EP3902387A1

EP3902387A1 - Device and method for detecting a fertilisation status

Info

Publication number: EP3902387A1
Application number: EP20746544.4A
Authority: EP
Inventors: Daniel Weber; Thomas Berberich
Original assignee: Phytoprove Pflanzenanalytik Ug Haftungsbeschraenkt
Current assignee: Phytoprove Pflanzenanalytik Ug Haftungsbeschraenkt
Priority date: 2019-06-17
Filing date: 2020-06-17
Publication date: 2021-11-03
Also published as: WO2020253915A1

Abstract

The invention relates to a device for detecting the fertilisation status in plants, said device containing at least one light source (2), a receiver (3), a time recorder (4), and an evaluation unit (5). In the method according to the invention using said device (1), the light source (2) sends a light signal for a first predefined period Δt1. After the first predefined period Δt₁, the receiver (3) receives a signal for a second predefined period Δt₂ and acquires this time-dependently. In this second predefined period Δt₂, a quotient between the minimum and maximum signal is determined or an extreme value of the signal is compared with at least one threshold value. A signal regarding the fertilisation status is output according to the result.

Description

Device and method for recognizing the fertilizer status

The present invention relates to an apparatus and a method for recognizing the fertilization status in plants.

Due to their sessile way of life, plants cannot escape environmental influences and are therefore damaged under certain conditions. This leads to considerable losses, which can only be compensated through great effort. If damage is already visible to the human eye, it is usually too late to initiate countermeasures. An early diagnosis of exposure to nutrient or water deficiency, heat or cold allows early, targeted countermeasures. Yield and quality of crops are dependent on the sufficient

Supply of nutrients that is usually only achieved by adding fertilizer.

In order to feed the growing world population, in the

Past an intensification of production in agriculture with increased use of fertilizers took place. This releases reactive nitrogen compounds into the environment (air, groundwater).

The Federal Environment Agency therefore recommends reducing the

Nitrogen surplus to 50 kg per hectare / year. It is therefore imperative to adapt the use and dosage of fertilizers as precisely as possible to the needs of the plants. The measurement of the fertilization status of the plants is a prerequisite for this. The targeted fertilization of cultivated areas is not only desirable in professional agriculture. In the urban environment, more and more areas are being used, on the one hand, to improve the urban microclimate and to adapt the cities to climate change, for example through green roofs and facades adapt. On the other hand, crops are cultivated in a decentralized manner in order to supply the local population with vegetables and fruit. In all cases, targeted fertilization is necessary to achieve high quality and production.

The fertilization status of plants can be easiest via the

Observation of visible changes such as leaf color or

Determine growth size. If a deficit can be identified, the time for effective countermeasures has already passed. This also applies to large-scale remote observation via drone or satellite. Even the laborious determination of the nitrogen content of the soil does not provide any information about the actual fertilization status of the plant. In accordance with the state of the art, invisible changes can be determined by analyzes in the laboratory. These methods are complex and require parts of the plant to be removed.

Methods are known from the prior art, which the

Use the property of leaves to absorb blue, green and / or red light components. While light with wavelengths smaller than 700 nm is predominantly absorbed, longer wavy light is absorbed by a

Wavelength greater than 800 nm predominantly reflected. The cell structure and the water content of the leaves lead to the absorption in the

beginning infrared range at a turning point (Red Edge Inflection Point, REIP) merges into reflection. This REIP is used to determine the nitrogen content.

As chlorophyll fluorescence, a phenomenon of light absorption of

Called chlorophyll (leaf green). During the photochemical conversion of photons (light quanta) into chemical energy it comes to

Loss of performance. In addition to the desired transfer of electrons to the electron transport chain, some of the electrons are supplied via light Energy converted into heat, phosphorescence and fluorescence. The chlorophyll fluorescence is used to measure photosynthetic activity non-destructively. The fluorescence is triggered by the emission of light energy by excited chlorophyll a molecules and follows the excitation of these molecules by irradiated light.

[0007] WO 2011/15598 A1 discloses a measuring device for determining the vegetation index value (REIP) of plants. The measuring device has a plurality of light-transmitting elements in the form of LEDs, each of which is essentially monochrome light of a predetermined

Emits wavelength, on. A light-receiving element in the form of a light-frequency converter receives light from the light-transmitting elements reflected by the plants and generates a signal indicating the respective intensity of the light received. This becomes the

Vegetation index value REIP calculated to determine the chlorophyll and nitrogen content of plants.

