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Chesley, Ontario | Jake;
There is a big difference between how the annual (grain) legumes behave, and the perennial (forage) legumes. The annual legumes pretty much stop sending carbohydrates down to the roots once grain fill starts, which cuts off the food supply for the nodules. From there on, everything is moving up in the plant towards the sink in the filling seeds, including the N in the nodules. The carcasses are there, but there isn't much N left in them by harvest. There have been a number of different studies showing lower levels of post-harvest soil N following soybeans than following corn. In the perennial legumes, the food supply to the nodules keeps going, so there is significant N left in the soil after clover or alfalfa. | |
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Soybean tillage
