US 11,985,925 B2
Method of determination of water stress in a one or more plants in a crop located in the region of a soil moisture sensor array and knowledge of ETo
Peter Buss, South Australia (AU)
Assigned to Sentek Pty Ltd., South Australia (AU)
Filed by Sentek Pty Ltd, South Australia (AU)
Filed on Apr. 25, 2022, as Appl. No. 17/728,017.
Application 17/728,017 is a continuation in part of application No. 16/639,853, granted, now 11,310,970, previously published as PCT/AU2018/000145, filed on Aug. 22, 2018.
Claims priority of application No. 2017903385 (AU), filed on Aug. 22, 2017.
Prior Publication US 2022/0248617 A1, Aug. 11, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. A01G 25/16 (2006.01)
CPC A01G 25/167 (2013.01) [G05B 2219/2625 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method for indicating the onset of water stress prior to or on a stress determination day d in one or more plants located in soil the roots of which are within the measurement zone of a vertical array of soil moisture sensors located in the soil wherein the soil moisture sensors are part of an array to extend from near the soil surface to at least below the root zone of the plants, the sensors adapted to provide data representative of the total water volume in millimeters of moisture per 100 millimeters of soil at multiple depths of the soil, at multiple times during a 24 hour period over a predetermined number of consecutive 24 hour periods before day d, and data representative of the value of evapotranspiration in millimeters of moisture of each day of the predetermined number of consecutive 24 hour periods and day d in the same region as the one or more plants is made available, and a water in soil detector arrangement in the region of the soil moisture sensor making available data representative of the event of a water into soil event within one or more of the consecutive 24 hour periods, the steps of the method comprising:
a) determine from data representative of the total water volume of the soil of the daily crop water usage being the total water volume in millimeters of moisture per 100 millimeters of soil during a 24 hour period, the rate of soil moisture depletion during the plant moisture uptake period within each respective 24 hour period within the predetermined number of consecutive 24 hour periods adjusted for drainage, but only if there are more than two 24 hour periods of measurable daily crop water usage within the predetermined number of consecutive day 24 hour periods or there was no water in soil event on day d;
b) calculate a line of best fit of the daily crop water usage and recorded evapotranspiration for the predetermined number of consecutive 24 hour periods;
c) calculate the difference of each daily crop water usage from the line of best fit;
d) determine the statistical standard deviation of the differences of each daily crop water usage value from the line of best fit;
e) determine a predicted crop water usage for day d using the evapotranspiration for day d and the line-of-best fit;
f) determine whether the difference between the daily crop water usage for day d and the predicted crop water usage for day d, and if the difference is equal to or more than the value V, where the value V is an amount of deviation from the mean; and
g) indicate that a period of water stress of the one or more plants has been entered as of day d to thereby control elements of a crop management arrangement to irrigate or not to irrigate automatically with no human intervention.