soil chemistry sensor, plurality of soil chemistry sensors, method of collecting soil chemistry data

专利摘要:
SOIL CHEMISTRY SENSOR. We describe a soil chemistry sensor for detecting soil chemistry at the site, the sensor comprising a probe incorporating a first electrode (ion selective electrode) and a second electrode (reference electrode), in which said ion selective electrode comprises a first electrode housing defining a first lumen having an ion selective buffer towards a distal end, said first electrode including a first conductor in a first electrolyte, wherein said reference electrode comprises a second electrode housing defining a second lumen having a porous reference electrode plug towards a distal end, said second electrode including a second conductor in a second electrolyte, wherein said ion selective plug and said porous reference electrode plug are within a distance of 10 mm from each other, and each one of said porous reference electrode plug and said selective plug the ion compound comprises a polymer
公开号:BR112015014663B1
申请号:R112015014663-5
申请日:2013-12-20
公开日:2020-10-27
发明作者:Tonny Miller；Pierre-Henri LE BESNERAIS；Hugo MALAURIE
申请人:Plant Bioscience Limited；
IPC主号:

专利说明:

Field of the Invention
[001] The present invention relates to soil chemistry sensors, in particular to detect nitrate levels, and the manufacture and use of such sensors. Background of the Invention
[002] Inorganic fertilizers, in particular nitrogen-based fertilizers, have revolutionized agriculture. However effective management of the amount of fertilizer used on the land is important for many reasons including economic efficiency and environmental management - excess nitrogen drained from agriculture can fall into drinking water and cause significant problems for people's health, and can also harm fresh water and marine ecosystems. Several techniques are known to monitor the level of nitrate in the soil. Typically a soil sample is obtained, nitrogen is extracted, and this is then used to predict the amount of nitrogen available to plant roots in the soil. However, this is a lengthy process, typically involving taking several soil samples and waiting an average of two weeks for the results to return from the laboratory. Based on the results a farmer will decide, for example, how much nitrate-based fertilizer to use in a spring and / or autumn application.
[003] This procedure is laborious, slow and expensive and there is a need for improved techniques, and in particular effective, but relatively inexpensive techniques. Such techniques would also be of use in the developing world.
[004] Adamchuk et al. (Adamchuk, V., Lund, E., Sethurama-samyraja, B., Morgan, M., Dobermann, A. and Marx, D., 2005. Direct Measurement of Soil Chemical Properties on-the -Go using Ion-Selective Electrodes, Computers and Electronics in Agriculture, vol. 48, No. 3, pp.272-294) provide a relatively recent analysis of soil detection techniques, but all the techniques described there involve extracting a soil sample and subsequently analyze it in an aqueous solution. Ito et al. (Ito, S., Baba, K., Asano, Y., Takesako, H., 1996. Development of a Nitrate Ion-Selective Electrode Based on an Urushi Matrix Membrane and its Application to the Direct Measurement of Nitrate Nitrogen in Upland Soils, Taianta, vol. 43, No. 11, pp. 1869-1881) describe a selective nitrate ion electrode based on Urushi, a natural lacquer from the east. Previous work by one of the inventors (Miller, AJ and Zhen RG., Measurement of intracellular nitrate concentrations in Chara using nitrate-selective microelectrodes, Plant 1991 184: 47-52) describes the manufacture of selective nitrate microelectrodes to measure nitrate concentrations in plant cells.
[005] There is a need for improvements when measuring / monitoring the levels of nitrate (and other plant nutrients). Summary of the Invention
[006] According to the present invention this is provided [as in claim 1],
[007] The inventors have established that for detection of soil chemistry at the site, that is, detection when inserting the probe directly into the soil, a key difficulty in practice is to ensure effective operation of the reference electrode. In embodiments this is addressed by manufacturing the reference electrode membrane or membrane in a similar manner to that used for the ion selective electrode buffer / membrane, in particular by solvent molding a polymer material at the end of the lumen, for example example, high molecular weight PVC (polyvinyl chloride). In some preferred embodiments, this material includes one or more additives to decrease its electrical resistance.
[008] It has also been found to be important to keep the ion-selective and reference electrodes, more particularly their porous buffers, adjacent to each other, for example, separated by less than 20, 15, 10, 5, 3 or more preferable by less than 2 millimeters. This is because soil moisture content can vary and with larger spacing the results may not be reliable, becoming excessively dependent on the soil moisture level. In preferred embodiments, a fixation device is provided around the distal ends of the electrodes to prevent them from being pulled away during insertion into the ground.
[009] For the related reasons, it was also found to be important to build the waterproof sensor (except for porous plugs). Thus, preferably the ion detection and reference electrodes are sealed inside a waterproof wrap, in modalities manufactured by cold contraction tube: such material is able to achieve a watertight seal without the application of heat, which is important for practical probe manufacture.
[010] In some preferred embodiments the second electrode (reference electrode) is a double junction electrode, in particular including a second electrode chamber connecting to the first by means of a second porous plug, preferably also made of a material of polymer, in a manner similar to that of the external porous reference electrode plug. In practical tests the use of a double joint was found to provide more stable results (detection signals) and increased probe life, as well as better protection for the total probe when used inside the ground.
[011] In modalities, the soil chemistry sensor, more particularly the probe, incorporates a soil moisture detection device such as a pair of exposed electrical conductors. This allows the soil moisture content to be detected in such a way that, optionally, the signal from the ion selective electrode can be compensated with respect to the amount of soil moisture present. In principle, however, such soil moisture compensation can be performed using a separate sensor.
[012] In some preferred implementations the soil chemistry sensor is provided in combination with a high input impedance voltage sensor to detect the probe voltage. Advantageously a probe can be provided with a wireless data transmitter, for example, a Wi-Fi and / or mobile phone network transmitter for transmitting sensor data from the probe. Where a wired connection to the probe is employed this may tend to guide rainwater (along the outside of the wire) affecting local nitrate levels.
[013] In a preferred implementation a plurality of probes are connected to a shared data logger, which can have a wireless (shared) network connection to export captured data, via one or more voltage sensors (one sensor can be multiplexed through a plurality of probes). This facilitates, for example, for soil chemistry to be measured at multiple different depths within the soil such as, for example, 30 cm, 60 cm and 90 cm, and / or at multiple different locations within a field. This can provide improved data for more efficient fertilizer applications by varying the fertilizer application with location within a field and / or depending on a measured soil chemistry profile according to depth. In embodiments, a probe or set of probes may include a temperature sensor to adjust or compensate for measurement signals with respect to temperature for improved accuracy.
[014] The invention also provides a method of collecting soil chemistry data directly from the soil, in particular when inserting a probe into the soil as described previously.
[015] The use of a probe, or multiple probes, as previously described facilitates measuring / monitoring the actual levels of a plant nutrient in the soil, which can change very dynamically over time and / or with other conditions such such as humidity level and others.
[016] A low-cost sensor is desirable, for example, for applications in the developing world, and also when it is desired to position multiple sensors in an agricultural area. It has been found that effective electrodes can be manufactured from a disposable plastic pipette tip (for example, PVC or polypropylene). Preferably, the buffers are then formed by solvent-molding a new polymer, for example, PVC, as described above. In a case like this, it was found that increased reliability can be obtained by treating the lumen of an electrode on which the plug is being formed in order to increase its internal hydrophobicity. This can be achieved in several ways including, for example, by plasma treatment, but in a direct approach a polydimethylsiloxane emulsion, silica filler and non-ionic emulsifier (Dow Corning (RTM) Repelcote) is employed.
