Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
  • G01N21/3563—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing solids; Preparation of samples therefor
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01C—PLANTING; SOWING; FERTILISING
  • A01C21/00—Methods of fertilising, sowing or planting
  • A01C21/007—Determining fertilization requirements
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01M—CATCHING, TRAPPING OR SCARING OF ANIMALS; APPARATUS FOR THE DESTRUCTION OF NOXIOUS ANIMALS OR NOXIOUS PLANTS
  • A01M7/00—Special adaptations or arrangements of liquid-spraying apparatus for purposes covered by this subclass
  • A01M7/0089—Regulating or controlling systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/02—Food
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
  • G01N2021/3155—Measuring in two spectral ranges, e.g. UV and visible
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
  • G01N2021/396—Type of laser source
  • G01N2021/399—Diode laser
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
  • G01N21/359—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using near infrared light
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
  • G01N33/483—Physical analysis of biological material

Definitions

• the present invention relates to the field of crop yield management and improvement.
• a method whereby the crop leaf area and the chlorophyll content and/or the biomass of the crop is measured simultaneously in real time as a means of optimising the application to the crop of plant yield improving agents such as fertilisers, herbicides, pesticides and fungicides.
• the invention provides a novel dual sensor device that is capable of measuring the leaf area and the chlorophyll/biomass content.
• plant yield improving agents e.g. fertilisers such as N-fertilisers
• fertilisers such as N-fertilisers
• the levels of fertilisers and other auxiliary chemical agents are adequate at any given stage of the growth cycle.
• N-fertiliser is based solely on measurements of biomass and/or chlorophyll content of the crop as such without correcting for spatial variations in leaf area per unit area, some areas will receive less than the required amount and other areas will re- ceive an excess amount relative to the actual local requirement.
• the Hydro N-sensor and other published remote sensing based single instrument systems are not capable of measuring leaf area independent of chlorophyll content and/or biomass. Because of correlation between e.g. estimates of canopy leaf area and chlorophyll content, these systems are not capable of accurately estimating mean leaf chlorophyll content and the crop nitrogen status.
• the control of fertiliser application and optionally, application of other growth yield improving agents offered by such systems is merely related to the biomass/chlorophyll content of the plant leaves at any given plot of the field, but not to the leaf area index (LAI) of the crop growing in that particular plot, which inevitably will lead to the application of less than optimal amounts of fertiliser or any other agent being applied at plots with a high LAI and conversely, to the application of excesses of agents at plots with a smaller LAI.
• LAI leaf area index
• Toivonen et al. describes a portable device for determination of chlorophyll in plant by measuring fluorescence.
• the present inventor has now discovered that the application of fertilisers and any other crop yield optimising agents such as fungicides, herbicides or pesticides can be optimised substantially be combining real time measurements of plant chlorophyll/biomass content with simultaneous measurements of the plant leaf area, height and density.
• the type of measurements used depends on the agent (e.g. fertiliser or fungicide) to be applied.
• the application of fungicides and other surface active agents can be optimised by varying the rate according to especially leaf area but also height an density.
• the present invention provides in a first aspect a method of controlling the application of fertilisers, fungicides, herbicides or pesticides to a plant crop, the method comprising simultaneous real time measurements of chlorophyll and/or biomass contents by determining the a Vegetation Index (VI) such as Reflectance Vegetation Index (RVI), Red Edge Inflection Point (REIP) or an equivalent measure of chlorophyll and/or biomass content, and crop leaf area by determining the Leaf Area Index (LAI) or an equivalent measure of crop leaf area, providing said measurement data to a data processing unit which calculates an VI/LAI ration, such as an RVI/LAI ratio, an REIP/LAI ratio or an equivalent ratio as an indication of the chlorophyll content per unit leaf area, said data processing unit is operably connected with a control unit regulating the application of fertilisers, fungicides, herbicides or pesticides to the plant crop.
