A device and method for rapid in-situ measurement of soil exchangeable nutrients

Abstract

A device and method for rapid in-situ soil nutrient measurement, relating to the field of soil nutrient detection technology, includes a multi-frequency sensor, a soil temperature sensor, and a cloud. The multi-frequency sensor and soil temperature sensor transmit data to the cloud via a wireless terminal (DTU). The device also includes a terminal connected to the cloud via an access point. The multi-frequency sensor and soil temperature sensor are also connected to a power supply. This invention utilizes a device for rapid in-situ soil nutrient measurement and establishes a computational model in the cloud to achieve in-situ soil nutrient measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of soil nutrient detection, and in particular to an in-situ rapid detection device and method for soil exchangeable nutrients. Background Art

[0002] Soil nutrients include both water-soluble and exchangeable nutrients. Soil research often involves measuring exchangeable nutrients, including nitrate nitrogen, ammonium nitrogen, and cation exchange capacity. Exchangeable nutrients are the form of nutrients adsorbed by the electrical double layer within soil clay particles. Their content significantly influences crop growth and yield. Measuring exchangeable nutrients in soil can help assess the soil's fertility capacity and help prevent over- or under-fertilization. Exchangeable nutrient data is also crucial when formulating fertilization plans to optimize the ratios of nitrogen, phosphorus, potassium, and other elements, thereby increasing crop yields and reducing environmental pollution.

[0003] Currently, chemical extraction is the most common method for measuring soil exchangeable nutrients. This involves collecting soil samples in the field and then transferring them to the laboratory for chemical extraction. However, chemical extraction can produce irreversible chemical adsorption; chemical extraction destroys the original soil structure, including texture, bulk density, porosity, and specific surface area; and chemical separation methods produce a water-to-soil ratio that exceeds the maximum ratio in the original soil state. These factors can lead to deviations between measured results and the actual exchangeable nutrients in the soil, resulting in low measurement efficiency. Summary of the Invention

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides an in-situ rapid measurement device and method for soil exchangeable nutrients. By adopting an in-situ rapid measurement device for soil exchangeable nutrients and setting up a calculation model in the cloud, the purpose of in-situ soil exchangeable nutrients is achieved.

[0005] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0006] A device for rapid in-situ measurement of exchangeable nutrients in soil includes a multi-frequency sensor, a soil temperature sensor, and a cloud. The multi-frequency sensor and soil temperature sensor transmit data to the cloud via a wireless terminal DTU. The device also includes a terminal connected to the cloud via an access point. The multi-frequency sensor and soil temperature sensor are also connected to a power supply device. The cloud has the following calculation model:

[0007] FSIC i = ;

[0008] FSIC i =e -kv·Cxi ;

[0009] Among them, FSIC is the frequency scale index characteristic of dielectric function; iis the soil exchangeable nutrient marker, f 土壤 is the frequency value of the soil, f 纯水 is the frequency value of pure water, f 干土 is the frequency value when the soil moisture content is 0%, f 空气 is the frequency value of air, n is the frequency value coefficient; -kv is the sensitive frequency point parameter of the soil index to be measured under multiple spectra; Cxi is the soil exchangeable nutrient index to be measured, including exchangeable nitrate nitrogen content, exchangeable ammonium nitrogen content, adsorbed phosphorus content, exchangeable potassium content, organic matter content, and cation exchange capacity; the cloud has a frequency value coefficient database, which includes soil quality, soil temperature, soil moisture content, and frequency value coefficient.

[0010] Furthermore, the soil types in the database include sandy soil, loamy soil, and clay soil.

[0011] Furthermore, the soil temperature range of the database is 0~50℃, and statistics are divided into sections of every 5℃.

[0012] Furthermore, the soil moisture content in the database ranges from 0% to saturation, and is divided into sections with every 5% volume moisture content.

[0013] Furthermore, the soil moisture content of the database ranges from 0% to saturation, and the moisture content ranges according to soil type are 0%~30% for sandy soil, 0%~45% for loamy soil, and 0%~50% for clay soil.

[0014] Furthermore, the frequency value coefficient n of the database is obtained by using a physical separation method to test the soil frequency data within the corresponding soil quality, soil temperature, and soil moisture content range, and then obtaining the ratio of the test soil frequency data to the soil frequency data under the standard state. After repeating several times and taking the average value, the frequency value coefficient n is obtained.

