Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Earth science
Reexamination Certificate
2001-03-28
2003-07-22
Lefkowitz, Edward (Department: 2862)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Earth science
C382S110000
Reexamination Certificate
active
06597991
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to sensing of irrigation status in crops.
BACKGROUND OF THE INVENTION
Water stress is known to be a major factor affecting crop yield. Further, it has long been known that crop canopy temperature is a good indicator of water stress in plants. For example, U.S. Pat. No. 4,998,826 to Wood et al., which discloses an “Agricultural Infrared Thermometer,” teaches (col. 1, lines 16-19) that “there is a narrow foliage temperature range, or a thermal kinetic window, within which the plant will achieve optimum yield and biomass production.”
A detailed overview of the state of the art in the use of thermal infrared measurements for monitoring and measuring plant health may be found in “Thermal Infrared Measurement as an Indicator of Plant Ecosystem Health” (520-670-6380 X 171, June 2000) by M. Susan Moran, published by USDA-ARS Southwest Watershed Research Center, Tucson, Ariz.
It is also known that the difference in temperature between well-watered and inadequately watered or stressed crop canopies depends on additional environmental factors such as total incident radiation, air temperature, relative humidity, and wind speed. In their article, “Canopy Temperature Characterization of Corn and Cotton Water Status,” Transactions of the ASAE, 43(4), 867, the contents of which are incorporated herein by reference, Wanjura and Upchurch review the progression of different measures of crop water stress and how they are determined or calculated and conclude that the crop water stress index (CWSI) is a superior measure of water stress, but that both theoretical and empirical forms of the CWSI (CWSI-T and CWSI-TC, respectively) require measurement or calculation of multiple environmental factors that make their application difficult and impractical.
U.S. Pat. Nos. 4,755,942 and 4,876,647 to Gardner et al. disclose portable apparatus to determine crop water stress by simultaneously measuring a number of environmental and plant physiological parameters including air temperature, relative humidity, and plant canopy temperature. However, measurements with the apparatus disclosed therein have the limitations of variations in the environmental parameters over time and across the extent of typical crop-growing areas and variations in plant canopy temperature measurements as a result of differences in the position and orientation of a hand-held sensor. As a result, the determination of crop water stress with the disclosed system is of limited reliability. Further, given the size and non-uniformity of typical crop-growing areas, measurements with the hand-held apparatus disclosed therein are totally impractical except for spot-checking, as opposed to systematic monitoring of plant water stress desired in commercial agriculture.
Another approach is that of Murray in U.S. Pat. No. 5,710,047, “Method for Monitoring Growth and Detection of Environmental Stress in Plants,” which relies on laboratory analysis of sample plant tissues. The method disclosed therein, while accurate, is also impractical for the systematic monitoring desired in commercial agriculture, especially if it is desired to control irrigation of crop-growing areas in a timely manner.
SUMMARY OF THE INVENTION
The present invention seeks to provide a method and system for evaluating the water stress status of growing crops in nearly real time employing remote monitoring of entire crop-growing areas, rather than sampling or spot checks, at sufficiently high resolution to recognize features in the crop-growing area, especially to distinguish between crop foliage and non-foliage features, and requiring minimal additional measurements of environmental parameters in the crop-growing area.
There is thus provided, in accordance with a preferred embodiment of the invention, a system for evaluating the water stress status of growing crops including:
a reference array near or within a selected crop-growing area for performing reference parameter measurements thereon;
one or more sensors, which may be portable, for measuring environmental parameters, such as global radiation, air temperature, relative humidity, and wind speed, in the vicinity of the crop-growing area and of the reference array;
a portable imaging sensor for measuring a preselected physical parameter, preferably surface temperature, on a pixel by pixel basis over a selected area, thereby producing a two-dimensional array of pixels corresponding to a thermal image of the crop-growing area and of the reference array;
a portable location sensor for detecting global location reference signals;
a mobile platform, preferably airborne, for supporting all the portable sensors, which maintains a predetermined altitude during measurement by the portable imaging sensor so that the thermal image of the crop-growing area and of the reference array is made up of measurement pixels of a predetermined size, preferably providing a measurement of the surface temperature of an area smaller than a meter squared;
data processing apparatus, which may also include one or more data storage devices, arranged in data receptive association with each other and with the sensors for receiving parameter measurements therefrom; and
a multiplicity of communications devices for transmitting the parameter measurements from the sensors and data storage devices to the data processing apparatus;
wherein the reference array allows measurement of reference parameters which, together with crop parameter measurements of growing crops, facilitates the data processing apparatus in determining the water stress status of the growing crops.
Additionally in accordance with a preferred embodiment of the invention, there is provided for use with the system for evaluating the water stress status of growing crops, a reference array near or within a selected crop-growing area for performing reference parameter measurements thereon, which includes a plurality of component reference surfaces, typically formed of fabric, in a predetermined arrangement, each of the component reference surfaces being a predetermined size and having predetermined radiometric and heat-convection properties; and wherein the component reference surfaces allow measurement of a plurality of reference parameters which, together with crop parameter measurements of growing crops, facilitates determination of the water stress status of the growing crops. The component reference surfaces include one or more first reference surfaces fabricated to produce preselected parameter measurements substantially equivalent to those taken on a potentially transpiring crop surface that is internally saturated and one or more second reference surfaces, which are substantially dry, shielded from thermal radiation coming from therebelow, and fabricated to have predetermined heat-convection properties. Accordingly, the first reference surface is configured to permit substantially free evaporation therefrom and includes wetting apparatus which continuously wets ARS
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first reference surface with water during preselected time intervals including when measurements are to be taken. Further in accordance with a preferred embodiment of the invention, there are two or more second reference surfaces, which are substantially dry and which include one or more uniformly light-colored surfaces and one or more uniformly dark-colored surfaces.
In accordance with an alternative embodiment of the invention, the reference array may further include one or more environmental sensors for measuring predetermined environmental parameters at its location. Additionally in accordance with an alternative embodiment of the invention, the reference array may also include temperature sensors for measuring the surface temperatures of the component reference surfaces of the reference array. The reference array may also include a clock device for producing time reference signals and wireless transmission apparatus for transmitting reference parameter measurements and time reference signals to the system so that the system can synchronize the reference param
Meron Moshe
Tsipris Joseph B.
Agrosense Ltd.
Gutierrez Anthony
Kayden James W.
Lefkowitz Edward
Thomas Kayden Horstemeyer & Risley
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