• VI Vegetation Index
• RVI Reflectance Vegetation Index
• REIP Red Edge Inflection Point
• the invention pertains to a dual sensing device for real time controlling the application of a crop yield improving agent, the device comprising (i) means for determining a VI such as RVI data, REIP data or data for an equivalent measure of chlorophyll and/or biomass content, (ii) means for determining LAI data or data for an equivalent measure of crop leaf area, data processing means to combine the VI and LAI data or data for equivalent measures to an VI/LAI ratio or an equivalent ratio and means for transmitting VI/LAI ratio data or equivalent ratio data to a device controlling the application of the crop yield improving agent.
• a VI such as RVI data, REIP data or data for an equivalent measure of chlorophyll and/or biomass content
• means for determining LAI data or data for an equivalent measure of crop leaf area data processing means to combine the VI and LAI data or data for equivalent measures to an VI/LAI ratio or an equivalent ratio and means for transmitting VI/LAI ratio data or equivalent ratio data to a device controlling the application of the crop yield improving agent.
• a primary objective of the present invention is to provide the means for optimising agricultural crop yield by designing a method of improved control of the application of crop yield improving agents, in particular fertilisers such as N-fertilisers, but also other improv- ing agents such as fungicides.
• This is achieved by providing a method of controlling in real time the application of such agents to a plant crop by combining measurements of chlorophyll and/or biomass contents in the crops to which the agent is to be applied by determining a Vegetation Index (VI) such as the Reflectance Vegetation Index (RVI), the Red Edge Inflection Point (REIP) or equivalent measurements of the biomass/chlorophyll content and crop leaf area by determining a leaf area index (LAI) or a corresponding measure of the plant leaf area.
• the method of the invention is applicable to both monocotyledonous and dicotyledonous plant crops.
• the ratio gives an indication of the chlorophyll content at the leaf level of each plant. It is thus possible to distinguish between a situation where a low level of chlorophyll and/or biomass content in a certain part of a field is due to the plants in this given area of the field is nutritionally deficient or are due to the plants in the given area is grown with a high distance between the individual plants.
• a critical parameter in determining the ratio between the chlorophyll and/or biomass contents and the crop leaf area is that the crop leaf area is determined accurately and within the same area wherein the chlorophyll and/or biomass content is being measured.
• the RVI is typically measured by means of a sensing device that is capable of measuring the reflectance (p) of the crop in the visible light spectrum, such as the red light spectrum and in the near infrared (NIR) spectrum and combining the measurement values into the spectral index, RVI. It has been found that RVI measurements are closely related to the biomass and chlorophyll content of crops. RVI may be influenced by the altitude of the sun which implies that RVI measurements can only be made with high precision around noon.
• REIP Red Edge Position
• CCD canopy chlorophyll density
• the REIP and SAVI2 is examples of "an equivalent measure of plant biomass/chlorophyll content”.
• the formulas of three Vis are given in Table 1.
• o, c_, c 2 , c 3 , c 4 , c s and c 6 are coefficients associated with a polynomial curve fit over the vegetation red edge region (670 - 780 nm).
• a canopy reflectance model (ProSAIL (Jacquemoud et al., 2000)) can be employed to simulate spectral reflectance with 10 nm band spacing of a range of similar canopies.
• the selected range of model input parameters represent a wheat crop.
• the mathematical form of the ProSAIL model is
• p is reflectance at wavelength ⁇
• ⁇ s (°) and y/ s (°) represent the solar zenith and azimuth angles
• ⁇ v ⁇ °) and ⁇ v ⁇ °) represent the view zenith and azimuth angles
• MTA(°) is the mean leaf tilt angle
• ⁇ /(-) is a parameter describing the leaf mesophyll structure
• C 3 ⁇ ( ⁇ g/cm 2 )) is the leaf chlorophyll concentration
• Cw(cm) is the leaf water depth
• C DM (g/cm 2 ) is the leaf dry matter content
• s is the Kuusk hot spot size parameter (Kuusk, 1991)
• p s is the soil background reflectance at wavelength ⁇ .
