To address the shortcomings presented in the prior art, the present invention provides a system and method to provide improved irrigation management through the detection of fast neutrons. According to a preferred embodiment, the fast neutron detector of the present invention includes a 4-He based noble gas detector, a power source, a signal processing circuit, and a resistor in series with a preamplifier and a shaping amplifier to produce a processed signal. According to a further preferred embodiment, the present invention preferably further includes a signal channel analyzer and a pulse counter/rate meter. According to a further preferred embodiment, the present invention includes a controller which receives a count of detected fast neutrons and translates the detected number of fast neutrons into an irrigation map indicating the required levels of irrigation needed for selected areas of a given field based on the detected moisture levels.
