1. Nitrogen Fertilization of Soybean

Nitrogen (N) requirement of soybean is high because of the high protein seed produced. One bushel of soybean requires over 3.5 pounds of N in the grain alone. Symbiotic Nz fixation supplies N for soybean, but Harper (1 974) reported that only 25 to 60% of the N in a marure soybean piant comes from N fixation while the other 40 to 75% comes from the soil. However. application of N fertilizer to soybean remains a very controversial issue because of mixed results of previous research....