Soil matrix evaluation and identification method

Abstract

The invention relates to the technical field of soil matrix identification, and particularly discloses a method for evaluating and identifying a soil matrix, which comprises the following steps: selecting a soil matrix to be identified, dehydrating and rehydrating, and then changing the variation trend of soil root interface water potential, plant xylem water potential and leaf transpiration; according to the method, the soil quality is reasonably analyzed by measuring the change trend of the soil root interface water potential, the plant xylem water potential and the leaf transpiration, so that it is guaranteed that the identification result is high in accuracy, and the evaluation method is comprehensive.

Description

Technical Field

[0001] The invention belongs to the technical field of soil matrix identification, and particularly relates to a method for soil matrix evaluation and identification. Background Art

[0002] Heightened concern about runoff pollution from nursery operations has fueled research into improved irrigation control systems. One approach under investigation is subsurface irrigation, where the potting medium draws water from a capillary mat placed beneath the pot. In this system, the hydraulic properties of the medium are crucial. The medium must not only retain and deliver water to the roots but also absorb water from the mat to the roots in sufficient quantities to prevent growth-reducing water stress. Therefore, selecting the right growing soil medium is crucial for the proper use of this irrigation system.

[0003] Traditional evaluation of growth soil media often relies on static properties such as total porosity and indicators derived from water release curves, which leads to limited soil matrix assessment methods, poor accuracy and incompleteness. Summary of the Invention

[0004] The object of the present invention is to provide a method for soil matrix evaluation and identification to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for soil matrix evaluation and identification comprises the following steps:

[0007] Select the soil substrate that needs to be identified, place it in a flowerpot, and plant cherry plum seedlings in the flowerpot. Maintain the sunshine time at 10 hours, the temperature at 15℃-24℃, and water regularly to keep the soil surface moist.

[0008] Cultivate the plants for two weeks to allow them to adapt to the new environment, and dehydrate and rehydrate the plants one month after planting;

[0009] When dehydrating, reduce the amount of watering and measure the soil water potential with a ten-digit meter to maintain the minimum soil water potential at -50kPa;

[0010] During rewatering, the amount of water was gradually increased, and leaf transpiration was first measured using a portable gas exchange system as the water potential changed;

[0011] Then, the xylem water potential was measured using the pressure chamber method and the data were recorded;

[0012] Draw a line graph of soil root surface water potential-xylem water potential and a line graph of soil root surface water potential-xylem transpiration rate for data analysis.

[0013] Preferably, the soil water potential is monitored using a tensiometer, wherein a tensiometer of the tensiometer is inserted into the potting soil mixture with a ceramic sensor head placed in the center of the soil volume for measurement.

[0014] Preferably, the xylem water potential is measured between 11:00 and 15:00 using a pressure chamber method to measure the xylem water potential of three branches at the top, middle and lower positions of the crown. A branch with a diameter of 6 mm is cut off 20 cm from the top, with leaves attached, and immediately placed in a polyethylene bag and then placed in a pressure chamber. The air humidity in the pressure chamber is maintained at a saturated state to prevent circulating water loss. The pressure application speed is faster at the beginning of the measurement and then slowed to 0.01 MPa·s when the pressure approaches the xylem water potential of the plant. -1 , when water seeps out of the xylem and saturates the cut end of the petiole, stop applying pressure.

[0015] Preferably, the transpiration rate is determined in a greenhouse using a portable gas exchange system, measuring individual leaves from the upper, middle and lower parts of the canopy.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention rationally analyzes the quality of soil by measuring the changing trends of the water potential at the soil-root interface, the water potential at the plant's xylem, and the transpiration of leaves, thereby ensuring that the identification results are highly accurate and the evaluation method is more comprehensive. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A soil root surface water potential-xylem water potential diagram for implementing the present invention;

[0019] Figure 2 This is a soil root surface water potential-xylem water potential diagram in the second embodiment of the present invention;

[0020] Figure 3 The soil root surface water potential-xylem water potential diagram for the third embodiment of the present invention;

[0021] Figure 4 A soil root surface water potential-transpiration rate diagram for an embodiment of the present invention;

[0022] Figure 5 This is a soil root surface water potential-transpiration rate diagram in the second embodiment of the present invention;

[0023] Figure 6 This is a soil root surface water potential-transpiration rate diagram for the third embodiment of the present invention; DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example 1:

[0026] See also Figures 1 to 6 As shown, a method for soil matrix evaluation and identification:

[0027] The flower pots are made of PP resin, which is environmentally friendly, odorless, sun-proof, drop-resistant, durable, well-drained and breathable, and has strong root control. Each flower pot has a volume of 6L, a pot diameter of 22cm, a bottom diameter of 17.5cm, a tray diameter of 20cm, a pot height of 19.5cm, and a soil depth of 15.6cm. The total soil weight is approximately 8kg.