[0015] The method for rapid in-situ measurement of soil exchangeable nutrients using the device comprises the following steps:

[0016] Step 1: Install the outer tube of the multi-frequency sensor into the soil in situ. Install the soil temperature sensor into the soil to the same installation depth as the outer tube of the multi-frequency sensor. Connect the multi-frequency sensor and soil temperature sensor to the wireless terminal DTU and solar power supply device.

[0017] Step 2: During the test, the test end of the multi-frequency sensor is inserted into the outer tube to collect the frequency value of the soil. The frequency value of the soil and the soil temperature data measured by the soil temperature sensor are uploaded to the cloud through the wireless terminal DTU;

[0018] Step 3: The cloud obtains the soil exchangeable nutrient index to be measured based on the soil frequency value and soil temperature data, the frequency value coefficient database and the calculation model;

[0019] Step 4: The terminal obtains the soil exchangeable nutrient indicators to be measured from the cloud by accessing and displaying them.

[0020] Furthermore, in step 1, the outer tube of the multi-frequency sensor is processed by a vertical ring knife method.

[0021] Furthermore, the installation range of the soil temperature sensor is within a radius of 40-50 cm with the outer tube of the multi-frequency sensor as the center.

[0022] The present invention has the following beneficial effects: By using an in-situ rapid soil exchangeable nutrient measurement device, establishing a frequency coefficient database and calculation model in the cloud, and using a physical separation method to obtain soil exchangeable nutrient indicators based on soil quality, soil temperature, soil moisture content, and frequency coefficients, the present invention can achieve in-situ soil exchangeable nutrient indicators, improve test result accuracy, and enhance testing efficiency. DETAILED DESCRIPTION

[0023] In order to better explain the present invention and facilitate understanding, the present invention is described in detail through specific implementation methods.

[0024] The present invention provides an in-situ rapid measurement device and method for soil exchangeable nutrients. The device includes a multi-frequency sensor, a soil temperature sensor, and a cloud. The multi-frequency sensor and soil temperature sensor transmit data to the cloud via a wireless terminal (DTU). The device also includes a terminal connected to the cloud via an access point. The multi-frequency sensor and soil temperature sensor are also connected to a power supply, which can be a solar power supply. The cloud has the following calculation model:

[0025] FSIC i = ;

[0026] FSIC i =e -kv·Cxi ;

[0027] Among them, FSIC is the frequency scale index characteristic of dielectric function; i is the soil exchangeable nutrient marker, f 土壤 is the frequency value of the soil, f 纯水 is the frequency value of pure water, f 干土 is the frequency value when the soil moisture content is 0%, f 空气Where: -kv is the frequency value of air, n is the frequency coefficient; -kv is the sensitive frequency parameter of the soil indicator under multi-spectral analysis; Cxi is the soil exchangeable nutrient indicator under analysis, including exchangeable nitrate nitrogen content, exchangeable ammonium nitrogen content, adsorbed phosphorus content, exchangeable potassium content, organic matter content, and cation exchange capacity. The cloud maintains a frequency coefficient database, which includes soil quality, soil temperature, soil moisture content, and frequency coefficients. The method for determining the sensitive frequency parameters of the soil indicator under multi-spectral analysis is prior art and can be determined based on the method described in Chinese Patent Application No. 201611209179.7, "A Method for Rapid In-Situ Soil Nutrient Measurement Based on Dielectric Spectroscopy."

[0028] The soil types in the database include sandy soil, loamy soil, and clay soil. The soil temperature range is 0–50°C, with statistics broken down into 5°C increments. The soil moisture content range is 0% to saturation, with statistics broken down into 5% volumetric moisture content increments. Specifically, the moisture content ranges for sandy soil are 0%–30%, for loamy soil 0%–45%, and for clay soil 0%–50%.

[0029] The frequency coefficient n of the database is obtained by physically separating the soil to be tested. This physical separation method is a known technique, such as the physical separation method described in Chinese Patent CN119086221B. The soil frequency data is tested within a range of soil quality, soil temperature, and soil moisture. The ratio of the tested soil frequency data to the soil frequency data under standard conditions is then calculated. This is repeated several times and averaged to obtain the frequency coefficient n. The standard soil frequency data is specifically the soil frequency data obtained under the conditions described in Chinese Patent CN119086221B. Specifically, the frequency coefficient n is obtained by averaging the results after three repetitions.

[0030] More specifically, the frequency value coefficient database is obtained as follows:

[0031] Step 1) Prepare soil columns: Compact the air-dried soil in an in-situ sampling calibrator to obtain soil columns, which are divided into three groups according to sandy soil, loamy soil, and clay soil, and set aside.