• the ProSAIL model builds on the following assumptions regarding canopy morphology: • the canopy is horizontal, homogenous and infinitely extended
• the canopy consist of small green flat leaves and is characterised by a uniform leaf azimuth distribution.
• a presently preferred method of measuring the crop leaf area index is by applying a scan- ning laser instrument that, when applied to the crop field area and moved herein, is capable of continuously recording, at a high precision level, the leaf area of the crop, the reflection of the plant organs and the height and density (canopy cover fraction) of the crop plants.
• the leaf area index (LAI) is calculated on the basis of measurements of canopy gap fractions by means of a model for light penetration in a crop and numerical inversion of the model. Other means of obtaining LAI data are conceivable such as e.g. ultrasonic measurements, and such means are within the scope of the present invention.
• the crop leaf area, height and density is being determined from a number of scan lines perpendicular to the direction of travelling of the vehicle carrying the instrument, i.e. the scan is crosswise of the plant rows.
• Measurement of standard parameters such as LAI, height and density is important for the regulation of the application of surface active compounds such as fungicides and in part also pesticides.
• RVI and corresponding values have been used previously in several experiments aiming at describing the development of a variety of crops and the harvest yield hereof under varying N-applications. These measurements have been performed both as manual and position determined mobile measurements.
• the spectral index is, as mentioned above, closely related to green biomass of a crop and the amount of chlorophyll per unit area of ground. Accordingly, the RVI/LAI ratio is a measure of the chlorophyll content per unit leaf area, which in turn is a measure of the nitrogen content of the leaves and the nitrogen requirement of the crop.
• the REIP/LAI ratio is a measure of the chlorophyll content per unit leaf area, which in turn is a measure of the nitrogen content of the leaves and the nitrogen requirement of the crop.
• C gb the leaf chlorophyll concentration in ⁇ g/cm 2
• C gb the leaf chlorophyll concentration in ⁇ g/cm 2
• the crop nitrogen status is achieved by the direct measurement of canopy structural parameters (leaf area, height and density), and the herein described system thus allows a more accurate application of e.g. N-fertilisers and/or plant protection agents as compared to previously described systems which are not capable of measuring leaf area independently of chlorophyll content and/or biomass.
• the data are transmitted to a data processing unit operably linked to measuring device, which unit calculates an RVI/LAI ratio or an equivalent ratio as an indication of the chlorophyll content per unit leaf area.
• the data processing unit is in turn operably connected with a control unit regulating the application of fertilisers, fungicides, herbicides or pesticides to the plant crop being measured.
• a dual sensing device comprising (i) means for determining RVI, REIP or the equivalent thereof and (ii) means for determining LAI or the equivalent thereof which conveniently is mounted on a tractor or any other vehicle carrying a device for application of a fertiliser, a fungicide, a herbicide or a pesticide in such a manner that the dual sensing device is operably linked to the sensing device.
• the LAI is conveniently measured by measuring canopy gap fractions by means of a laser diode such as an IR laser diode.
• a laser diode such as an IR laser diode.
• Presently preferred LAI measuring parameters for the laser diode include: a small measuring area (spot), e.g. less than 1 mm including less than 0.75 mm, less than 0.50 mm or less than 0.25 mm, measurement of the strength of the reflected signal and a relatively high measuring frequency such as at least 25 kHz, at least 50 kHz, at least 75 kHz or at least 100 kHz.
• the laser diode is connected with a scanning unit and preferably the entire LAI measuring device is adapted to mobile measurements.
• RVI or an equivalent measure of the biomass/chlorophyll content is determined by means of combining measurement data for crop reflectance of visible light and near infrared light.
• the inverse re- flectance of visible light is e.g. carried out within the red light spectrum such as at about 650 nm.
• Any type of spectral analysis equipment that is capable of providing spectral data that are correlated to chlorophyll and/or biomass content of growing plants can be used in the present method. E.g. may such equipment which also functions appropriately in vary- ing daylight intensities and solar altitudes and/or in artificial light be particularly useful.