[017] Some preferred modalities of the soil chemistry sensor described above are used to detect soil nitrate level at the site, but depending on the ion selective material used in the first electrode buffer, other relevant chemicals for environmental monitoring and / or plant nutrition can also be detected, including, but not limited to: ammonium, potassium and phosphorus; Sensor variants can also be used to detect soil pH.
[018] In modalities, the soil chemistry sensor described above is used to identify a soil chemistry depletion zone around a plant root. A nutrient depletion zone develops around a root when nutrients are removed from the soil solution more quickly than they can be replaced by the movement of nutrients through the solution. For example, ions that have low mobility in the solution can produce a sharp / narrow depletion zone near the root.
[019] In modalities, a plurality of soil chemistry sensors are used to determine soil chemistry data at a plurality of depths in a soil sample. This can enable determination of how chemicals move through the soil (without any plants), and / or how chemicals are absorbed by plant root systems. For example, roots close to the surface of the soil can absorb chemicals in the soil at a different rate than those deeper in the soil.
[020] The soil chemistry sensors described so far are capable of measuring soil chemistry at the site at a certain distance below the surface of the soil, where the distance itself (ie depth) is limited by the length of sensor / sensor electrodes. It may be desirable to measure soil chemistry at greater depths in a soil structure in a field, and / or to measure soil chemistry at multiple different depths in a soil structure simultaneously, and / or to obtain soil chemistry data in time real on the spot. If real-time measurements indicate that fertilizer needs to be added to the top of the soil, but that the soil is prone to leaching, then a farmer can use the information to decide when to irrigate after applying fertilizer to his crops to minimize the effect of water take away the nitrates near the top of the soil surface.
[021] Thus, an aspect of the present invention provides a probe for detecting soil chemistry at the site, the probe comprising: a housing extending longitudinally with a tip to penetrate the soil, said housing having at least one detection region, wherein said detection region comprises at least one detection membrane to allow ions from said soil to enter said probe, and wherein said detection region is on a side wall of said housing displaced from said tip (i.e., close, but not exactly at the tip) of said probe.
[022] In modalities, the detection region comprises a pair of said membranes, a reference membrane and an ion selective membrane, for respective reference and ion selective electrodes of a sensor inside said probe.
[023] In modalities, the sensor comprises electrolyte or conductive gel between each respective membrane and a respective electrode connection.
[024] A further related aspect of the invention provides a sensor for detecting soil chemistry at the site comprising a pair of membranes on a common surface, a reference membrane and an ion selective membrane for respective reference and ion selective electrodes of the sensor and electrolyte or conductive gel between each respective membrane and a respective electrode connection.
[025] One aspect of the invention provides a probe for detecting soil chemistry at the site, said probe comprising: one or more sensors of soil chemistry, wherein each of said one or more sensors of soil chemistry comprises: a first membrane (reference membrane) and a second membrane (ion selective membrane), a first electrical connection coupled to said first membrane (reference membrane); and a second electrical connection coupled to said second membrane (ion selective membrane); wherein said first and said second electrical connection provide a soil chemistry detection signal; and a tube comprising one or more detection openings along a length of said tube, wherein one of said one or more sensors is provided in one of said one or more openings, and wherein said probe is capable of said detection of soil chemistry at one or more depths below a soil surface.
[026] In modalities, each of the soil chemistry sensors is fixed in a separable way to said tube in said openings.
[027] In preferred embodiments, the first membrane (reference membrane) and the second membrane (ion selective membrane) are close together, preferably within a distance of 2 mm from each other.
[028] In a related aspect of the invention, a method of providing nutrients to a plant is provided, said method comprising: inserting a probe, in particular as previously described, vertically into the soil near said plant; detecting soil chemistry at one or more depths below a surface of said soil; identifying depletion of said nutrients at said one or more depths below said surface of said soil; apply nutrients to said soil in response to said depletion.
[029] In modalities, the detection takes place at a first depth close to said surface of said soil and at a second depth more distant from said surface of said soil, and additionally in which said nutrients are depleted if said concentration of nutrients in the said first depth is relatively less than said concentration of nutrients in said second depth, preferably 10 times less.
[030] An additional aspect of the invention provides the use of a soil chemistry sensor / probe to determine when to apply fertilizer to a plant, the method comprising: detecting a nutrient level at a plurality of different depths in the proxies -mities of said plant, using the sensor / probe, in which said depths identify a nutrient depletion zone, said nutrient depletion zone comprising a region, defined by depth, where absorption of said nutrient by said plant is relatively bigger; determining a ratio of detected nutrient levels between at least two of said different depths to determine an absorption of said nutrient by said plant of a relative depletion of said nutrient at one of said depths with respect to another; and determining when to apply said fertilizer based on said determined ratio. Brief Description of Drawings
[031] These and other aspects of the invention will now be described further, just by way of example, with reference to the attached Figures where:
[032] Figure 1 shows a soil chemistry sensor according to a modality of the invention (the supplement shows a modality actually built);
[033] Figure 2 shows a calibration curve for the sensor in Figure 1;
[034] Figure 3 shows a sensor system incorporating multiple soil chemistry sensors of the type shown in Figure 1;
[035] Figures 4a to 4c illustrate soil chemistry sensors in a soil column;
[036] Figures 5a and 5b show soil nitrate data from measurements made using the soil column of Figures 4a-4c;
[037] Figure 6a shows soil nitrate depletion (absorption) data for two different crops;
[038] Figure 6b shows a variation in nitrate concentration in a vermiculite column at two different column depths;
[039] Figure 7 shows a schematic of a soil chemistry sensor to measure chemical depletion (absorption) near plant roots;
[040] Figure 8a shows a variation of depletion (absorption) of soil nitrate over time at different points around plant roots;
[041] Figure 8b shows a variation of depletion (absorption) of soil nitrate over time at different points around plant roots, and a variation in light over time;
[042] Figures 9a and 9b represent a soil chemistry sensor according to the modalities of the invention;
[043] Figures 9c and 9d represent a soil chemistry sensor comprising side membranes according to an alternative embodiment of the invention;
[044] Figures 9e and 9f illustrate construction steps to form the side membranes of Figure 9d;
[045] Figures 9g and 9h illustrate construction steps to seal the soil chemistry sensor in Figure 9d;
[046] Figure 10a shows a probe comprising a vertical soil chemistry sensor for measuring soil chemistry within a soil structure, according to an embodiment of the invention;
[047] Figures 10b and 10c illustrate construction of the probe of Figure 10a;
[048] Figure 10d shows a probe comprising multiple vertical soil chemistry sensors to measure soil chemistry at multiple depths within a soil structure, according to an embodiment of the invention;
[049] Figure 11a shows a probe comprising multiple horizontal soil chemistry sensors for measuring soil chemistry at multiple depths within a soil structure, according to an alternative embodiment of the invention;
[050] Figures 11b and 11c represent two different arrangements for the horizontal soil chemistry sensors of Figure 11a;
[051] Figure 12a illustrates a probe comprising multiple 'key-type' soil chemistry sensors for measuring soil chemistry at multiple depths within a soil structure, according to an embodiment of the invention;
[052] Figure 12b shows an enlarged view of the 'key type' soil chemistry sensor of Figure 12a;
[053] Figure 12c illustrates a probe comprising multiple 'key-type' soil chemistry sensors for measuring soil chemistry at multiple depths within a soil structure, according to an alternative embodiment of the invention; and
[054] Figure 12d shows an enlarged view of the 'key type' soil chemistry sensor of Figure 12c. Detailed Description of Preferred Modalities
[055] Figure 1 shows a selective nitrate (NO3) 100 soil chemistry sensor according to an embodiment of the invention. The sensor comprises a selective nitrate electrode 102 and a double junction reference electrode 104. The ion selective electrode comprises a plastic lumen 106, in modalities manufactured from a disposable plastic pipette tip or syringe such as a poly syringe - low cost Propylene Distritip (RTM). An ion selective membrane 108 is manufactured at the electrode end by solvent-molding a polymer such as high molecular weight PVC in combination with an ion charger. For example, for nitrate detection a suitable ion carrier is tridodecylmethylammonium (TDDMA) nitrate, however additionally or alternatively other selective ion components can be employed to detect additionally or alternatively other plant nutrients. The membrane composition can be dissolved, for example, in tetrahydrofuran (THF).
