The rise of the dollar means that the dollar has become valuable. Because the intrinsic value of soybeans remains unchanged, and American futures are priced in dollars, each dollar can buy more soybeans, and relatively speaking, futures will fall in price. On the contrary, the dollar fell, and each dollar can only buy less futures, so futures rose.

But the most essential thing that determines the futures price is the relationship between supply and demand. Supply and demand decide everything! There are many factors that affect the relationship between supply and demand of futures prices, including macroeconomic factors, interest rate levels, irresistible factors (disasters) and so on.