• a dual sensing device for real time control of the application of a crop yield improving agent.
• a device comprises means for determining RVI data or equivalent data and means for determining LAI data or equivalent data.
• the device further comprises appropriate data processing means including software programmes to convert the signals received from the sensors to digital data, data processing means for combining the obtained RVI and LAI data or the equivalents thereof into an RVI/LAI ratio or equivalent ratio and means for interfacing such ratio data with a device controlling the application of the crop yield improving agent.
• a controlling device should include adequate mechanical means permitting the adjustment of the flow of the fertiliser or other yield improving agent to the crop or the soil.
• a dual sensing device for real time control of the application of a crop yield improving agent.
• a device comprises means for determining REIP data or equivalent data and means for determining LAI data or equivalent data.
• the device further comprises appropriate data processing means including software programmes to convert the signals received from the sensors to digital data, data processing means for combining the obtained REIP and LAI data or the equivalents thereof into an REIP/LAI ratio or equivalent ratio and means for interfacing such ratio data with a device controlling the application of the crop yield improving agent.
• a controlling device should include adequate mechanical means permitting the adjustment of the flow of the fertiliser or other yield improving agent to the crop or the soil.
• a 4 channel portable multispectral radiometer developed at Research Centre Foulum (Thomsen et al., 2002) may be employed. This system is capable of calculating both REIP and RVI.
• the means for measuring LAI is adapted to measure canopy gap fractions by means of a laser diode e.g. having functional characteristics as it is described hereinbefore.
• a significant aspect of the sensing device of the invention is that it can be used for real time simultaneous field monitoring of RVI and LAI data, REIP and LAI data, RVI and REIP and LAI data or equivalent data. It will be appreciated that such monitoring may be carried out by using portable device units e.g. connected wirelessly to agent application control devices mounted on a tractor or a similar vehicle carrying the means for applying the fertiliser or other yield improving agent.
• the dual sensing device is mounted directly on the tractor or other vehicle and is therefore provided with means for mounting it on a tractor or vehicle or on another device or part mounted on the tractor or vehicle.
• the means for measuring RVI, REIP and LAI, respectively or measures equivalent with such indice.s can be separate means used or mounted separately, i.e. used or mounted as separate units. However, it may be preferred that said measuring means are located within the same housing, i.e. as a single unit comprising the two sensing means. In both cases, it is important that the sensing devices are within single housing or separate housings that are made of a material having a strength and form that provide sufficient protection of the sensors towards mechanical and physical "hardship".
• Fig. 1 it is illustrated how the RVI/LAI index measure- ments provided by the method of the invention can be applied for controlling the application of nitrogen to crops. Assuming that a first nitrogen application is carried out at an early stage of the growth season, e.g. in March/April and a second application in May and further that the soil quality and the expected yield requires a "standard" nitrogen application of 160 kg/ha.
• the point at the lowest RVI value represents a point with a relatively low plant density and a low amount of biomass and a correspondingly better nitrogen supply and higher chlorophyll content in the leaves.
• the point at the lowest RVI value represents a point with a relatively low plant density and a low amount of biomass and a correspondingly better nitrogen supply and higher chlorophyll content in the leaves.
• the diagram As it can also be derived from the diagram, it will at a uniform plant density secure an optimal nitrogen application and uniform crop yield all over the field.
• the diagram In fields with a substantial variation in growth conditions e.g. related to differences in soil structure, the diagram is used in combination with a digital map showing the variation in the "standard" nitrogen application. The application of nitrogen in the individual points is calculated as the interpolated difference between the measuring point and the standard nitrogen application.
• PROSPECT A Model of Leaf Optical Properties Spectra. Remote Sensing of Environment. 34:75-91.

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• 2002
  • 2002-07-24 EP EP02754554A patent/EP1419385A1/de not_active Withdrawn
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