MemberAugust 3, 2022 at 3:48 pm00565
biological nitrogen especially in the form of amino acids (or parts thereof) is always more efficient for the plant.
If I remember correctly nitrate gets taken up with the water stream (there is no choice for the plant), transported to the leaf, changed to ammonium (insect trouble says hello!), ammonium transported back down to the roots where it is converted to amino acids, which should have been taken up in the first place. It was around 15% of the photosynthetic capacity that is used for that process.
I know they have to do a lot of N budgeting in Germany and should have numbers for legumes there, I try to remember to look for some if you are interested. Quite busy time right now… But if you really have biology going in the soil, legumes are not the main focus of N fixation anymore.