nitrogen fixing plants only fix nitrogen when they lack it
otherwise they will not fix nitrogen, or it will be very minimal
Straw taxes (takes) nitrogen from the soil as it decomposes! Do NOT USE it!
Pumpkins and squashes are greedy feeders,, they like horse manure,, added to the beds the autumn before cultivation... otherwise legume crops (peas and beans) grow in harmony with squashes/pumpkins,,, by fixing available nitrates directly into the soil.
Hope this helps
Also the legumes don't help until the next cycle when they break down
3. The roots of certain legume green manures can supply tons of free atmospheric nitrogen per acre to the topsoil after the cover crop plants are tilled, mowed down, or smothered. Rhizobacteria live inside the legume roots creating a unique relationship that actually converts atmospheric nitrogen into organic nitrogen for the legume to use. This extra nitrogen fixation built up by the rhizobacteria can not be beneficial to other plants near by, or future crops in the soil next season, until that legume is dead and recycled into the soil by the green manuring process. Compost can't fix nitrogen in the soil.