[056] An example ion selective composition for making a nitrate selective membrane is as follows: 1.50% by weight of Tridodecylmethylammonium nitrate; 16.25% by weight of 2-Nitrophenyl octyl ether; 1.93% by weight of nitrocellulose, 35% in isopropanol; 0.25% by weight of methyltriphenylphosphonium bromide; 5.75% by weight of high molecular weight polyvinyl chloride; 74.32% by weight of Tetrahydrofuran.
[057] Preferably, the plastic interior of the lumen is treated with a silanization solution such as Dow Corning (RTM) Repelcote to improve the hydrophobicity of the plastic surface, and to improve the seal between the solvent molded membrane and the lumen. After this has dried completely, the lumen end portion is filled with the dissolved ion selective composition and the THF is allowed to gradually evaporate over a number of hours at room temperature. The electrode is then filled with an electrolyte 110 comprising, for example, 100 mM KCI + 100 mM KNO3, within which an Ag / AgCI electrode wire (chlorinated silver) 112 is located.
[058] Preferably, reference electrode 104 is a double junction reference electrode comprising a pair of plastic lumens 114a, 114b, each with a solvent molded reference membrane 116a, 116b manufactured as described above, except that The TDDMA nitrate ion carrier is omitted. The reference membrane composition can also include one or more additives to improve the electrical conductivity of this membrane.
[059] In the double junction reference electrode, different external filling solutions 118a and internal 118b are used. The internal filling solution can be 100 mM KCI; the external filling solution can comprise, for example, 100 mM ammonium sulfate (for nitrate detection) or 100 mM magnesium sulfate (for NH4 detection) or 100 mM sodium chloride (for potassium detection). Additional examples of solution compositions, to detect different ions, and pH, are given later.
[060] In some preferred embodiments, the ion selective and reference electrode tips are fixed at 120 together by means of tape and / or rubber gloves; preferably the membrane tips are only 1-2 mm apart. It is also important that the probe is waterproof, and this was achieved by sealing the probe with 0 cold shrink tube 122 (a pre-stretched elastomer that contracts by removing the support core during application), in combination with sealer of silicone. This provided an effective seal without the need for heating, which could damage the electrodes.
[061] As shown schematically in Figure 1, the silver / silver chloride electrode wires 112 are coupled to a voltmeter of high importance in impedance, for example, a differential electrometer. The potential across wires 112 is a function, for example, of the selected nitrate ion concentration. The closer to 100 mM nitrate (the level of nitrate ions in the solution at the ion selective electrode) the closer to 0 V is the potential. When the concentration of nitrate (or another ion) in the external environment decreases, the voltage increases, according to a variation of the Nernst equation, the Nickolsky-Eisenman equation (which considers ion interference other than the target ion): E = K + (2,303RTZziF) log (ai + kijajzi / zj)
[062] where E is the potential, Zi and a; are the ion charge and activity of interest, K is a constant dependent on the probe design, R is the gas constant, T is the Kelvin temperature, F is the Faraday constant, j identifies the interfering ions and Kj is the selectivity coefficient - a quantitative measurement of the electrode's ability to discriminate against interfering ion j.
[063] Before use the probe is calibrated using a set of nitrate solutions that have a constant background ionic strength, for example, with nitrate activity of 100 mM (pNO3), 10 mM, 1 mM, 0.1 mM and 0.01 mM. Figure 2 shows an example calibration curve where the points are the stresses measured at the different nitrate concentrations and the line is a Nickolsky-Eisenman curve fitted to the following equation: f = P1 + P2 * log (10A (- x) + P3)
[064] In this equation the P2 slope is approximately 58 mV and the P3 value defines the limited probe detection (in M). Figure 2 shows two curves, a second curve with 10 mM KCI added to each nitrate solution. Chloride ions can interfere with selective nitrate membranes, but the two curves in Figure 2 are substantially coincident, showing that the presence of chloride ions has almost no effect on measurements of probe modalities.
[065] The following table shows an example of a set of soil chemistry measurements made using a probe modality - stable and consistent readings were obtained.

[066] Time series measurements can establish the effectiveness of nitrate absorption by plants in the soil under test. Calibrations before and after time series measurements indicated little or no deviation in the probe data.
[067] Monitoring the actual levels of nitrate in soil shows that they vary very substantially over time and with a location, even within a single field. It is desirable to be able to track these variations and / or monitor levels of nitrate (or other plant nutrient) at different depths within the soil such as, for example, 30 cm, 60 cm and 90 cm deep.
[068] Figure 3 shows an embodiment of a system 300 including a plurality of probes 100a-100n, each as previously described, each coupled to a respective voltage amplifier 302a-302n that provides voltage data to a voltage recorder. data 304. In this example the probes are coupled to the data logger via a wired connection that is used to power the probes / amplifiers, but in other modalities a wireless connection can be used. The data recorder 304 preferably incorporates the non-volatile memory 306 to store the collected data and an RF transceiver 310, for example, to communicate with a computer or mobile phone network, to provide a link to a computer / collection network / remote data analysis. A power supply 308 for the system may comprise, for example, a rechargeable battery, optionally powered by a renewable energy source such as wind or solar energy.

Additional Example Compositions
[069] Additional example ion selective compositions for making other ion selective membranes are given below. Preferably, high molecular weight polyvinyl chloride (PVC) is used on all membranes. Ammonium
[070] An example ammonium sensor component is nonactin, sold by Sigma-Aldrich (ammonium ionophore I). The electrode detection limit is 11 pM ammonium, but high K + can interfere with the response.
Calcium
[071] An example calcium sensor component is again sold by Sigma-Aldrich as a calcium ionophore II (product number 21193).
Potassium
[072] An example ammonium sensor is 90% (by weight) of potassium ionophore cocktail and 10% (by weight) of PVC polymer. The potassium ionophore cocktail contains: 5% by weight of potassium ionophore valinomycin (Sigma, product number 60403); 93% by weight of 1,2 dimethyl-3-nitrobenzene (Sigma, product number 40870); 2% by weight of potassium tetrakis (4-chlorophenyl) borate (Sigma, product number 60591).
Phosphate
[073] An example phosphate sensor component can be based on the phosphate sensor from Carey CM & Riggan WB Anal Chem. 1994 Nov 1; 66 (21): 3587-91, a cyclic polyamine ionophore for use in a dibasic phosphate selective electrode. Additional details can be found in EP2376442A, for which reference can be made. The composition is similar to that used for nitrate.

[074] In addition, reference can be made to Kim and other 2007 Transactions of ASABE 50 (2): 415-425 which shows that similar cobalt sensors can be manufactured. pH (protons)
[075] An example pH-sensing molecule is ETH1907 (hydrogen ionophore II), commercially distributed by Sigma-Aldrich. Like the nitrate-sensing mixture, this pH cocktail is made with a PVC and solid matrix of nitrocellulose, 62% of pH cocktail, 28% of PVC and 10% of absorbent nitrocellulose (Sigma-Aldrich, product code Sigma N8267 ).