[0032] Step 2) Add water to each soil type separately. Use a syringe to slowly add water to the soil column. After each addition, let it stand for 0.5 to 1 hour to allow the water to fully migrate in the soil column and obtain a soil column within the set soil moisture content range. Soil moisture content is added and sampled according to the following soil type and gradient range:

[0033] Sandy soil: 0%~5%, 5%~10%, 10%~15%, 15%~20%, 20%~25%, 25%~30%;

[0034] Loamy soil: 0%~5%, 5%~10%, 10%~15%, 15%~20%, 20%~25%, 25%~30%, 30%~35%, 35%~40%, 40%~45%;

[0035] Clay soil: 0%~5%, 5%~10%, 10%~15%, 15%~20%, 20%~25%, 25%~30%, 30%~35%, 35%~40%, 40%~45%, 45%~50%.

[0036] In the above soil moisture range, the "0%~5%" soil moisture range includes 0% and 5%. In the other soil moisture ranges, the data after "~" are inclusive, and the data before "~" are exclusive.

[0037] Step 3) Place the soil column obtained in step 2) within the set soil moisture content range into an oven, adjust the oven temperature to the set soil temperature range, preheat the oven to the set temperature for 0.5 hours each time, then place the soil column in the oven, place a thermometer in the soil column, and when the soil column temperature rises to the set temperature range, take out the soil column and test the soil frequency of the soil column.

[0038] Set the soil temperature ranges as follows: 0°C to 5°C, 5°C to 10°C, 10°C to 15°C, 15°C to 20°C, 20°C to 25°C, 25°C to 30°C, 30°C to 35°C, 35°C to 40°C, 40°C to 45°C, and 45°C to 50°C. In the above soil temperature ranges, the "0°C to 5°C" range includes 0°C and 5°C. In the remaining soil temperature ranges, the data after "~" are inclusive, and the data before "~" are exclusive.

[0039] Step 4) Divide the measured soil frequency by the soil frequency obtained under standard conditions to obtain a frequency coefficient. "Standard conditions" refers to the conditions described in Chinese patent CN119086221B.

[0040] Step 5) Repeat steps 1) to 4) for each soil type, each soil moisture range, and each soil temperature range three times, take the average value, and obtain the final frequency value coefficient.

[0041] Step 6) List the relationship between soil quality, soil temperature, soil moisture content, and final frequency value coefficients, as shown in Table 1.

[0042] Table 1 is the relationship table of soil quality, soil temperature, soil moisture content and frequency value coefficient based on physical separation method:

[0043] .

[0044] The present invention also provides a method for rapid in-situ measurement of soil exchangeable nutrients, which uses the device for rapid in-situ measurement of soil exchangeable nutrients of the present invention, and comprises the following steps:

[0045] Step 1: Install the outer tube of the multi-frequency sensor into the soil in situ. Install the soil temperature sensor into the soil so that the installation depth of the soil temperature sensor is the same as the installation depth of the outer tube of the multi-frequency sensor. Connect the multi-frequency sensor and soil temperature sensor to the wireless terminal DTU and solar power supply device.

[0046] Specifically, in step 1, the outer tube of the multi-frequency sensor is processed by the vertical ring knife method, and the outer tube of the multi-frequency sensor can be installed in situ at a soil depth of 40 cm. The installation range of the soil temperature sensor is within a radius of 40-50 cm with the outer tube of the multi-frequency sensor as the center.

[0047] Step 2: During the test, insert the test end of the multi-frequency sensor into the outer tube to collect the frequency value of the soil. The frequency value of the soil and the soil temperature data measured by the soil temperature sensor are uploaded to the cloud.

[0048] Step 3: The cloud calculates the exchangeable nutrient index of the soil based on the soil frequency value and soil temperature data, the frequency coefficient database, and the calculation model. The method for determining soil volumetric water content is known in the art and will not be further described here.

[0049] Step 4: The terminal obtains the soil exchangeable nutrient indicators to be measured from the cloud by accessing and displaying them.

[0050] Example 1

[0051] In a loamy soil area with corn as the crop, the outer tube of a multi-frequency sensor was installed in situ in the soil. Specifically, the outer tube was installed using a vertical ring knife technique at a depth of 40 cm. This enabled in-situ data collection at depths of 10 cm, 20 cm, 30 cm, and 40 cm. After the outer tube was installed, the multi-frequency sensor was placed inside. Next, a soil temperature sensor was installed, with the outer tube of the multi-frequency sensor as the center and a radius of 43 cm. The installation depth was the same as the outer tube installation depth, 40 cm. The multi-frequency sensor and soil temperature sensor were connected to a wireless terminal (DTU) and a solar power supply.

