Seasonal variations of soil fertility of fields under six forage grain multi-cropping patterns, respectively, were studied. Results showed that cultivation of forage crops, especially ryegrass and rye, in winter improved soil properties over cultivation of grain crops by lower soil pH and increasing contents of organic matter and available nutrients, which contributd to growth and possibly yield of the crop to follow. Soil pH increased but soil nutrients decreased with depth of the soil profile. After a cycle of the multi-cropping cultivation, soil pH increased slightly, but organic matter, total N, and available N decreased a bit, and available P and K dropped by a large margin.