Abstract: The effect of different fertilization systems on crop yield and soil phosphorous fertility was investigated in an 18-year field experiment in aquic-brown soils. The results indicate that crop yield significantly increases while the yield fluctuation decreased in treatments with phosphorous fertilizer compared to the control. In treatments without phosphorous fertilizer, there is a deficit in P budget and total and available P content decreases significantly. A strong linear correlation exists between P budget and available P fluctuation in treatments without phosphorous. In treatments with phosphorous, total P content increases significantly (from 0.02 to 0.04 g·kg^-1), while available P content also increases significantly (especially in the latter stages of the trial). N fertilizer application significantly increases maize grain yield, while P and K fertilizers have insignificant effect on maize yield increase. Conversely, while mean soybean yield is unaffected by N fertilizer application, P and K fertilizers affect mean soybean yield significantly.