pH value.

The larger, the more alkaline it is. Soil pH value less than 7 is acidic soil, and soil pH value greater than 7 is alkaline soil.

The soil acidity and alkali in China are different, and the north of the Yangtze River is mostly neutral and slightly alkaline soil; As far as cities are concerned, there are more than 50 cities with different degrees of saline-alkali soil distribution, such as Tianjin, Dezhou, Panjin, Lianyungang and other cities.

Causes of the formation of alkaline soils:

Alkaline soil is formed by the comprehensive influence of natural conditions and soil intrinsic factors, among which arid climate and abundant calcium are the main causes. Excessive application of lime and irrigation of alkaline effluent, as well as seawater impregnation, are also responsible for the formation of some alkaline soils.

Dry and semi-arid climate zones, with atmospheric precipitation.

Alkali metals and alkaline earth metals released by weathering rocks and minerals are much lower than the amount of evaporation.

The simple salts cannot completely migrate to the earth, but accumulate in large quantities in the soil and its groundwater.

Most of these simple potassium, sodium, calcium, and magnesium salts are their carbonates or bicarbonates.

Because they are controlled by the bias pressure of the large amount of CO2 released by organisms), these salts can be hydrolyzed to produce OH ions, which allow the soil to evolve in an alkaline direction. This is the most direct and primary cause of the formation of alkaline soils.

What kind of soil is "acidic soil" for raising flowers? What soil is "alkaline soil"? The distinction is simple!

The properties of soil are divided into three main categories:

1.Scattering: There is no bond or weak bond between the particles, there are a large number of pores, and it can be permeable to water and air.

2.Multiphase: Soil is often a three-phase system composed of solid particles, water and gas, and the changes in quality and quantity between the three phases directly affect its engineering properties.

3.Natural variability: Soil is a multi-mineral assemblage formed by the evolution of a long geological history in nature, which is complex, uneven, and constantly changing over time.

The engineering properties of soil are mainly as follows:

Looseness: After the excavation of natural soil, its volume increases due to looseness, although it is vibrated and tamped, it still cannot recover its original volume, which is the looseness of soil.

Permeability: Refers to the ease with which water flows through pores in the soil.

Compressibility: After the loose soil is transported and filled, it will be compressed, and the compressibility of the general soil is expressed by the compressibility rate of the soil, and the compressibility rate of the soil is related to the dry density of the soil.

Moisture content: is the ratio of the mass of water in the soil to the mass of solid particles, expressed as a percentage.

Compactness: It is to indicate the degree of compactness of the soil, and the dry density of the soil is used in engineering to reflect the relative degree of compactness.

1.Natural water content

The natural moisture content of soil indicates the degree of dryness and wetness of the soil, and refers to the ratio of the weight of water in the soil to the weight of soil particles in the natural state. The greater the water content of the soil, the more humid the soil, and the more unfavorable it is for construction.

2.Conversion of looseness to earthwork volume.

Looseness: After the soil is excavated, the tissue is destroyed, the volume increases, and even if it is compacted, it cannot recover its original volume, which is called the looseness of the soil, which is expressed by the looseness coefficient.

Looseness coefficient: the volume in the loose state after excavation is called the imaginary volume, and the volume that is not compacted after backfilling is called the loose filling volume. The ratio of the volume of earthwork in various states to the volume in the natural state is called the looseness coefficient of soil.

According to the looseness coefficient, the volume of soil in various states can be converted according to the quota provisions.

Earthwork volume conversion table.

Imaginary square volume, natural compactness volume, tamping body volume, loose filling volume.

Loess is a more acidic soil.

The mineral composition of loess includes detrital minerals and clay minerals, with the former accounting for more than 70%. Among the detrital minerals, it mainly refers to light minerals with less density, accounting for more than 90%, quartz is the most, feldspar is second, and there are some carbonate minerals (calcite, dolomite, etc.). The clay minerals in loess are mainly mica, kaolinite and montmorillonite.

The existence of these minerals makes the loess have the characteristics of adsorption, expansion and contraction, which affects the engineering properties of the loess. Carbonate minerals often play a cementing role, so that the loess particles often exist as agglomerates in the case of natural structure. After encountering water, the collapsibility of the loess is often enhanced due to the destruction of the aggregates cemented by soluble salts.

Therefore, some people believe that the presence of carbonates in loess is one of the reasons for the collapse of loess.

Although the detrital minerals of loess-like soil are mainly quartz and feldspar, the content of unstable minerals is low, and they are generally strongly weathered and associated with nearby bedrock.

3 5 The sub-districts are mainly distributed in Qinghai, Ningxia, Gansu and Henan provinces, covering an area of 10,000 square kilometers4km km². The upper reaches of the small watershed are generally "streams" and "palms", with relatively flat terrain and few channels. There are gullies in the middle and lower reaches.

The loess hilly and gully area is the most serious area of soil erosion in China and even in the world. Soil erosion has not only become the main problem that plagues the sustainable development of agriculture and the people's poverty alleviation and prosperity in the region, but also brings a series of ecological and environmental problems to the lower reaches of the Yellow River.