[076] A suitable cocktail mix (as in the table below) is sold by Sigma-Aldrich (product code 95297).
Sodium
[077] Regarding sodium reference can be made to Carden and others 2001 (J. Exp. Bot. 52: 1353) who describe an improved sodium sensor (improved Na + to K + selectivity).
Use of Soil Chemistry Sensor to Detect Chemical Variation at Different Depths
[078] Turning now to Figures 4a to 4c, these illustrate a soil column system 400, according to an embodiment of the invention.
[079] As shown in Figure 4a, the soil column system 400 comprises a soil column 412 which is used to contain a volume of soil 414. One or more holes 410a, 410b, 410c are formed in soil column 412 at different points along the length of the column. One or more holes 410a, 410b, 410c are provided for one or more soil chemistry sensors. The soil column system enables measurement of soil chemistry at different depths in the soil 414. Advantageously, this can enable determination of how chemicals move through the soil (without any plants), and / or how chemicals are absorbed by plant root systems. For example, roots near the top of the soil column 412 can absorb chemicals in soil 414 at a rate different from that of deeper roots in the soil column.
[080] A soil sensor comprising a selective nitrate electrode and a double junction reference electrode (as described above) is inserted into a 410 hole to enable measurement of soil chemistry. In preferred embodiments, the soil column 412 comprises the three holes 410a, 410b, 410c and a soil sensor is inserted in each hole to enable measurements of soil chemistry to be considered at three depths, for example, near the top of the volume of soil 414 (that is, for shallow / surface roots), intermediate along the length of the soil column 412 and near the bottom of the soil volume 414 (that is, for deep roots). Preferably, the soil chemistry sensors are placed at 30 cm, 60 cm and 90 cm below the soil surface. As shown in Figure 4a, bore 410 is adapted to the shape of the soil sensor electrodes, such that an electrode can be inserted into part 416a of the hole, and the second electrode can be inserted into a second part 416b the hole. Thus, hole 410 matches substantially the size of the plastic lumen of the electrodes, to help seal the hole and minimize any leakage of soil or soil water out of hole 410.
[081] Figure 4b shows a soil column system 400 comprising the three soil sensors 418a, 418b, 418c in three different positions along the soil column. Figure 4c illustrates the soil column system 400 being used to measure soil chemistry at different depths. The silver electrode / silver chloride wires from each sensor are connected to a data logger and to a high-voltage voltmeter at impedance 420 (for example, a differential electrometer).
[082] Figures 5a and 5b show soil nitrate data from measurements made using the soil column system (the three sensors) in Figures 4a-4c. The soil column system was used to compare the nitrate absorption of two wheat crops: Robigus, which is known to have a high efficiency of nitrate absorption, and Maris Widgeon, which is known to have a low efficiency of nitrate absorption. Figures 5a and 5b respectively represent the variation of nitrate depletion in the soil column over time at different depths in a column containing the Maris Widgeon culture, and in a column containing the Robigus culture. In both cases, soil nitrate concentrations were measured by the soil column system at three depths over a period of 14 hours. The soil column system not only verifies the known nitrate absorption efficiency of the two crops, but it also advantageously enables a better understanding of how the root systems of the two crops behave. For example, the locations of the soil nitrate sensors in the soil column system show that the roots of the Robigus wheat variety appear to absorb nitrates through their shallow roots (that is, those at the top of the soil column). This can be useful information for wheat growers, as it indicates that for particular varieties of nitrate-rich fertilizer wheat it must be added frequently to the soil surface, while this may not be necessary for other varieties.
[083] Thus, knowing the nitrate level at different depths in the soil / growth medium can help to optimize the amount of fertilizer to add to the soil to promote growth while also minimizing leaching (ie loss of water-soluble nutrients by ground). For example, a low nitrate concentration measured near the top of the soil surface (for example, 30 cm from the soil surface), may trigger the need for more fertilizer to be added. In particular, an activation to add more fertilizer may be that the nitrate concentration at 30 cm below the soil surface is, for example, 10 times less than that at 60 cm or 90 cm below the soil surface. However, a high nitrate concentration (for example, 5 times above the expected concentration of 15 mM) at 90 cm can also be indicative of leaching. Thus, nitrate levels measured by soil chemistry sensors can also be used to make decisions regarding irrigation. For example, if measurements indicate that fertilizer needs to be added to the top of the soil, but that the soil is prone to leaching, then a farmer can use the information to decide when to irrigate after applying fertilizer to minimize the effect of water taking away nitrates near the top of the soil surface. Use of a Soil Chemistry Sensor to Detect Chemical Variation in a Hydroponic Culture
[084] The soil chemistry sensor previously described in modalities can be used to measure nutrient absorption in a hydroponic growth culture. Figure 6a shows nitrate depletion (absorption) data for two different crops in a hydroponic culture, that is, in a solution of mineral nutrients (such as opposite to the soil). In such modalities, it is essential that the sensor is waterproof (except for the porous plugs), and the ion detection and reference electrodes can be sealed within a waterproof wrap (for example, a wrap made contraction tube). Use of a Soil Chemistry Sensor to Detect Chemical Product Variation in an Artificial Growth Medium
[085] In modalities, the soil column system 400 shown in Figure 4a can be adapted for a vermaculite growth medium and the soil chemistry sensors used to detect chemical variation in the vermiculite column at different depths . Typically, exfoliated vermiculite (a hydrated silicate mineral) is combined with other materials such as peat or pine bark to form a growth medium without soil. Vermiculite-based media are known to promote faster root growth because the mixture helps to retain air, plant food and moisture and releases them as the plant requires it. Thus, the vermiculite column system was used to determine how nitrates move through the profile of the artificial growth medium.
[086] Figure 6b shows a variation in nitrate concentration in a vermiculite column at two different column depths. The data was collected using a column without any plants in order to determine the change in nitrate concentration because of movement through the growth medium alone (that is, without the effect of absorption by a plant). Nitrate was added to the top of the vermiculite column at time t = 0. The data indicates that nitrates flow relatively quickly through the growth medium to reach the central part of the column.
[087] Consequently, as previously described, the soil chemistry sensor can be used to: - Provide measurements of soil chemistry quickly, on a fine scale and in real time; - Measure chemical / nutrient absorption directly in hydroponic solutions; - Measure chemical depletion (for example, nitrate) to predict chemical absorption by plants directly into the soil at one or more depths; - Determine the effects of soil moisture gradients on the absorption of chemical products (for example, nitrate); - Identify which fraction of the root system is active in the absorption of chemical product during the development stages of a plant; and - Determine the movement of nitrate through the soil or a solid substrate (for example, vermiculite) to determine leaching behavior. Use of Soil Chemistry Sensor to Measure Soil Chemistry Depletion Zones Around Plant Roots
[088] In modalities, the soil sensor described above can be used to identify 'depletion zones' around the roots of a plant. A nutrient depletion zone develops around a root when nutrients are removed from the soil solution more quickly than they can be replaced by the movement of nutrients through the solution. For example, ions that have low mobility in the solution can produce a sharp / narrow depletion zone close to the root.
[089] Now returning to Figure 7, this represents a schematic of a soil chemistry sensor to measure chemical depletion (absorption) around plant roots, that is, to identify a depletion zone around the roots. The depletion zone measuring device 700 comprises a container 710 containing the soil solution or growth medium. A single plant 714 is planted in container 710. To measure nutrient uptake by the roots, the plant roots are contained within the dialysis tube 712. In the illustrated embodiment, two sensors are provided within the dialysis tube 712, to measure changes in nutrient levels close to the plant roots, and two sensors are provided in container 710 away from the dialysis tube 712, to measure changes in nutrient levels in the soil / growth medium away from the plant roots.
