Hello Mayo,

to your questions in your text below:
Quote Originally Posted by Mayo View Post
I'm getting this straight in my head now.
Welcome in the club. I'm also learning.
Ammonium NH4+ is only toxic to higher plants in high concentrations. Being closely bound to clay/humus leaching would be far less likely than with Nitrates NO3-.
It is toxic in high, localised, concentration to all life. Almost could say: "Who cares of 5% of the soil profile being "sterilised" if 95% iof the profile are unefected by the affect a N as nitrate dose can give. The potential of more life, abundance of species, beneficial for the whole system, is there to outnumber the "loses" of 5% "sterelised" soil.
Can accept that localised poisoning of the soil is probably preferable to sprinkling it across the whole field.
In relation to DD/soil health, this system will surely work far more effectively, in a 'busier' soil (perhaps under DD for several years), with a great amount of soil life around, and so the effect and benefit of the plant is increased?
Yes. We are observing very interesting observations, which are growing. The list starts with: healthier plants, better quality, less weather stress, up to N saving. As longer we are doing it consequently as better it get's.
However, I guess there is also an alternative mechanism, by which more bugs mean faster NH4 breakdown to NO3 and thus the plant has a belt and braces approach and can take up either as and when?
Yes and no. Basically the plant prefers NH4, as it is much more energy efficient for the plant. So it is the "trick" to get the right relation of concentration on a spot or in a line with the size of surface area on the "N-depot" where the bugs can work on. In reality you don't need any bugs as the plant can feed itself straight with the NH4.
I read elsewhere that sulphur, being a key ingredient in some amino acids will definitely affect nitrate use in plants.
please read the reference once more. S is not only a key element in it because it's connection in Ammino Acid's but also it is a key element in the stabilising of the "N-depot".