In the method described in DE 102010034603 B4, a plant is irradiated with red and green light and the reflected light is detected by means of two receivers. This becomes a

Reflection coefficient determined for red and green light. A parameter can be determined from the two reflection coefficients, which is characteristic of whether a healthy leaf with normal one

Chlorophyll content is present or not.

DE 102011050877 B4 discloses a device and a method for determining the fertilizer requirement, in which characteristic curves or tables must first be created, with the aid of which a measurement signal is evaluated. [0010] All known methods are so complex that the devices required are comparatively expensive.

It would be desirable to offer a device and a method that is inexpensive even to laypeople without specialist knowledge and

Calibration attempts make it possible to obtain information on the fertilization status of plants.

[0012] The present invention was therefore based on the object of a

To create a device and a method which provides information on the fertilization status of any plants easily and quickly.

According to the invention, this object is achieved on the one hand by a device according to patent claim 1. Thus, a device for recognizing the fertilization status of plants not only has at least one light source, a receiver and an evaluation unit, but also a time recording and a data memory.

[0014] An encapsulation can optionally be arranged around the transmitter and receiver. If the device with the encapsulation is placed on a sheet and the method is carried out, then during the measurement

Avoid exposure to light from outside. Xw

Another aspect of the invention relates to a method for recognizing the fertilization status in plants.

In the method according to the invention for detecting the fertilization status in plants with a device which contains at least one light source, a receiver, a time recording and an evaluation unit, the light source initially sends a light signal for a first predetermined period of time Ati. After the first predetermined time period Ati, the receiver receives and records a signal as a function of time for a second predetermined time period At2. In this second predetermined time period At2 a quotient between the minimum and maximum signal is determined or an extreme value of the signal with at least one

Threshold value compared. According to the result of this

Arithmetic operation, a signal on the fertilization status is output.

Preferred embodiments of the invention can be found in the subclaims and the detailed description below.

So the light source can preferably light with a wavelength of

between 780 and 880 nm, in particular from 800 to 860 nm,

preferably send 820 nm.

The receiver is designed and set up to receive light with a wavelength of 780 and 880 nm, in particular from 800 to 860 nm, preferably 820 nm, which is reflected from the sheet or sheets and / or other surfaces in question.

While measuring methods in the prior art on the principle of

Build transmission, i.e. how much light arrives on the opposite side of the leaf is based on the present one

Method preferably based on the detection of reflected light which is detected by the receiver.

In this wavelength range is the absorption range of cations of P700 chlorophyll, with a peak at 820 nm (P700 is that

Photosystem I reaction center).

The optimal point in time for a measurement varies and is between 0.7

Milliseconds and 100 milliseconds, preferably between 8 milliseconds and 40 milliseconds, in particular between 8 milliseconds and 20 milliseconds. The minimum in this range is taken as the measured value for the nitrogen status. The time to measure the nitrogen status as a marker for the

The fertilizer status should preferably be in the "fast phase" of the kinetics (700 microseconds to 20 milliseconds)

Nitrogen status is taken to the minimum in this area.

It is preferred either that the period At2 begins directly after the end of the period Ati, or that the period begins in parallel with the period AL.

Another advantage of the present method is that the

Plants do not need to be darkened before measurement. According to the prior art, it is often necessary that a darkening has to take place for a period of about 20 minutes before measurements can be taken.

According to the device according to the invention and the method according to the invention, this is not necessary.

Furthermore, it can be preferred according to the invention that a further light source is included as a photosynthesis light source which is designed and set up to send light with a wavelength of 500 and 1000 nm, in particular from 550 to 800 nm, preferably 630 nm , wherein the photosynthesis light source, in particular partially or completely, is operated parallel to the light source.

A photosynthetic light switched in parallel to the measuring light excites the

Photosynthesis. This results in the biophysical effect, namely the excitation of photosystems II and I, with one

Electron transport from PS II via a transport chain to PS I up to the provision of energy for carbon fixation. The photosynthesis taking place then changes the redox status of the P700 chlorophyll, which according to the invention is detected at 820 nm. [0029] The wavelength of the photosynthetic light can also be in a different wavelength range than that specified above, for example in the blue wavelength range, or also full spectrum white light.

The device can with a computer, smartphone, tablet or

connected to another device, with the connection

preferably done wirelessly.

[0031] The device can optionally be used to control a fertilizer device

be used.

The device according to the invention and the

Method according to the invention explained in detail with reference to the figures.

Show:

Figure 1 shows an inventive device for recognizing the

Fertilizer status in plants and

Figure 2 shows a signal evaluation when performing the

method according to the invention.