[090] In an example embodiment, sensor B is placed 2 cm below the ground surface and sensor K is placed 6 cm below the ground surface, where both sensors B and K are provided inside the dialysis tube 712 (that is, close to the roots). Further away from the dialysis tube / roots are the H sensor, placed 2 cm below the soil surface, and the I sensor, placed 6 cm below the soil surface. The four sensors together measure changes in soil chemistry at two different depths within container 710 and at two different distances from the roots. The device was used to measure changes in soil chemistry and the depletion zone around wheat roots. Container 710 was filled with a sand culture with nutrient solution added as the growth medium.
[091] Figures 8a and 8b show data collected using this device over a period of four days and data collected over a period of fourteen days. Figure 8b also illustrates changes in light during the fourteen day period, which corresponds to the day / night cycle. The data show that, for this particular wheat variety, nitrates are absorbed by the roots at approximately the same rate at 2 cm and 6 cm below the soil surface. They also show that, as nitrates are being depleted near the roots, nutrients are dragged towards the roots through the dialysis tube (that is, nutrients are depleted around sensors H and I). Over fourteen days, nitrates were depleted in volume close to the plant roots. The nitrate concentration in the shallow crop furthest from the roots was also depleted over this period. Such data can be used to estimate the depletion zone around plant roots, which in this case can be a few centimeters (for example, 1 to 2 cm) from the surface of the roots.
[092] Consequently, the soil chemistry sensor can be used to: - Measure soil chemistry / complete nutrient depletion on the root surface; - Identify soil chemistry / nutrient depletion zones around the root; and - Measure daytime changes in soil chemistry / nutrient depletion (nutrient absorption). Electrode Design
[093] Figure 9a shows a variation of the soil chemistry sensor in Figure 1. In this embodiment, the soil chemistry sensor 100 additionally comprises one or more holes 926. The "breather holes" 926 are formed in the selective electrode of nitrate 102 and the double junction reference electrode 104, to equalize the pressure inside the electrodes 102 and 104 and the outside of the electrodes, particularly when being transported in a pressurized environment, such as in an airplane. Vent holes 926 can be larger than 1 mm in diameter. However, to minimize the risk of foreign matter (eg water / soil water) entering the sensors through the 926 breather holes, the holes are preferably "pin holes" and <1 mm in diameter. Alternatively, the 926 breather holes can be replaced by valves or taps to allow pressure equalization and prevent foreign matter from entering the sensor. Figure 9a also shows how the electrodes are sealed to prevent soil water from entering the electrodes through the top of sensor 100. A plug 928, which can be formed of a flexible and / or water-resistant material, is inserted at the top each electrode 102 and 104 around wires 112 to form a seal. In this embodiment, the ends of the electrode wires 112 are not encased in the sealer or plugs 928, but preferably a cable ferrule 930, such as a shoelace ferrule, is used to form an end termination of each wire 112. Thus , the cable ferrule 930 is not protected / insulated against any water that may leak through the top of the sensor 100. The coupling between the electrode wires 112 and a high impedance voltmeter (not shown) is provided by the wire connections 934 standards.
[094] Now returning to Figure 9b, it shows an additional variation of the soil chemistry sensor in Figures 1 and 9a. The sensor 900 comprises a selective nitrate electrode 902 and a double junction reference electrode 904, where the double junction reference electrode comprises the different external 918a and internal 918b filling solutions. Each electrode contains a 912 electrode wire. As mentioned earlier, it is important to make the soil chemistry sensor waterproof (except for porous plugs). Thus, the ion detection and reference electrodes are preferably sealed within a waterproof wrap. In particular, top seal of the sensor is important to ensure that ground water does not come into contact with the sensor circuitry. In embodiments, the lead wire from each electrode passes through a plug 928 provided to seal the top of each electrode 902 and 904. Preferably, plug 928 is plastic and / or formed of a flexible water-resistant material, and forms a seal watertight to prevent soil water from entering the electrode from the upper end and protects the exposed lead wire 112 from external environmental conditions. In the embodiment shown, each cable ferrule 930 is partially enclosed in a plug 928 and an additional seal 932 is arranged above the plug 928 to provide an additional seal and to protect the cable ferrule 930 from water damage. Sealer 932 can be a water-repellent adhesive such as putty that can be pressed into each electrode to form a seal above cap 928. Thus, no metal from each electrode is in contact with the soil / water of soil on which the electrode is placed.
[095] The soil chemistry sensor in Figure 9b does not comprise "breather holes" as in the embodiment shown in Figure 9a. Advantageously, the lack of breather holes minimizes the chance of the electrode solutions mixing with external water / soil water, which also prevents the chance of the 900 sensor shorting.
[096] An additional sealer (not shown), for example, a glue or adhesive material, can be used to reinforce the double junction reference electrode seal (s) 904 in order to prevent the reference solution 918a, 918b leaks out of their respective chambers. Preferably, rubber glove 920 is repositioned with respect to the position of glove 120 shown in Figure 9a, to further reinforce the double junction electrode 904.
[097] As previously described with reference to Figure 1, each electrode of the soil chemistry sensor 100 is manufactured from a pipette tip with a hole in the tip end to allow liquid to enter and exit the pipette tip. Thus, the borehole enables soil water and nutrients to contact the reference / ion selective membrane and be detected by the soil chemistry sensor. However, inserting the soil chemistry sensor vertically down into the soil can damage the pipette tip and membrane. An alternative embodiment is shown in Figures 9c and 9d, which show a soil chemistry sensor 9000 comprising membranes 942 along one side of each pipette tip. The soil chemistry sensor 9000 is formed by an ion selective electrode 902 and a single tip reference electrode 940, where each electrode is formed by a pipette tip as previously described (although not shown, the reference electrode 940 can be a double junction reference electrode). Holes are formed on the pipette tip side of each electrode and the 942 ion selective and reference membranes are formed in the holes. Thus, even if the tip of the pipette tip is damaged when the soil chemistry sensor is inserted into the soil, the 942 holes and membranes will not be damaged and for this reason the electrodes are not prevented from performing their detection function.
[098] As shown in Figure 9d, preferably, the membrane 942 of each electrode is positioned in such a way that the membranes confront each other. This may require electrodes 902 and 940 to be rotated from a side-by-side orientation, as shown in Figure 9c, to a face-to-face orientation as shown in Figure 9d. It is preferable that electrodes 902 and 940 are close to each other (so that each one measures soil chemistry at approximately the same position in the soil structure), but that they are also isolated from each other to prevent short-circuiting. Thus, as previously described, electrode wires 912 and any connectors (metal) (for example, a cable ferrule) holding the wires in place are insulated by plug 928 and sealer 932, which also protects the wire and connectors against exposure to external conditions (eg soil water). In particular, the separation distance between the membranes of the electrodes 902 and 940 should be minimal, particularly when taking measurements on site, as the soil structure and / or porosity can modify the water available for detection by each of the electrodes. Thus, preferably the distance between the membranes is between 1-2 mm. Most preferably, the distance A between the tips of each electrode is greater than the distance B between the membranes 942 when the membranes are side by side (as in Figure 9c), and the distance B is greater than the distance C when the membranes 942 are face to face (as in Figure 9d), that is, A> B> C.
