What factors should be considered for the depth at which soil samples are collected?

1 Distribution: According to the distribution of soil type and crop planting varieties, sampling is carried out according to high, medium and low soil fertility. Generally, 150-300 mu (different areas can be determined according to the situation) to take a mixed sample of cultivated layer, and at least 3-4 mixed agrochemical soil samples are collected for the main agricultural soil species in each demonstration village.

The sampling points are distributed in a zigzag or serpentine pattern, and should be as uniform and random as possible. The soil base map should be used to determine the sampling plots and sampling points, and mark them on the map to determine the survey sampling route and scheme.

2. Sampling location and depth: According to the thickness of the cultivated layer, determine the sampling depth, and the general sampling depth is 0-20 cm.

3 Sampling season and time: The location and time of collection of the backbone agrochemical soil samples should be consistent with the soil area represented by the soil backbone agrochemical samples in the second soil census, so as to compare the changes of soil nutrients before and after. The collection time of soil samples was also consistent with that of soil backbone agrochemical samples in the second soil survey.

If the collection time of the second soil census cannot be ascertained, it will be collected after autumn harvest and before winter sowing and fertilization.

4. Sampling method and quantity: The agrochemical soil sample adopts the multi-point mixed soil sample collection method, and each mixed agrochemical soil sample is composed of 20 sample points. The distribution range of sample points is not less than 3 acres (each place can be determined according to the situation).

The depth and weight of the soil at each point should be uniform, and the proportion of the upper and lower layers of the soil sample should also be the same. The sampler should be perpendicular to the ground and sink into the soil to the specified depth. Samples are done using stainless steel, wood, bamboo, or plastic utensils.

Do not touch metal utensils and rubber products during sample handling and storage to prevent contamination.

Each mixed sample is generally about 1kg, if too many samples are collected, the excess soil can be discarded by the "quarter method".

5. Sample number and file record: make sampling records: soil sample number, sampling location and latitude and longitude, soil name, sampling depth, previous crop and yield, sampling date, sampling person, etc.

The sampling depth is generally 0 20cm, the orchard is 0 40cm, the soil nitrate nitrogen or inorganic nitrogen content is determined, and the sampling depth should be determined according to the main root distribution depth of different crops and different growth periods. The depth and amount of soil taken at each sampling point should be uniform, and the proportion of the upper layer and the lower layer of the soil sample should be the same.

1. The method of determining the sampling depth.

If you only have a general understanding of the soil pollution status, you only need to collect 0 20cm of tillage layer soil for cultivated land planted with general crops; For cultivated land planted with fruit crops, 0 60 cm of tillage layer soil was collected.

If you want to know the depth of soil contamination, you should stratify sampling by soil profile level.

A typical natural soil profile is divided into A (surface, humus leaching layer), B (sublayer, sedimentary layer), C layer (weathered parent rock layer, parent layer) and bottom rock layer. Groundwater in saline-alkali land is higher and should be sampled to the water table;The mountainous soil layer is thin, and samples can be taken to the regolith layer of the parent rock.

2. Reasons for multi-point collection of mixed soil samples:

Because soil is an inhomogeneity, the factors that affect it are intricate. There are natural factors including topography (height, slope), parent material, etc.;Human factors include tillage, fertilization, etc., especially the uneven distribution of soil nutrients caused by tillage and fertilization, such as strip application and hole application, ridge planting, deep tillage and other measures, all of which can cause local differences.

All of this illustrates the prevalence of soil heterogeneity, which makes it necessary to collect mixed soil samples from multiple sites, and then sample them after they are fully mixed to increase their representativeness and scientific validity.

Laboratory workers can only be responsible for the results of the analysis of the samples they send in, and if the samples sent do not meet the requirements, then any precision instruments and skilled analytical techniques will be meaningless.

The soil sampler can truly meet the requirements of full-layer, equal and convenient soil sampling, and solve the difficult problem of accurate collection of soil samples for soil and fertilizer work such as soil testing and formula fertilization and soil monitoring. The provincial soil and fertilizer workstation has designated the sampler as a special tool for soil sampling in the province's soil testing formula fertilization, soil monitoring and cultivated land fertility investigation and quality evaluation projects. It is an ideal tool for soil sampling in environmental protection, geology and other industries.

The types of soil samplers can be divided into:

1. Power (gasoline) soil sampler: conventional soil sampling saves manpower, and the sampling depth is 2 meters.

2. Manual soil sampler (set): a variety of drill bits, suitable for collecting standard samples.

3. Soil heavy metal sampler: the sampling diameter is 5cm, the length of a sampling is 20cm, and the single-point sampling volume is about 1kg.