Figure 1 shows a device 1 for detecting the fertilization status in plants with a light source 2, a receiver 3 and a

Evaluation unit 5. The evaluation unit 5 is connected to a time recording 4, a transmitter 11 and a data memory 6.

The light source 2 can be an infrared LED, which preferably emits at a wavelength of 820 nm. The receiver 3 can be a photodiode which preferably receives light with a wavelength of approximately 820 nm. It is obvious to the person skilled in the art that other wavelengths as in the preferred embodiments described above can also be advantageous.

A sheet 8 to be examined is located below the device.

A light beam 9 radiates from the light source 2 as a pulse to the sheet 8. The sheet 8 absorbs the energy of the light beam 9, whereby

Double bonds in the molecules are changed. After

When irradiated, these double bonds return to their original position, which means that part of this energy is reflected in a fluorescent manner.

The reflection is somewhat delayed due to the processes in sheet 8, initially increases, reaches a maximum of intensity and then decreases again. The reflection takes place in all directions, with a reflection beam 10 reaching the receiver 3. A signal is sent from the receiver 3

Evaluation unit 5. The signal is recorded over time with the aid of time recording 4 and data memory 6 and is stored. After the time-limited signal detection, the evaluation unit 5 evaluates the signals detected in practice, recognizes the fertilization status of the leaf 8 and outputs a corresponding signal. The signal output can optionally take place directly on the device 1 via a display or signal lights. Furthermore, the signal from the internal transmitter 11 can for example via Bluetooth to a smartphone 7 or another external

Evaluation device are output.

Figure 2 shows the time course of the energy input and the

Reflection on the method according to the invention. At the beginning of the method, a light signal E is sent to a sheet to be examined at time 0 for a period Ati. The leaf absorbs the energy, causing some of the double bonds to shift. When jumping back into a lower-energy state, energy is released again in the form of fluorescent reflection. Surprisingly, this shows the following effect:

A few nanoseconds after irradiation, the fluorescent continues

Reflection, which first rises to a maximum and then falls back to zero. Line A shows the signal of a healthy, adequately fertilized leaf; the maximum of the reflection is MA. In the case of a weakly nutrient-supplied leaf (line B), the signal of the fluorescent reflection is lower overall. The maximum MB for a poorly nutrient-supplied leaf is lower than the maximum MA for a healthy, sufficiently fertilized leaf. In addition, it can be determined that the measurement curve drops earlier again, so that the minimum MB is reached earlier than the maximum MA. In the case of a leaf with an acute nutritional deficiency (line C), the signal of the fluorescent reflection is again lower. The maximum Mc for a leaf with an acute nutrient deficiency is lower than the maximum MB for a leaf that is poorly supplied with nutrients. The maximum M _c is reached earlier than the maximum MB.

A criterion can be derived from this. The maximum remains one

Measurement curve below a lower limit value U, so is more acute

Nutrient deficiency. After the evaluation unit 5 has determined such a state, a corresponding signal is output; fertilization can be initiated with it. If the maximum of a measurement curve exceeds an upper limit value O, the leaf is sufficiently supplied with nutrients and a corresponding Siognal is issued. If the maximum of a measurement curve lies between the two limit values O and U, the leaf is poorly supplied with nutrients, a corresponding signal is issued and fertilization should be carried out promptly.

It has been shown that a measurement in a period of time Ät2 is sufficient, the period of time Ät2 begins after a period of time Ät3 after the irradiation. Furthermore, it has been shown that a measurement period Δt2 of 20 ms is particularly suitable for a waiting period Δt3.

Alternatively, both a maximum and a minimum can be determined in the measurement period Δt2. A quotient is then determined from this, which is a criterion for the fertilization status. With suitable

Period of time Ät2, the minima differ with different

Fertilization conditions are insignificant, while the maxima differ significantly. A small quotient is therefore a signal for a lower fertilization status than a larger quotient.

[0044] It can be advantageous to encapsulate the transmitter /

Receiver and the sheet to avoid exposure to light

provided, since ambient light is brighter than the fluorescent reflection. Without such an encapsulation, a frequency filter is necessary in order to measure only the fluorescent reflection.

The receiver 3 is advantageously equipped with a frequency filter

combined to just the fluorescent reflection with a

Select wavelength from the received signal.

According to the invention, a basic signal can be present in the measurement method, which is reduced by the fluorescent reflection. In this case, if the leaf is sufficiently fertilized, the value falls below a certain limit, while if there is an acute nutrient deficiency, another

Limit value is not fallen below.

