Soil elemental (mainly carbon) analysis is one of the critical features in agricultural practice. The based on different physical principal methods are began applied today instead of traditional chemical analysis. One of such methods is neutron-gamma analysis. This method has a lot of advantage before traditional methods. It is nondestructive in situ method, no sample preparation is needed, no time consuming and labor-intensive method. Method is based on the registration of gamma rays response of the main soil nuclei at its irradiation by fast neutron flux.

In this report we will discussed physical principles of this method, namely processes of penetration, moderation and interaction with soil elements of fast neutrons, gamma rays appearing and propagation in soil, creating the gamma spectra in gamma detector. Based on this discussion the ways of soil elemental content determination from gamma spectra will be represented. The comparison of received results of neutron-gamma analysis with data of chemical analysis demonstrate that this method can replace this last in agricultural practice.