[0028] Mixed substrate 1 was made of 4.2 kg (52%) of brown peat moss, 2.6 kg (33%) of bark, 400 g (5%) of compost (leaves and grass), and 800 g (10%) of coarse beach sand;

[0029] Plant cherry plum seedlings with 10 hours of sunshine and a temperature between 15°C and 24°C, and water the soil regularly to keep the surface moist. Cultivate the plants for two weeks to allow them to adapt to the new environment, and dehydrate and rehydrate the plants one month after planting. Reduce the amount of water during dehydration and measure the soil water potential with a ten-digit meter to maintain the minimum soil water potential at -50kPa. Gradually increase the amount of water during rehydration, and as the water potential changes, first measure leaf transpiration using a portable gas exchange system. Then use the pressure chamber method to measure the xylem water potential and record the data. Draw a line graph of soil root surface water potential-xylem water potential and a line graph of soil root surface water potential-xylem transpiration rate for data analysis.

[0030] Example 2:

[0031] A method for soil matrix assessment and identification:

[0032] The flower pots are made of PP resin, which is environmentally friendly, odorless, sun-proof, drop-resistant, durable, well-drained and breathable, and has strong root control. Each flower pot has a volume of 6L, a pot diameter of 22cm, a bottom diameter of 17.5cm, a tray diameter of 20cm, a pot height of 19.5cm, and a soil depth of 15.6cm. The total soil weight is approximately 8kg.

[0033] Mixed substrate 2 was made of 2.4 kg (30%) of brown peat moss, 4.8 kg (60%) of bark compost, and 800 g (10%) of coarse beach sand;

[0034] Planting cherry plum seedlings, maintaining the sunshine time at 10 hours, the temperature at 15℃-24℃, and watering regularly to keep the soil surface moist; cultivating for two weeks to allow the plants to adapt to the new environment, and dehydrating and rehydrating the planted plants one month after planting; reducing the amount of watering during dehydration and measuring the soil water potential with a ten-digit meter to maintain the minimum soil water potential at -50kPa; gradually increasing the amount of watering during rehydration, and first measuring the leaf transpiration through a portable gas exchange system as the water potential changes; then using the pressure chamber method to measure the xylem water potential and record the data; drawing a line graph of soil root surface water potential-xylem water potential and a line graph of soil root surface water potential-xylem transpiration rate, and performing data analysis,

[0035] Example 3:

[0036] A method for soil matrix assessment and identification:

[0037] The flower pots are made of PP resin, which is environmentally friendly, odorless, sun-proof, drop-resistant, durable, well-drained and breathable, and has strong root control. Each flower pot has a volume of 6L, a pot diameter of 22cm, a bottom diameter of 17.5cm, a tray diameter of 20cm, a pot height of 19.5cm, and a soil depth of 15.6cm. The total soil weight is approximately 8kg.

[0038] Mixed substrate 3 was made of 4 kg (50%) of brown peat moss, 3.2 kg (40%) of fresh coniferous sawdust, and 800 g (10%) of coarse beach sand;

[0039] Plant cherry plum seedlings with 10 hours of sunshine and a temperature between 15°C and 24°C, and water the soil regularly to keep the surface moist. Cultivate the plants for two weeks to allow them to adapt to the new environment, and dehydrate and rehydrate the plants one month after planting. Reduce the amount of water during dehydration and measure the soil water potential with a ten-digit meter to maintain the minimum soil water potential at -50kPa. Gradually increase the amount of water during rehydration, and as the water potential changes, first measure leaf transpiration using a portable gas exchange system. Then use the pressure chamber method to measure the xylem water potential and record the data. Draw a line graph of soil root surface water potential-xylem water potential and a line graph of soil root surface water potential-xylem transpiration rate for data analysis.

[0040] Among them, brown peat moss is taken from the Northeast region. Peat moss can maintain the humidity of the surrounding environment in the soil. Peat moss grows in humid places, such as swamps, wetlands, etc. It has a very tenacious growth ability. Peat moss has a sponge structure and can absorb about seven times its own weight in water.