By connecting the device 1 to a computer, mobile phone 7, tablet or other device, the measurement result can be processed in a corresponding program or app and the result can be displayed. The connection is preferably made wirelessly, for example via a connection in accordance with the IEEE 802.5 standard / Bluetooth. For a simplified visualization, a green signal for sufficient fertilization, a red signal for immediate fertilization, can be compared to a traffic light

Fertilizer requirement and yellow or orange for a state in between. Optionally, the evaluation unit 5, the time recording 4 and the

Data storage 6 be part of the computer, mobile phone 7, tablet or other device. Then at least the

Light source 2, the receiver 3, a control unit and the transmitter 11 are connected to one another.

A fertilizing device can also be controlled via a data connection in order to cause fertilization in the event of a lack of fertilizer.

Figures 3 to 5 show metrological tests to demonstrate the effectiveness of the method according to the invention.

The figures show that fertilized plants in the kinetics of

differentiate modulated reflection at 820 nm from unfertilized.

FIG. 4 shows a comparison of plants that were darkened for 20 minutes before the measurement with plants that were measured directly in normal ambient light. Here it can be seen that as executed a

Darkening is not necessary for the measuring method according to the invention.

With reference to FIGS. 3 to 5, and in particular FIG. 3, it becomes clear that fertilized plants differ from unfertilized plants in the kinetics of the modulated reflection at 820 nm.

As an extreme example, the measured values from Venus flytraps are integrated in FIG. Venus flytraps grow on swampy soils with poor nutrient availability, so in the course of evolution they have developed trapping leaves to provide themselves with nutrients through the digestion of insects. The minima of Venus flytraps fertilized via the soil in the measurement curves approach those of normal plants after fertilization.

Claims

1. Device (1) for detecting the fertilization status of plants with a

Light source (2), a receiver (3) and an evaluation unit (5), wherein the evaluation unit (5) is connected to a time recording (4) and a data memory (6), and wherein the light source (2) is designed and set up, To send light with a wavelength of 780 and 880 nm, in particular from 800 to 860 nm, preferably 820 nm, and the receiver (3) is designed and set up to transmit light with a wavelength of 780 and 880 nm, in particular from 800 to 860 nm, preferably 820 nm to receive.

2. Device (1) for detecting the fertilization status in the plant according to claim 1, characterized in that the transmitter and receiver a

Encapsulation is arranged.

3. Apparatus according to claim 1 or claim 2, characterized in that the receiver (3) is designed in the form of a PIN photodiode, photomultiplier and / or an avalanche photodiode.

4. Device according to one of the preceding claims, characterized

marked that

a further light source is included as a photosynthesis light source, which is designed and configured to emit light with a wavelength of 500 and

1000 nm, in particular from 550 to 800 nm, preferably 630 nm, the photosynthesis light source, in particular partially or completely, being operated parallel to the light source (2).

5. Device according to one of the preceding claims, characterized in that

a further light source is included as a photosynthesis light source, which is designed and set up to generate light between 350 and 900 nm

to radiate.

6. A method for recognizing the fertilization status in plants with a device which contains at least one light source, a receiver, a time recording and an evaluation unit, the light source for a first

predetermined period Ati sends a light signal, after the first

predetermined period Ati the receiver receives a signal for a second predetermined period At2 and records it as a function of time, in this second predetermined period At2 a quotient between the minimum and maximum signal is determined or an extreme value of the signal is compared with at least one threshold value and a signal corresponding to the result is issued for the fertilization status.

7. The method for detecting the fertilization status in plants according to claim 6, characterized in that the light source (2) sends light with a wavelength of 780 and 880 nm, in particular from 800 to 860 nm, preferably 820 nm.

8. The method according to claim 6 or 7, characterized in that

the time period At2 between 0.7 milliseconds and 100 milliseconds, preferably between 8 milliseconds and 40 milliseconds, in particular between 8 milliseconds and 20 milliseconds.

9. The method according to claim 8, characterized in that

the minimum in this area is selected as the measured value for the fertilization status.

10. The method according to any one of claims 6 to 9, characterized in that a further light source emits light with a wavelength of 500 and 1000 nm, in particular from 550 to 800 nm, preferably 630 nm, wherein the further light source, in particular partially or completely, parallel to the emission of the light signal in the specified time period Ati sends out a light signal.

11. The method according to any one of claims 6 to 10, characterized in that the device (1) is connected to a computer, mobile phone (7), tablet or another device, the connection preferably being wireless.

12. The method according to any one of claims 6 to 11, characterized in that a fertilizing device is controlled with the device (1).

13. Use of a device according to one of claims 1 to 5 for

Carrying out a method according to one of Claims 6 to 12.