[0052] During testing, the test end of the multi-frequency sensor is inserted into the outer tube to collect soil frequency values. These values, along with the soil temperature data measured by the soil temperature sensor, are then uploaded to the cloud via the wireless terminal (DTU). Specifically, the in-situ rapid soil nutrient measurement device can be set to automatically collect and upload data to the cloud once a day. The cloud calculates the soil exchangeable nutrient indicators based on the soil frequency and temperature data, a frequency coefficient database, and a calculation model. The terminal accesses the soil exchangeable nutrient indicators from the cloud and displays them.

[0053] In this embodiment, the exchangeable ammonium nitrogen content and exchangeable nitrate nitrogen content indicators at a soil depth of 20 cm are obtained as an example. Based on the calculation model and the frequency value coefficient database, the cloud side calculates that at a soil depth of 20 cm, the soil temperature is 21°C, the volumetric water content is 24%, the exchangeable ammonium nitrogen content is 1.15 mg / kg, and the exchangeable nitrate nitrogen content is 9.45 mg / kg.

[0054] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limiting the present invention. Any changes, modifications, substitutions and variations of the above embodiments by a person skilled in the art fall within the scope of the present invention.

Claims

1. A soil exchangeable nutrient in-situ rapid measurement device, characterized by: It includes a multi-frequency sensor, a soil temperature sensor, and a cloud. The multi-frequency sensor and soil temperature sensor transmit data to the cloud through a wireless terminal DTU. It also includes a terminal, which is connected to the cloud through access. The multi-frequency sensor and soil temperature sensor are also connected to a power supply device. The cloud has the following calculation model: ； ； Among them, FSIC is the frequency scale index characteristic of dielectric function; i is the soil exchangeable nutrient marker, f 土壤 is the frequency value of the soil, f 纯水 is the frequency value of pure water, f 干土 is the frequency value when the soil moisture content is 0%, f 空气 is the frequency value of air, n is the frequency value coefficient; -kv is the sensitive frequency point parameter of the soil test index under multiple spectra; Cxi is the soil exchangeable nutrient test index, including exchangeable nitrate nitrogen content, exchangeable ammonium nitrogen content, adsorbed phosphorus content, exchangeable potassium content, organic matter content, and cation exchange capacity; the cloud has a frequency value coefficient database, which includes soil type, soil temperature, soil moisture content, and frequency value coefficient; the soil types in the database include sandy soil, loamy soil, and clay soil; the soil temperature range of the database is 0~50℃, and is divided into sections every 5℃; the soil moisture content range of the database is 0% to saturation, and is divided into sections every 5% volume moisture content; the frequency value coefficient n of the database is obtained by using a physical separation method to test the soil frequency data within the corresponding soil type, soil temperature, and soil moisture content range, and then obtaining the ratio of the test soil frequency data to the soil frequency data under the standard state. After repeating several times and taking the average value, the frequency value coefficient n is obtained.

2. The in-situ rapid measurement device for soil exchangeable nutrients according to claim 1, characterized in that: The soil moisture content in the database ranges from 0% to saturation. The soil moisture content ranges from 0% to 30% for sandy soil, 0% to 45% for loamy soil, and 0% to 50% for clay soil.

3. A method for rapid in-situ measurement of soil exchangeable nutrients using the device according to any one of claims 1 to 2, characterized in that: The steps include: Step 1: Install the outer tube of the multi-frequency sensor into the soil in situ. Install the soil temperature sensor into the soil to the same installation depth as the outer tube of the multi-frequency sensor. Connect the multi-frequency sensor and soil temperature sensor to the wireless terminal DTU and solar power supply device. Step 2: During the test, the test end of the multi-frequency sensor is inserted into the outer tube to collect the frequency value of the soil. The frequency value of the soil and the soil temperature data measured by the soil temperature sensor are uploaded to the cloud through the wireless terminal DTU; Step 3: The cloud obtains the soil exchangeable nutrient index to be measured based on the soil frequency value and soil temperature data, the frequency value coefficient database and the calculation model; Step 4: The terminal obtains the soil exchangeable nutrient indicators to be measured from the cloud by accessing and displaying them.

4. The method for rapid in-situ measurement of soil exchangeable nutrients according to claim 3, wherein: In step 1, the outer tube of the multi-frequency sensor is processed by a vertical ring knife method.

5. The method for rapid in-situ measurement of soil exchangeable nutrients according to claim 3, wherein: The installation range of the soil temperature sensor is within a radius of 40-50cm with the outer tube of the multi-frequency sensor as the center.

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