[0041] Pine bark is an excellent soil amendment material. Even after being crushed, it remains soft and fluffy even after water is added. Pine bark has "water-absorbing" areas that absorb large amounts of water and nutrients. Furthermore, pine bark contains numerous tiny pores that store water and nutrients. When mixed with soil, pine bark significantly increases the soil's water and fertilizer storage capacity. It also improves soil air permeability and water retention. Because pine bark has a neutral pH, it does not adversely affect soil pH. Furthermore, pine bark is rich in organic matter, and after fermentation, it contributes to the soil's organic matter and humus.

[0042] Coarse beach sand is made of coarse river sand. Plants like a loose growth environment. Only in a loose and breathable environment can the roots of plants grow stronger and more vigorous. To meet this requirement, a certain amount of sand can be added to the soil. Sand has no stickiness and is very breathable. When mixed in the soil, it makes the original soil looser. After watering, it is no longer hard and the soil will no longer become compacted.

[0043] Compost (leaves and grass) is made up of fallen maple leaves and weeds in moist soil. The fallen maple leaves are high in protein, nitrogen, potassium, magnesium and iron, which help plant growth.

[0044] Bark compost is pine bark fermented with other organic materials into compost, which is then mixed into the soil as a base fertilizer. During the fermentation process, the pine bark mixes with organic materials such as vegetable leaves, pine needles, dead leaves, bean cake, chicken manure, sheep manure, cow manure, and pig manure. After a period of decomposition, it produces a rich organic fertilizer. Mixing this fermented compost into the soil can significantly improve soil texture and increase soil fertility. It also adds a large amount of organic matter, humus, and beneficial bacteria to the soil, providing long-lasting nutrition for plant growth.

[0045] Fresh sawdust from coniferous trees is an organic fertilizer rich in organic matter, nitrogen, phosphorus, potassium and other nutrients. Among them, organic matter can serve as a source of organic carbon for the soil, which can improve the soil's fertility and water retention capacity. Elements such as nitrogen, phosphorus, and potassium are the main nutrients necessary for plant growth and can promote plant growth and development. Fresh sawdust from coniferous trees can increase the soil's ability to retain water and fertilizer. On the one hand, the organic matter in the sawdust can absorb and retain water, increasing the soil's water retention capacity. On the other hand, the nutrients in the sawdust can be slowly released, providing plants with a continuous supply of nutrients and improving soil fertility. Fresh sawdust from coniferous trees can improve soil structure. Since sawdust particles are relatively coarse, applying sawdust can reduce soil compaction and promote soil weathering and aggregate decomposition. At the same time, the application of sawdust can increase soil permeability and drainage, improve soil ventilation, and benefit plant growth.

[0046] Experimental determination:

[0047] 1. Initial particle size distribution of different soil samples during production

[0048]

[0049] 2. Determination of soil and xylem water potential

[0050] The three soil matrix mixtures in Examples 1 to 3 were mixed and evenly placed in flower pots of the specifications described above. Cherry plum seedlings (Tai'an, Shandong) were planted in the flower pots. The three transplanted plants were placed under the same culture conditions during the experiment, with the sunshine time maintained at 10 hours and the temperature maintained at 15°C-24°C. Watering was carried out regularly to keep the soil surface moist. The plants were cultivated for two weeks to adapt to the new environment. One month after planting, the three pots of plants were first dehydrated and then rehydrated. During dehydration, the amount of watering was reduced and the soil water potential was measured with a ten-digit meter. The minimum soil water potential was maintained at -50 kPa. During rehydration, the amount of watering was gradually increased. As the water potential changed, the leaf transpiration was first measured by a portable gas exchange system and then the xylem water potential was measured using a pressure chamber method. The data were recorded, and a soil root surface water potential-xylem water potential line graph and a soil root surface water potential-xylem transpiration rate line graph were drawn for data analysis.

[0051] The reason for measuring leaf transpiration rate before xylem water potential is that for most of the day, water in the plant's xylem water chain is constantly under tension due to transpiration. If the leaves are covered to prevent transpiration, the water level will approach equilibrium after a short period of time, meaning that the xylem water potential approaches or equals the leaf cell water potential.