[099] Now returning to Figures 9e and 9f, these represent the plastic lumen 944 of the side membrane soil chemistry sensor 9000 in Figure 9d. As mentioned earlier, typically, a pipette tip 944 has a hole 946 at one end to allow liquid to enter and exit the pipette tip. To form the side membranes of the 9000 soil chemistry sensor, hole 946 of each pipette tip is sealed using a soldering iron and one or more holes 942 are formed along the length of the piercing tip instead of na tip. The holes can be formed using a hot needle that is inserted into the 944 pipette tip at desired locations. The membrane is formed as described above.
[0100] In modalities, the 9000 soil chemistry sensor of Figures 9c and 9d can be covered with a plastic or water resistant material to provide an insulating and waterproof layer over the 9000 sensor. Techniques such as Plasti-Dip can be used to provide the layer. Preferably, the layer covers everything but the electrode membranes.
[0101] In modalities, the 9000 soil chemistry sensor can be formed with an additional protective cover over the wires extending outside the electrodes. As shown in Figures 9g and 9h, a pipette tip 950 is attached to the electrodes in such a way that the wide end contacts the sealer 932 and the connecting wire 934 exits through the narrow end / tip of the pipette tip 950. The tip of the pipette 950 prevents the connections between the electrode wire and the 934 connection wire from being damaged. A protective rubber glove 948 is provided over the 950 pipette tip to hold the pipette in position and to provide a degree of flexibility for the connection between the electrode and the 934 wire. A plastic coating, as shown in Figure 9h , can be provided over the 950 pipette tip to provide an insulating and waterproof layer over the connection. The plastic coating can be formed using the Plasti-Dip technique or otherwise.
[0102] As previously described, each ion-selective and reference electrode is made of a plastic lumen, which in modalities is formed from a low-cost disposable pipette tip. Another advantage of using a disposable pipette tip over a plastic syringe is that the small pipette tip ensures that a smaller surface area of the ion selective membrane comes into contact with the soil water, and so the risk of damage to the membrane is reduced. On-site Soil Chemistry Measurement at Different Depths with Vertical Sensors
[0103] The soil chemistry sensors described so far are capable of measuring soil chemistry at the site at a certain distance below the surface of the soil, where the distance itself (ie, the depth) is limited by the length of the sensor / sensor electrodes. The soil column system shown in Figure 4a is suitable for measuring soil chemistry within the soil column, that is, for a plant growing inside the column, but it is not suitable for measurements on site (for example, in a field) . It may be desirable to measure soil chemistry at greater depths in a soil structure in a field, and / or to measure soil chemistry at multiple different depths in a soil structure simultaneously, and / or to obtain soil chemistry data in time real on the spot. If real-time measurements indicate that fertilizer needs to be added to the top of the soil, but that the soil is prone to leaching, then a farmer can use the information to decide when to irrigate after applying fertilizer to his crops to minimize the effect of water take away nitrates that are near the top of the soil surface.
[0104] Figure 10a shows a variable length probe 1000 comprising a vertical soil chemistry sensor for measuring soil chemistry within a soil structure, according to an embodiment of the invention. The 1016 soil chemistry sensor is substantially similar to that shown in Figure 9b, and comprises an ion selective electrode, a double junction reference electrode, a 1020 plug and a sealer 1022 to seal each electrode. The probe 1000 is made up of three main parts: a non-porous tube part 1008, an adapter part 1010 and a porous cap part 1014. The non-porous tube part 1008 is provided by a tube or pipe of the required length to place the soil chemistry sensor at a particular depth below the soil surface. Thus, advantageously, probe 1000 has an adjustable length, which is adjusted by constructing the probe from a portion of non-porous tube 1008 of the required length to place the sensor at the required depth. The pipe part 1008 can be provided by an insulating and waterproof material, for example, a plastic pipe / pipe, to protect the top of the soil sensor 1016 and the electrical wiring 1006 against contact with the external environment (for example, water / soil water). The porous cap part 1014 is formed of a porous material, for example, ceramic, to enable soil water to enter probe 1000 for detection by the soil chemistry sensor 1016 contained within probe 1000. As shown in more detail in enlarged view of the sensor end of probe 1000, the porous cap part 1014 contains a reservoir of liquid (water) 1018. Electrolytes / ions in the soil outside the porous cap part 1014 flow into the reservoir 1018, enabling the 1016 soil chemistry sensor to measure soil chemistry through reservoir 1018 instead of direct contact with the soil.
[0105] The adapter part 1010 couples the non-porous tube part 1008 and the porous cap part 1014 together. In addition, adapter 1010 holds the soil chemistry sensor 1016 in an upright position within the cap part 1014. A circular seal 1012 inside the adapter 1010 either holds the soil chemistry sensor 1016 in place inside the cap part 1014 or forms a waterproof seal to prevent fluid in reservoir 1018 from leaking out of cap part 1014 and between in contact with the wiring 1006 in the pipe part 1008. Preferably, the seal 1012 is formed of a water resistant material such as rubber.
[0106] As shown in Figure 10a, probe 1000 is inserted into the soil structure in such a way that the sensor end of the probe is at the desired depth at which measurements are to be taken. The probe 1000 is sealed at the top end with a rubber breadboard 1004 and a plastic cap 1002 to prevent water / foreign matter from entering the pipe part 1008 and contact wiring 1006. Wiring 1006 runs through plug 1004 and cover 1002 to connect the electrodes to a 1024 data logger.
[0107] Figures 10b and 10c show external views of the probe of Figure 10a, and in particular show the three main parts of probe 1000. The porous part 1014 can be separably coupled to the adapter part 1010, for example, by means of a screw connection (not shown). Similarly, adapter part 1010 can be separably coupled to tube part 1008. Consequently, as mentioned earlier, probe length 1000 can be changed by selecting a part of tube 1008 of a particular length (or by changing the length of the adapter part 1010 or the porous cap part 1014). An additional advantage of probe 1000 is that the 1016 soil chemistry sensor can be readily removed from probe 1000 if the sensor is not working and / or to change the ion selective electrode to measure the presence of different chemicals in the soil.
[0108] Now returning to Figure 10d, it shows a probe 1000a comprising multiple vertical soil chemistry sensors, for measuring soil chemistry at multiple depths within a soil structure, according to an embodiment of the invention. In this fashion, probe 1000a comprises one or more sensor sections 1028 and a tip sensor section 1030. Each sensor section 1028 comprises a portion of non-porous tube 1008, an adapter portion 1010 and a porous portion 1026. The sensor section of tip 1030 comprises a part of non-porous tube 1008, an adapter part 1010 and a part of porous cap 1014. The length of each sensor section 1028 and the tip sensor section 1030 is changeable (for example, by changing the length of the tube 1008 as previously described), to perform soil chemistry measurements at two or more desired depths in the soil structure below the soil surface. The porous part 1026 can be separably coupled to the adapter part 1010, for example, by means of a threaded connection (not shown). Similarly, adapter part 1010 can be separably coupled to tube part 1008. Consequently, as mentioned earlier, probe length 1000a can be changed by selecting a part of tube 1008 of a particular length (or by changing the length of the adapter part 1010 or the porous cap part 1026).