4. Soil organic matter sampler: sampling length 20cm. The standard configuration is equipped with a sampling depth of 5m

5. Non-disturbance sampler: soil volatile organic matter sampling is used with gas chromatography.

6. Grab-type sludge miner: 3L, counterweight brick, sludge sampling;5L, standard 20m rope, sludge sampling.

7. Piston columnar sludge miner: suitable for water depth: 5m, conventional analysis and sampling, heavy metal analysis and sampling, and layered sampling.

8. Gravity columnar sludge: sampling depth: 50m, sampler weight: 50kg

9. Root soil sampler: 304 stainless steel, actual sampling height: 10cm, columnar soil, depth can be customized.

10. Heart-shaped soil sampler: 304 stainless steel, depth can be equipped with extension rod.

11. Undisturbed soil extraction drill: material: 304 stainless steel of the whole body; Wall thickness:

3mm;Overall length: 1m (optional length: ; Drill length:

25cm (optional drill length: 25cm-50cm); Drill bit diameter: 50mm (optional drill bit diameter:

mm, etc.) 12, stainless steel twist drill: material: 304 stainless steel; Wall thickness: 6mm; Overall length: 1m; Drill length: 30cm; Drill diameter: 50mm (optional mm).

13. Stainless steel Dutch drill: 304 stainless steel, wall thickness: 3mm, total length: 1m, drill length: 30cm, drill bit diameter: 50mm

14. Soil sampler: undisturbed drill bit.

15. Soil sampling drilling rig: sampling depth: 1-10 meters (optional), standard 2m

When sampling soil, commonly used tools are earth drills, ring knives, shovels, and moreShovel

Dirt drillsSampling has little damage to the soil, and the soil can be taken in layers.

Ring knivesIt is often used to take undisturbed soil.

ShovelsIt is often used to excavate profile pits in order to collect profile samples or entire specimens.

Electric soil samplers, root samplers, soil solution samplers, etc. are also basic tools for soil sampling. In addition, TOP also provides a soil sampling toolbox, which can be disassembled and stored in the box, which is easy to carry, and is equipped with tools such as tape measures and wrenches.

Soil sample collection equipment in the broad sense mainly includes a series of tools, such as:

1) Tools include shovels, shovels, circular earth drills, spiral earth drills, bamboo chips and tools suitable for special sampling requirements.

2) Equipment includes GPS, compass, camera, film, tape measure, aluminum box, sample bag, sample box, etc.

3) Stationery includes sample labels, sampling record sheets, pencils, folders, etc.

4) Safety protective equipment includes work clothes, work shoes, safety helmets, medicine boxes, etc.

5) Vehicles for sampling.

The soil sample collection equipment in the narrow sense mainly refers to soil sampling drills, soil solution samplers, soil samplers, soil bulk weighers and other tools.

The depth of field crop sampling is generally o-20cm, and if it is a deep-rooted crop, it can be harvested to o-30cm; The sampling depth of the orchard is o-40cm.

Summary. What are the requirements for collecting soil samples and what should be paid attention to?

In order to ensure the accuracy and reliability of sampling, there are some requirements and precautions:

Pro, 1Sampling tools: Clean stainless steel or plastic tools should be used, and tools containing metal should be avoided to avoid contamination.

Pro, 2Sampling location: Appropriate sampling sites should be selected according to the research purpose, and areas that may be polluted, such as chemical plants, roadsides, etc. At the same time, it is also necessary to pay attention to the representativeness of sampling points and try to avoid interference between sampling points.

Pro, 3Sampling depth: In general, soil samples are collected to a depth of 0-20 cm, but can also be adjusted according to the needs of specific studies.

Pro, 5Concealment of sampling bags: Collected soil samples should be placed in a clean and sealed sample bag to avoid contact with the air in the outside cave hall to prevent the loss of moisture and nutrients from the samples.

Pro, 6Labeling and records: Each sampling bag should be labeled with a Naqiao label, indicating the sampling point, the depth of the vertical sample of the harvested eggplant, the sampling date and other relevant information, and make detailed records for later analysis and research.

In addition to the above requirements and precautions, there are some additional extensions:- Sampling time: The collection time of soil samples should avoid extreme weather such as rainfall, strong winds, and high temperatures as much as possible to ensure the stability of the sampling environment.