[0052] When the leaves are cut off, the tension in the xylem is released and the sap in the vessels retracts into the xylem (the lower the water potential, the more it retracts).

[0053] Place the cut leaf in a pressure chamber and apply pressure to push the xylem sap back to the incision. The pressure at this time is equal to the value of the xylem tension before the leaf was cut. In other words, the pressure (equilibrium pressure) is roughly equal to the water potential value of the leaf.

[0054] Soil water potential refers to the potential energy possessed by soil water, that is, the work required to move a very small amount of water from a pure water pool at a specific height to the soil water reversibly and isothermally under atmospheric pressure.

[0055] Xylem water potential refers to the pressure or tension of water molecules in the xylem of a plant and is an important parameter for plant water absorption and transport.

[0056] Soil water potential was monitored using a tensiometer (TEROS 31 laboratory soil water potential sensor, Beijing Ligaotai Technology Co., Ltd., China) by inserting a tensiometer of the tensiometer with a ceramic sensor head (50 mm long and 18 mm in diameter) into the potting soil mixture and placing it in the center of the soil volume for measurement.

[0057] Xylem water potential was measured between 11:00 and 15:00 using a pressure chamber method on three branches at the top, middle, and lower locations of the canopy. Branches with a diameter of 6 mm were cut 20 cm from the topmost point, with leaves attached, immediately placed in a polyethylene bag, and then placed in a pressure chamber (Model 3000, Soil Moisture Equipment, Inc., Santa Barbara, CA 93105, USA). The air humidity in the pressure chamber was maintained at saturated levels to prevent circulating water loss. The pressure application rate was rapid at the beginning of the measurement and then slowed to 0.01 MPa·s⁻¹ as the pressure approached the plant's xylem water potential. When water seeped out of the xylem and saturated the cut end of the petiole, pressure was stopped, and half of the 14 branches were cut back so that branch removal would not result in noticeable leaf loss.

[0058] 3. Measurement of transpiration

[0059] Transpiration rates were measured in a greenhouse using a portable gas exchange system (L1-1600, Licor, Lincoln, Nebraska, USA). Five individual leaves from the upper, middle, and lower canopy were measured, with a leaf area of ​​2 cm2 contained in a leaf chamber. The light intensity, expressed as photosynthetic photon flux, was 700 ± 100 μmol·m-2·s-1. The air humidity in the leaf chamber was set to a level similar to the greenhouse ambient humidity. After the measurement, all leaves of the plant were removed, and the total leaf area was measured using a leaf area meter (LI-3000A, Zhongheng Rixin (Tianjin) Technology Co., Ltd.).

[0060] Soil root surface water potential - xylem water potential:

[0061] Response of xylem water potential to changes in soil matrix water potential under different soil matrices

[0062] Graphpad Prism was used to calculate the area between the two broken lines showing the change of xylem water potential with mixed soil matrix 1 and the X-axis below. The area between the dehydration broken line and the X-axis was 80.77, the area between the rehydration broken line and the X-axis was 58.12, and the area difference between the two broken lines of dehydration and rehydration was 22.65, which was recorded as S 1-1

[0063] Graphpad Prism was used to calculate the area between the two broken lines showing the change of xylem water potential with mixed soil matrix 2 and the X-axis below. The area between the dehydration broken line and the X-axis was 112.0, the area between the rehydration broken line and the X-axis was 66.30, and the area difference between the two broken lines of dehydration and rehydration was 45.70, which was recorded as S 1-2 .

[0064] Graphpad Prism was used to calculate the area between the two broken lines showing the change of xylem water potential with mixed soil matrix 3 and the X-axis below. The area between the dehydration broken line and the X-axis was 108.10, the area between the rehydration broken line and the X-axis was 99.21, and the area difference between the two broken lines of dehydration and rehydration was 8.89, which was recorded as S 1-3 .

[0065] Conclusion: After data processing and analysis, we get S 1-3 The area of ​​​​the mixed soil matrix is ​​the smallest, indicating that the water potential of the plant xylem can basically be restored to the level before dehydration after dehydration and rehydration. It can be concluded that the quality of the mixed soil matrix 3 is better.

[0066] Soil root surface water potential-transpiration rate

[0067] Response of transpiration rate to changes in soil water potential under different soil matrices:

[0068] Graphpad Prism was used to calculate the area between the two broken lines showing the change of transpiration rate with mixed soil matrix 1 and the X-axis below. The area between the dehydration broken line and the X-axis was 50.80, and the area between the rehydration broken line and the X-axis was 101.60. The area difference between the two broken lines of dehydration and rehydration was 50.80, which was recorded as S 2-1 .