[0109] One or more sensor sections 1028 can be separably coupled together to form probe 1000a, such that the porous portion 1026 of a sensor section 1028 is coupled to the pipe portion 1008 of an adjacent sensor section 1028. For example, probe 1000a illustrated in Figure 10d is capable of measuring soil chemistry at three different depths below the soil surface. Thus, the probe is formed from the two sensor sections 1028a, 1028b and a tip sensor section 1030. The first sensor section 1028a is used to detect soil chemistry at a depth A in the soil structure. As shown, the tube portion 1008 of the first sensor section 1028a is sealed using a rubber plug 1004 and the plastic cap 1002 to prevent water / soil water from entering the probe 1000a through the top of the probe. The porous part 1026 of the first sensor section 1028a is coupled to the tube part 1008 of the second sensor section 1028b. The second sensor section 1028b is capable of measuring soil chemistry at a depth B in the soil structure. The porous portion 1026 of the second sensor section 1028b is coupled to the tube portion 1008 of the tip sensor section 1030. The tip sensor section 1030 is capable of measuring soil chemistry at a depth C in the soil structure. The porous cap part 1014 of the tip sensing section 1030 forms the tip of the probe 1000a (i.e., sensing sections cannot be coupled to the porous cap part 1014).
[0110] As previously described with reference to Figure 10a, each soil chemistry sensor 1016 of each sensor section 1028, 1030 is retained by adapter 1010 in such a way that the ion and reference selective membranes are immersed in a reservoir of liquid contained within each porous part 1026 and 1014. Each porous part 1026 is manufactured in such a way that electrical wires from each sensor 1016 can pass through the porous part 1026 and extend outwards through the sensor top 1000a. In addition, each porous part 1026 is manufactured to minimize the risk of liquid from the reservoir within each porous part 1026 leaking into adjacent sensing sections. Consequently, the electrical wires can be covered with an insulating and waterproof material to prevent short circuits. On-site Soil Chemistry Measurement at Different Depths with Horizontal Sensors
[0111] Figure 11a shows a probe 1100 comprising multiple horizontal soil chemistry sensors for measuring soil chemistry at the site at multiple depths within a soil structure, according to an alternative embodiment of the invention.
[0112] In this embodiment, probe 1100 comprises one or more sensor sections 1152 and a tip sensor section 1154. Each sensor section 1152 comprises a non-porous tube part 1108 and a sensor part 1148 or 1150. The tip sensor section 1154 comprises a non-porous tube part 1108, a sensing part 1110 and a tapered tip 1122. The length of each sensing section 1152 and the sensing tip section 1154 is adjustable (for example, by selecting tube part 1108 with different lengths such as as previously described), to perform soil chemistry measurements at two or more desired depths in the soil structure below the soil surface. The sensor part 1148 or 1150 can be separably coupled to the tube part 1108, for example, by means of a threaded connection (not shown).
[0113] One or more sensor sections 1152 may be separably coupled together to form probe 1100, such that the porous portion of a sensor section 1152 is coupled to the tube portion 1108 of an adjacent sensor section 1152. For example, probe 1100 illustrated in Figure 11a is capable of measuring soil chemistry at three different depths below the soil surface. Thus, probe 1100 is formed from the two sensor sections 1152a, 1152b and a tip sensor section 1154. The first sensor section 1152a is used to detect soil chemistry at a depth A in the soil structure. As shown, the tube portion 1108 of the first sensor section 1154a is sealed by a rubber plug (not shown) and a plastic cap 1102 to prevent water / soil water from entering the probe 1100 from the top. The sensor part 1148 or 1150 (described in more detail below) of the first sensor section 1152a is coupled to the tube part 1108 of the second sensor section 1152b. The second sensor section 1152b is capable of measuring soil chemistry at a depth B in the soil structure. The sensor part 1150 or 1148 of the second sensor section 1152b is coupled to the tube part 1108 of the tip sensor section 1154. The tip sensor section 1154 is capable of measuring soil chemistry at a depth C in the soil structure. The tapered tip 1122 of the tip sensor section 1154 forms the tip of the probe 1100. The tapered tip 1122 is preferably a sharp metal tip that helps the insertion of probe 1100 into a soil structure, and minimizes damage to the tip of probe 1100 and to the sensors inside the probe.
[0114] As shown in Figure 11a, a soil chemistry sensor 1124 is located inside each sensor part in a substantially horizontal / lateral orientation. Turning now to Figures 11b and 11c, these represent in more detail two different arrangements for horizontal soil chemistry sensors 1124. Probe 1100 can be formed using one or the other or each of the sensor parts 1148, 1150 described below.
[0115] Figure 11b shows the sensor part 1148, which comprises a porous membrane 1136 and a soil chemistry sensor 1124. The sensor part 1148 contains a reservoir of liquid (water) 1138. Electrolytes / ions in the soil immediately on the side from outside membrane 1136, they flow into reservoir 1138 through porous membrane 1136, enabling the soil chemistry sensor 1124 to measure soil chemistry through the reservoir instead of through direct contact with the soil. The sensing portion 1148 is tightly sealed to prevent liquid in the reservoir 1138 from leaking into an adjacent sensing section. Wiring 1106 from each ion selective electrode 1126 and reference electrode 1128 leaves each sensor part 1148 through a tight seal (not shown) to prevent leakage. In embodiments, the sensing part 1148 (and 1150) may not extend across the full width or cross section of probe 1100, such that the wiring 1106 of each electrode may extend upward through probe 1100 in a non- occupied by the sensing parts.
[0116] Figure 11c shows the sensor part 1150 in more detail, which comprises a 'key-shaped' membrane 1142 on reference electrode 1128 and a 'key-shaped membrane' 1144 on ion selective electrode 1126. Here , electrodes 1128 and 1126 may not be formed using pipette tips as previously described. Membranes 1142 and 1144 are level or substantially level with the surface of probe 1100. In this arrangement, the sensor part 1150 does not require a liquid reservoir, as the electrode membranes are in direct contact with the external environment (for example, soil or water). Therefore, the detection membranes 1142 and 1144 advantageously detect concentrations of chemicals in the soil adjacent to each membrane, rather than merely the chemicals that flow into a liquid reservoir. This may be particularly preferable when probe 1100 is used to measure the chemistry of soil water, which flows slowly through a soil structure. The modality shown in Figure 11b may be preferred when measuring concentrations of chemicals in water (for example, hydroponic growth media or rivers). As before, the sensor part 1150 may not extend across the full width or cross-section of probe 1100, such that wiring 1106 connecting the electrodes to a data logger (not shown) may extend upward through the probe 1100 in a space not occupied by the sensor parts. On-site Soil Chemistry Measurement at Different Depths With 'Key Type' Sensors
[0117] The probes described above use soil chemistry sensors in a vertical arrangement or in a lateral arrangement inside the probe. In an additional alternative probe modality, the ground sensors are similar to a key along a probe length. Figure 12a illustrates a probe 1200 comprising multiple 'key-type' soil chemistry sensors for measuring soil chemistry at multiple depths within a soil structure.
[0118] The probe 1200 comprises a part of tube 1204 and multiple sensors 'of the type of key' 1206 arranged along the length of the probe. Membranes of each 1206 sensor are flush or substantially flush with the outer surface of probe 1200. The 1206 sensors are positioned at fixed points along the probe, such that the first sensor measures soil chemistry at a depth A below the surface of soil, the second sensor measures soil chemistry at a depth B and so on. Thus, the probe is configured to measure soil chemistry at these depths set below the soil surface. Probes of different lengths and / or different sensor positions can be manufactured to take measurements at alternative depths. At the lower end of probe 1200 there is a tapered tip part 1212. The tapered tip 1212 is preferably a sharp metal tip that assists in inserting probe 1200 into a floor structure, and minimizes damage to probe end 1200 and sensors in the inside. The upper end of probe 1200 is sealed by a plastic cap 1202 to prevent water / soil water from entering probe 1200 from the top.
