Based on the data of the survey and stationary monitoring of soil fertility, grain yields, weather, and fertilizer investigation of the recent 30 years in Yizheng, it was concluded that organic matter showed the pattern of a basin, a sign of balance between input and removal of organic matter in the farmland; available P rose at first, and declined and rose again; available K kept rising gradually, which is related to increase in P and K fertilizer application rate; available Zn showed a rising trend, but available B a reverse trend, which is closely related to readjustment of the planting structure. Over the past 30 years, the grain production in the region showed a curve that went up first, and then down and then up again. As variation of grain production is a reflection of the integration of a variety of influencing factors. Breakthroughs in the breeding technology often lead to big rises of yield, and weather influences crop yield of the season. Spatio-temporal variation of SNQI is the most closely related with variation of grain yield. The higher the ANQI value, the smaller the variation of grain yield between years, and the stronger the capability of resisting risks.