[0069] Graphpad Prism was used to calculate the area between the two broken lines showing the change of transpiration rate with mixed soil matrix 1 and the X-axis below. The area between the dehydration broken line and the X-axis was 60.85, the area between the rehydration broken line and the X-axis was 138.2, and the area difference between the two broken lines of dehydration and rehydration was 77.35, which was recorded as S 2-2 .

[0070] Graphpad Prism was used to calculate the area between the two broken lines showing the change of transpiration rate with mixed soil matrix 1 and the X-axis below. The area between the dehydration broken line and the X-axis was 200.5, the area between the rehydration broken line and the X-axis was 233.6, and the area difference between the two broken lines of dehydration and rehydration was 33.1, which was recorded as S 2-3 .

[0071] Conclusion: After data processing and analysis, we get S 2-3The area is the smallest, indicating that the plant transpiration rate can basically return to the level before dehydration after the soil matrix is ​​dehydrated and rehydrated. It can be concluded that the quality of mixed soil matrix 3 is better.

[0072] Combine Figures 1 to 6 Comprehensive analysis of the two sets of line graphs shows that the quality of mixed soil matrix 3 is better.

[0073] As can be seen from the above, the present invention uses dynamic monitoring of the correlation changes of the soil-root interface water potential, xylem water potential and leaf transpiration of cherry-plum plants with dehydration and rehydration to draw a line graph and analyze the quality of the soil matrix through comprehensive results.

[0074] The changes in plant xylem water potential and leaf transpiration along with the water potential at the soil-root interface can vividly reflect the growth status of the plant in that soil matrix, thereby demonstrating the quality of the soil matrix. Soil xylem water potential and transpiration are susceptible to changes in external conditions, facilitating precise measurement and improving the accuracy of the method. Dehydration and rehydration of different soil matrices facilitate observation of changes in plant physiological indicators, followed by multi-dimensional comparison in the horizontal and vertical directions to improve the accuracy of soil matrix assessment and identification.

[0075] In summary, this method of judging soil medium quality by dynamically measuring soil root interface water potential, xylem water potential, and leaf transpiration rate, combined with mathematical fitting curve calculation, can more accurately evaluate soil matrix.

[0076] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for soil matrix evaluation and identification, characterized in that: The following steps are involved: Select the soil substrate that needs to be identified, place it in a flowerpot, and plant cherry plum seedlings in the flowerpot. Maintain the sunshine time at 10 hours, the temperature at 15℃-24℃, and water regularly to keep the soil surface moist; Cultivate for two weeks to allow the plants to acclimate to the new environment, and dehydrate and rehydrate the planted plants one month after cultivation; When dehydrating, reduce the amount of watering and measure the soil water potential with a ten-digit meter to maintain the minimum soil water potential at -50 kPa; When rewatering, gradually increase the amount of water, and first measure leaf transpiration using a portable gas exchange system as the water potential changes; Then use the pressure chamber method to measure the xylem water potential and record the data; Draw a line graph of soil root surface water potential-xylem water potential and a line graph of soil root surface water potential-xylem transpiration rate for data analysis.

2. A soil matrix evaluation and identification method according to claim 1, characterized in that: The soil water potential was monitored using a tensiometer, where a tensiometer was inserted into the potting soil mix with a ceramic sensor head placed in the center of the soil volume.

3. A soil matrix evaluation and identification method according to claim 1, characterized in that: The xylem water potential was measured using the pressure chamber method at the top, middle and lower positions of the crown between 11:00 and 15:

00. Branches with a diameter of 6 mm were cut off at 20 cm from the top, with leaves attached, and immediately placed in a polyethylene bag and then placed in a pressure chamber. The air humidity in the pressure chamber was kept at saturated state to prevent circulating water loss. The pressure application speed was faster at the beginning of the measurement and then slowed down to 0.01 Mpa·s when the pressure approached the xylem water potential of the plant. -1 , when water seeps out of the xylem and saturates the cut end of the petiole, stop applying pressure.

4. A soil matrix evaluation and identification method according to claim 1, characterized in that: The transpiration rate was determined in a greenhouse using a portable gas exchange system, measuring individual leaves from the upper, middle and lower canopy.

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