Method and apparatus for the automatic regulation of the irrigation of plants

Abstract

A method for the automatic irrigation of plants, wherein the temporal progression of soil moisture is determined from measured soil moisture values, and the progression is used for the calculation of an optimized irrigation time duration, such that both water excess in the soil and soil drying are avoided as much as possible. Preferably, the time duration of irrigation is constantly evaluated and optimized using comparisons of measured values with prespecified moisture and dryness threshold values, and automatically adjusted to changing environmental conditions and/or plant requirements.

What is claimed is: 
     
         1 . A method for automatically controlling an irrigation duration, the method comprising
 calculating an irrigation duration by the aid of evaluation electronics and an application specific characteristic K;   obtaining a soil moisture value by measuring soil moisture using a sensor after a soil irrigation operation for the calculated irrigation duration has been conducted;   comparing the obtained soil moisture value with a target upper moisture limit value using the evaluation electronics and, in the event that the obtained soil moisture value deviates from the target upper moisture limit value, applying a correction to the application specific characteristic K to thereby alter an irrigation duration for a subsequent soil irrigation operation.   
     
     
         2 . The method according to  claim 1 , comprising
 obtaining a further soil moisture value by measuring soil moisture using the sensor before the subsequent soil irrigation operation is carried out; and   carrying out the subsequent soil irrigation operation only if the obtained further soil moisture value is lower than a dry limit value.   
     
     
         3 . The method according to  claim 2 , comprising inputting into the evaluation electronics the target upper moisture limit value and the dry limit value, wherein the target upper moisture limit value and the dry limit value are user-selected values. 
     
     
         4 . The method according to  claim 1 , wherein the applying the correction to the application specific characteristic K is accomplished
 by enlarging K to K+y with an absolute value y or to k*y with a factor y>1, in the event that the obtained soil moisture value reaches the target upper moisture limit value, thereby reducing the irrigation duration for the subsequent soil irrigation operation; and   by reducing K to K−x with an absolute value x or to k*x with a factor x<1, in the event that the obtained soil moisture value does not reach the target upper moisture limit value, thereby increasing the irrigation duration for the subsequent soil irrigation operation.   
     
     
         5 . The method according to  claim 1 , wherein an initial calibration measurement is conducted in which an initial application specific characteristic K used for calculating an irrigation duration for a next soil irrigation operation conducted after an initial soil irrigation operation is derived from a moisture value measured before the initial soil irrigation operation and a moisture value measured after the initial soil irrigation operation. 
     
     
         6 . The method according to  claim 1 , comprising inputting into the evaluation electronics a user-selected initial application specific characteristic K used for calculating an irrigation duration for a soil irrigation operation. 
     
     
         7 . The method according to  claim 1 , wherein the application specific characteristic K indicates by how much soil moisture changes when watering is performed for a specific duration and with a specific amount of water. 
     
     
         8 . An apparatus for automatically controlling plant irrigation operations using an associated irrigation device, the apparatus comprising
 at least one sensor configured to repeatedly measure soil moisture of soil irrigated by the irrigation device; and   an evaluation electronics configured to calculate an irrigation duration using an application specific characteristic K;   wherein the apparatus is configured to alter the irrigation duration of a subsequent irrigation operation by the aid of the evaluation electronics by applying a correction to a previous application specific characteristic K, if a soil moisture value obtained by the at least one sensor after an irrigation operation conducted for an irrigation duration calculated using the previous application specific characteristic K deviates from a target upper moisture value.   
     
     
         9 . An electronic controller for plant irrigation configured to be coordinated with a sensor for measuring soil moisture and with an irrigation device, the electronic controller comprising an evaluation electronics configured to calculate an irrigation duration with the aid of an application specific characteristic K, wherein the electronic controller is configured to alter the irrigation duration of a subsequent irrigation operation by the aid of the evaluation electronics by applying a correction to a previous application specific characteristic K, if a soil moisture value obtained by the sensor after an irrigation operation conducted for an irrigation duration calculated using the previous application specific characteristic K deviates from a target upper moisture value.