Alkaline soil refers to soil with soil pH value greater than 7; That is, the concentration of hydroxide ions in the soil solution is greater than the concentration of hydrogen ions, which practically refers to the soil with a pH value above it. Generally, it includes three types: calcareous soil, saline soil and alkaline soil.

The formation of alkaline soils is controlled by a variety of factors, and regional differences are significant. Salinization and alkalinization often occur at the same time. Due to the continuous expansion of the intensity of human interference, the vegetation on the grassland has also been seriously damaged, and these places are mostly coastal and belong to the wetland category, and the salinity in the seawater will also affect the salinity content of the land, resulting in serious salinization of the land and serious harm.

Alkaline soil refers to soil with soil pH value greater than 7; Saline soil is a general term for various salinized soils, saline soils, alkaline soils and alkaline soils, which are generally referred to as saline-alkali soils. When the salt content of the surface layer exceeds chloride) or 2% (sulfate), it is extremely harmful to lawn plants, only a very small number of salt-tolerant wild plants can grow, and even no grass grows in serious cases, this kind of soil is called saline soil.

If the soluble salts contained in the surface layer are mainly alkaline salts, so that the soil is strongly alkaline, and the percentage (alkalinity or sodium) of the total amount of exchange cations (alkalinity or sodium) of pH and exchange sodium ions exceeds 5%, it is called alkaline soil, and when the degree of alkalinity is greater than 20%, it is called alkaline soil.

In northern China, the climate is dry, with little precipitation, and the soil is generally alkaline. In hot and dry conditions, soluble salts accumulate on the soil surface as soon as the water table rises to within a few metres of the surface. It mainly occurs in plains where rivers are overflowing, lowlands near lakes and depressions where drainage accumulates.

The saline soil in China is mainly distributed in the river alluvial plains in the arid and semi-arid inland areas such as the north of the Huai River, the northwest and the Qinghai-Tibet Plateau. High concentration of salt causes "physiological drought" in turfgrass, interferes with the normal absorption and metabolism of nutrients by roots, and causes the comprehensive toxic effect of salt.

Extended information: The acidity and alkalinity of soil, also known as soil reaction, is often expressed by pH and is an important chemical property of soil. In addition to directly affecting seedling grabbing, plant growth and development, and microbial activities, soil acidity and alkalinity have a greater impact on many biochemical properties in the soil, especially on the availability of a variety of nutrients, and will also affect the physical properties of the soil.

Improvement of alkaline soils. The improvement of strongly alkaline soils is a difficult task. On the one hand, it is necessary to consider reducing the pH of the soil solution, but in the process of reducing the pH, the exchanged Na+ or Mg2+ often deteriorates the physical properties of the soil, and people often use gypsum (CaSO4 2H2O) to improve the alkaline soil.

On the other hand, the addition of organic fertilizers and acidic fertilizers (such as superphosphate) also has a certain improvement effect.

What kind of soil is "acidic soil" for raising flowers? What soil is "alkaline soil"? The distinction is simple!

Hello, the soil is easy to agglomerate and is acidic soil. How to identify if the soil is acidic or alkaline:

1. You can go to the chemical store or measuring instrument sales department to buy pH test paper to test the acidity and alkalinity of the soil solution, the soil pH value is less than 7 is acidic soil (the smaller the number, the stronger the acidity), and the pH value greater than 7 is alkaline soil (the larger the number, the stronger the alkalinity). 2. Look at watering: after watering, acidic soil infiltrates quickly, does not bubble white, and the water surface is muddy; After watering the alkaline soil, the infiltration is slower, the water surface bubbles white, foams, and sometimes there is a layer of white alkaline material around the pot.

3. Look at the soil color: acidic soil is generally darker in color, mostly black-brown, while alkaline soil is mostly white, yellow and other light colors. In some saline-alkali areas, there is often a layer of alkaline white powder on the soil surface.

4. Look at the surface plants: when mining flower soil in the wild, you can observe the plants growing on the surface, and the soil where wild rhododendrons, pines, and cedar plants grow is mostly acidic soil; And grow Tamarix.

The soil in millet and sorghum is mostly alkaline soil. 5. Look at the texture: the acidic soil has a loose texture and strong air permeability; Alkaline soil is hard, easy to form lumps, and has poor aeration and water permeability.

6. By feel: acidic soil has a "soft" feeling in the hand, after letting go, the soil is easy to spread out and not easy to agglomerate; Alkaline soil has a "hard" feeling in the hand, and it is easy to agglomerate and not fall apart after letting go.

Generally speaking, loess is neutral, it is neither acidic nor alkaline. However, China has a vast land and abundant resources, and the specifics depend on the situation in different places and regions. If acidic fertilizer is applied to the alkaline soil all the time, the acidity of the soil will become greater over time, and the alkalinity of the soil will become greater.

This is mainly due to man-made or natural variations.

Soil pH is used to measure the strength of soil acid-base reaction, mainly determined by the concentration of hydrogen ions and hydroxide ions in the soil solution, the general pH value is between the neutral soil, the following is acidic soil, the above is alkaline soil, loess belongs to neutral soil.