Can we talk about soil nitrogen content results of various biomass mulches in an orchard system?

In this video, Helen Atthowe discusses soil fertility and plant health, and her experience and findings from decades of adding biomass to an abundant orchard system.

She covers soil nitrogen content, both soluble, high-nitrogen fertilizer and biological fertilizer.

This really challenges my long-held paradigms of soil fertility - I'm curious to hear others' thoughts about kjeldahl nitrogen and mulching with fruit-tree prunings, among other things.