Sampling frequency: Depending on the purpose and needs of the study, single sampling or multiple sampling can be carried out to obtain more comprehensive soil information. - Sampling Order:

When collecting from multiple sampling sites, the collection should be carried out in the prescribed order to avoid cross-contamination. - Cleaning of sampling tools: After each soil cavity sample, the sampling tools should be thoroughly cleaned to avoid contamination between different sampling points.

When collecting soil samples, it is necessary to pay attention to the requirements of sampling tools, sampling locations, sampling depths, sampling volumes, sampling bags, labels and records to ensure the accuracy and reliability of the sampling process. In the case of the same spine, other factors such as sampling time, sampling frequency and sampling sequence can also be considered according to the specific research needs of the root nucleus. Hope the above can be helpful to you!

Summary. Hello dear, if we are measuring the index of air-dried soil (such as measuring soil organic matter), because the conversion of the final value of organic matter is to convert air-dried soil to dry soil, so the determination of soil moisture content at this time needs to use air-dried soil.

After collecting the soil, determine what does not require fresh soil?

Hello dear, after collecting soil, fresh soil is not needed to measure organic matter. Measuring the organic matter of the soil requires air-dried soil, so fresh soil is not needed.

Hello dear, if we are measuring the index of air-dried soil (such as measuring soil organic matter), because the conversion type of the final value of organic matter is to convert the air-dried soil into dry soil, so the determination of soil moisture content at this time needs to use air-dried soil.

Summary. Principle. After sulfur dioxide is absorbed by the formaldehyde buffer solution, a stable hydroxymethanesulfonic acid addition incantation compound is formed.

Sodium hydroxide was added to the sample solution to decompose the addition compounds, and the released sulfur dioxide reacted with pararosaniline hydrochloride and formaldehyde to form a purple-red compound, which was determined by spectrophotometer at 577 nm according to the color shade. The main interferants of this method are nitrogen oxides, ozone and some heavy metal elements. The addition of sodium sulfamate can eliminate the interference of nitrogen oxides; Leaving it for a period of time after sampling allows the ozone to decompose on its own; The addition of phosphoric acid and disodium salt of cyclohexanediaminetetraacetic acid can eliminate or reduce the interference of certain metal ions.

The presence of 50 ugca mg, fe, fe, ni, plasma and 5 ug divalent manganese ions in 10 ml of sample does not interfere with the assay.

After collecting the soil, determine what does not require fresh soil?

Hello, glad for your question. Once the soil has been collected, fresh soil is not required to determine the water content.

If we measure the index of air-dried soil (such as measuring soil organic matter), because the conversion of the final value of organic matter is to convert air-dried soil to dry soil, so the determination of soil moisture content at this time needs to use air-dried soil.

On April 16, 2022, China successfully launched an atmospheric environment monitoring satellite in Taiyuan.

Measuring the organic matter of the soil requires air-dried soil, so fresh soil is not needed.

On April 16, 2022, at 2:16 Beijing time, the world's first atmospheric environment monitoring satellite with carbon dioxide laser detection capabilities was launched at the Taiyuan Satellite Launch Center in Shanxi, China.

Multi-domain quantitative remote sensing.

How the permanganate index works.

Potassium permanganate oxidizes some organic and inorganic reducing substances in the sample, adds excess sodium oxalate to reduce the remaining potassium permanganate after the reaction, and then uses potassium permanganate standard solution to drip back the excess sodium oxalate, and the titration of the virtual rent and final type of the sample is judged according to the color change of the poor answer, and the permanganate index in the sample is calculated by calculation.

Formaldehyde absorption rose aniline spectrophotometric principle.

Wait a little kiss

Principle. After sulfur dioxide is absorbed by the formaldehyde buffer solution, a stable hydroxymethanesulfonic acid addition incantation compound is formed. Sodium hydroxide was added to the sample solution to decompose the addition compounds, and the sulfur dioxide released reacted with pararosaniline hydrochloride and formaldehyde to form purple-red compounds, which were determined by spectrophotometer at 577nm according to the color shade.

The main interferants of this method are nitrogen oxides, ozone and some heavy metal elements. The addition of sodium sulfamate can eliminate the interference of nitrogen oxides; After sampling, it can be placed for a period of time to destroy the slag and make the ozone decompose itself; The addition of phosphoric acid and disodium salt of cyclohexanediaminetetraacetic acid can eliminate or reduce the interference of certain metal ions. The presence of 50ugca mg, fe, fe, ni, plasma and 5ug divalent manganese ions in 10 ml of sample did not interfere with the determination of Hengzi.