A computer-implemented method for providing a site-specific variable fertilizer recommendation for a crop at a given point in time, the method performed by executing a computer program on a processor and comprising steps of:
- a. determining at least one agricultural field comprising at least one crop;
- b. scheduling a fertilization application for the at least one agricultural field for a scheduled application date;
- c. remotely determining a crop nutrient status of the at least one agricultural field, wherein remotely determining a crop nutrient status of the at least one agricultural field comprises:
- i. receiving remote data, via a communication unit, the remote data comprising image data of the at least one agricultural field and a time stamp indicative of when the image data was taken, the remote data provided by at least one remote sensing device including at least one imaging satellite or imaging aerial vehicle;
- ii. generating, by executing the computer program on the processor, at least one vegetation index (SXi,jtm) indicative of a crop nutrient status based on the image data;
- iii. determining, by executing the computer program on the processor, a crop nutrient status based on the at least one vegetation index;
- d. adjusting, by executing the computer program on the processor, the crop nutrient status based on a time difference between the time stamp of the image data and the scheduled fertilizer application, wherein adjusting the crop nutrient status comprises:
- i. determining, by executing the computer program on the processor, a dry matter value of the at least one crop at the time of the received image data used for generating the at least one vegetation index;
- ii. simulating, by executing the computer program on the processor, an evolution of the dry matter value of the at least one crop in the at least one agricultural field between the time of the image data and the scheduled fertilizer application;
- iii. wherein simulating the evolution of the dry matter value further comprises receiving weather data via the communication unit and iteratively updating the crop's dry matter based on the weather data between the time stamp of the received image data and the scheduled application date;
- and
- iv. adjusting, by executing the computer program on the processor, the crop nutrient status based on the simulation of the crop's dry matter;
- e. determining, by executing the computer program on the processor, a variable fertilizer recommendation for the at least one agricultural field based on the adjusted crop nutrient status;
- f. generating, by executing the computer program on the processor, a machine-readable prescription map based on the variable fertilizer recommendation;
- and
- g. controlling an agricultural apparatus using the machine-readable prescription map to perform the site-specific variable fertilizer application,
- wherein receiving the weather data of the at least one agricultural field further comprises receiving daily temperature and solar irradiance values, and wherein iteratively updating the crop's dry matter value further comprises updating the dry matter value by a generated value proportional to a daily absorbed photosynthetic radiation, calibrated by a temperature efficiency factor,
- wherein iteratively updating the crop's dry matter comprises generating a daily dry matter value (DMi+1) based on the dry matter value from a previous day (DMi) and a development factor as follows:
- DM
- i
- +
- 1
- =
- DM
- i
- +
- k
- *
- h
-
- (
- DM
- i
- )
- *
- E
- i
- *
- f
- T
- (
- T
- i
- )
- wherein the iteration is carried out for i=1, . . . , n;
- wherein n represents a number of days between the date of the image data and the fertilizer application date and wherein k represents a constant which may take different values based on crop data, wherein function h is proportional to a daily fraction of absorbed photosynthetic radiation;
- Ei is a daily solar irradiance, and function fT is a temperature calibrated function which represents a temperature efficiency factor as a function of the daily temperature.