[0119] As shown in Figure 12a and in the enlarged view of Figure 12b, sensor 1206 is a double key type sensor, since each membrane is provided by a separate key type sensor. Both the reference membrane 1208 and the ion selective membrane 1210 have a key shape. Membranes 1208 and 1210 are positioned side by side in such a way that they are as close together as possible and measure soil chemistry at substantially the same position in the soil structure. Although in Figure 12a the membranes 1208 and 1210 are positioned one above the other, in other embodiments they can be positioned side by side. Each membrane 1208, 1210 is coupled to a conductive contact element (for example, silver) 1216 by means of a conductive gel 1214. Each contact 1216 is coupled to wires 1220 by means of a welding point 1218. Wires 1220 can be enclosed by an insulating material 1222 for connection to a data logger (not shown).
[0120] Turning now to Figures 12c and 12d, these illustrate an alternative array of probe 1200, also comprising multiple 'key type' soil chemistry sensors for measuring soil chemistry at multiple depths within a soil structure. Here, probe 1200 comprises a tube part 1204 and multiple sensors of the single key type 1224. A sensor of the single key type 1224 provides both reference and ion selective membranes. Both membranes are fused to a single-key type sensor. As shown in more detail in Figure 12d, sensor 1224 comprises two parts, where one part provides a reference membrane 1226 and the second part provides an ion selective membrane 1228. Although the two parts are shown one above the other, in in other embodiments, they can be positioned side by side (that is, the key sensor 1224 can be rotated by 90 °). Each membrane 1226, 1228 is coupled to a conductive contact element (for example, silver) 1216 by means of a conductive gel 1214. Each contact 1216 is coupled to wires 1220 by means of a welding point 1218. Wires 1220 can be enclosed by an insulating material 1222 for connection to a data logger (not shown).
[0121] A single-key or double-key type sensor is 'connected' separably to an opening provided along the length of tube part 1204. Advantageously, this enables the sensors to be separated and replaced if they are failing or if a different ion has to be measured. In addition, each sensor membrane of the double button type can be removed separately.
[0122] No doubt many other effective alternatives will occur for those skilled in the art. For example, a sensor modality can be used not on-site within the soil, but to measure nitrate levels in the soil over the site. In this case, a core sample can be excavated and shaken with water to obtain a measurement immediately. Similarly, a sensor modality can be used to measure nitrate levels in leaves (again agitated with water), which has value in research and creation as well as in farm harvesting tests.
[0123] It will be understood that the invention is not limited to the described modalities and covers apparent modifications for those skilled in the art and being within the spirit and scope of the attached claims.

权利要求:
Claims (15)
[0001]
1. Soil chemistry sensor for detecting soil chemistry on site, the sensor characterized by the fact that it comprises a probe incorporating a first ion selective electrode and a second reference electrode, in which said ion selective electrode comprises a first electrode having a porous ion selective plug towards a distal end of the first electrode, said first electrode including a first conductor in a first electrolyte, wherein said reference electrode comprises a second electrode having a porous electrode plug of reference towards a distal end of the second electrode, said second electrode including a second conductor in a second electrolyte, wherein said ion selective porous plug and said reference electrode porous plug are within a distance of 10 mm each other, and each of said porous reference electrode plug and said ion selective plug comprises a poly mere molded with solvent.
[0002]
2. Soil chemistry sensor, according to claim 1, characterized by the fact that each of said reference electrode porous buffer and said ion selective porous buffer comprises the same said polymer; and / or wherein said polymer is PVC.
[0003]
3. Soil chemistry sensor according to claim 1 or 2, characterized by the fact that said polymer of said porous reference electrode plug includes one or more additives to decrease an electrical resistance of said porous electrode plug of reference.
[0004]
4. Soil chemistry sensor, according to any of the preceding claims, characterized by the fact that said first and second electrodes are sealed within a waterproof wrap, in particular in which said waterproof wrap comprises cold contraction tube.
[0005]
5. Soil chemistry sensor, according to any one of the preceding claims, characterized by the fact that said second reference electrode comprises a double junction electrode including a second electrode chamber connecting with said second electrode by means of a second porous plug, said second internal electrode chamber containing said second conductor in said second electrolyte, in particular said second porous plug comprising said polymer.
[0006]
6. Soil chemistry sensor, according to any of the preceding claims, characterized by the fact that each of said first electrode housing and said second electrode housing comprises plastic; and / or wherein said ion-selective porous buffer is a selective nitrate buffer.
[0007]
7. Soil chemistry sensor, according to any one of the preceding claims, characterized by the fact that it still comprises a fixation device around said distal ends of said first and second electrodes to inhibit said distal ends from separating, in particularly wherein said ion selective porous plug and said reference electrode porous plug are within a distance of 10 mm, 5 mm, more preferably 3 mm, much more preferable 2 mm from each other.
[0008]
8. Soil chemistry sensor, according to any of the preceding claims, characterized by the fact that it still comprises said moisture detection device.
[0009]
9. Soil chemistry sensor, according to any one of the preceding claims, characterized by the fact that it also comprises a voltage sensor coupled to said first and second conductors, and a wireless network transmitter coupled to said voltage sensor for enable wireless collection of soil chemistry data from said soil chemistry sensor.
[0010]
10. Plurality of soil chemistry sensors, each sensor as defined in any one of the preceding claims, characterized by the fact that it is coupled to one or more voltage sensors, in which said one or more voltage sensors are coupled to a or both of i) a shared data logger, and ii) a shared wireless network transmitter to enable wireless collection of soil chemistry data from said soil chemistry sensors.
[0011]
11. Method of collecting soil chemistry data from the soil at the site, the method characterized by the fact that it comprises inserting the soil chemistry sensor, as defined in any one of claims 1 to 10, in the soil to be measured in local.
[0012]
12. Method, according to claim 11, characterized by the fact that it still comprises one or both of: i) measuring one or both of a mixture content of said soil and an ionic force of water in said soil, using said soil chemistry sensor, and compensating for a signal from said soil chemistry sensor responsive to a result of said measurement; and ii) providing a plurality of said soil chemistry sensors at different depths within said soil.
[0013]
13. Use of a soil chemistry sensor, as defined in any of claims 1 to 9, characterized by the fact that it is to determine chemistry data from a sample of plant material or to identify a soil chemistry depletion zone around a plant root.
[0014]
14. Use of a plurality of soil chemistry sensors, as defined in any of claims 1 to 9, characterized by the fact that it is to determine soil chemistry data at a plurality of depths in a soil sample.
[0015]
15. Method of manufacturing a soil chemistry sensor for detecting soil chemistry on site, characterized by the fact that the sensor comprises a probe incorporating a first ion-selective electrode and a second reference electrode, in which said selective electrode The ion electrode comprises a first electrode having a porous ion selective plug towards a distal end of the first electrode, said first electrode including a first conductor in a first electrolyte, wherein said reference electrode comprises a second electrode having a plug porous reference electrode towards a distal end of the second electrode, said second electrode including a second conductor in a second electrolyte, wherein said ion selective porous plug and said porous reference electrode plug are within one 10 mm from each other, and each of said porous reference electrode plug and said selective plug of ions comprise a polymer; the method comprising making said porous electrode plugs by solvent molded polymer.

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法律状态:
2018-11-21| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2019-11-05| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2020-04-22| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2020-10-27| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 20/12/2013, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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GB1223167.6|2012-12-21|

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GB1223167.6A|GB2509127B|2012-12-21|2012-12-21|Soil chemistry sensor|

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PCT/GB2013/053377|WO2014096844A1|2012-12-21|2013-12-20|Soil chemistry sensor|

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