The invention relates to a system for evaluating in situ and continuously the crop-growing potential of an agricultural soil comprising a device for estimating hydrogen and nitrogen flows comprising water-monitoring devices, an earth-monitoring device and a hygrometric device, these being equipped with sensors intended to measure an amount of nitrates, temperature and pH, the temperature and moistness of a piece of ground, and the temperature of the air. Said monitoring devices each being connected by cables to dedicated acquisition boards. The estimating device furthermore comprises a microcontroller module controlling said acquisition boards and a communication module, said communication module sending measured results to a server. The estimating device is characterised in that the water-monitoring devices are placed respectively at 30 cm and 50 cm depth and the ground-monitoring device is placed at 50 cm depth, in that the monitoring devices are connected to the microcontroller module, which makes the requests for measurements and communicates the measured raw data to the server by means of the communication module, and in that the microcontroller module (5) activates the hygrometric device, at a regular and adjustable frequency, in order to measure the humidity of the air and to determine the periodicity of the requests for raw measurements of the various water- and earth-monitoring devices. The invention furthermore relates to a method implemented in the above estimating device.
