Do Hawthorns lock in nitrogen

As the hawthorn is in the Rose family it is one of the actinhorizal nitrogen fixing plants,my ceanothus produces it's own nitrogen,the Buddleia next to it is overcrowded with leaves,it flowers late too. Have you noticed anything like a bad effect on the blackberries,maybe not producing much fruit or are they fine & doing really well? This link explains a bit about actinhorizal plants.
"Actinorhizal plants have the ability to develop an endosymbiosis with the nitrogen-fixing soil actinomycete Frankia. The establishment of the symbiotic process results in the formation of root nodules in which Frankia provides fixed nitrogen to the host plant in exchange for reduced carbon. Actinorhizal plants represent a diverse group of about 220 species belonging to eight plant families distributed in the three orders, Fagales (Betulaceae, Casuarinaceae and Myricaceae), Rosales (Rosaceae, Eleagnaceae and Rhamnaceae) and Cucurbitales (Datiscaceae and Coriariaceae) (Wall, 2000; Pawlowski, 2009; Franche and Bogusz, 2011). All actinorhizal species belong to the Rosid I clade, thus sharing a common ancestor with legumes (Fabaceae), but differing from them in their wide distribution in numerous botanical families."
Biological nitrogen fixation in non-legume plants

Thanks Jane.

I'm not having any problems with the plants - I was thinking about planting some perennial nitrogen fixers on the plot but now it turns out I've got a hedge of them.

I had thought that it may only had been a few plants in the rose family that fixed nitrogen but with the internet and Chinese whispers it became attributed to the whole group but it's nice to know it is the whole group.

So apples, pears, plums, strawberries, blackberries, raspberries, hybrid berries etc are all part of the rose family so should also help fix nitrogen right.

Yippee looks like i've got quite a few nitrogen fixers already.

Thinking about it - this explains why half the comfrey on my first plot is thicker and taller than the other half. The lusher half is next to a thornless blackberry I have growing up an arch.

Doubly good news with all the comfrey plants I'm planting underneath the hedge - a free self supporting fertility hedge.

It needs looking into it a bit more,I've been reading this;
"of 122 genera in the Rosaceae, only 4 genera are capable of fixing nitrogen. All these families belong to the orders Cucurbitales, Fagales, and Rosales, which together with the Fabales form a clade of eurosids. In this clade, Fabales were the first lineage to branch off; thus, the ability to fix nitrogen may be plesiomorphic and subsequently lost in most descendants of the original nitrogen-fixing plant; however, it may be that the basic genetic and physiological requirements were present in an incipient state in the last common ancestors of all these plants, but only evolved to full function in some of them:"
https://en.m.wikipedia.org/wiki/Nitrogen_fixation

"The Dryadoideae subfamily of the Rosaceae consists of four genera,[1] all of which share root nodules that host the nitrogen-fixing bacterium Frankia.[2] They are sub-shrubs, shrubs, or small trees with a base chromosome number of 9, whose fruits are either an achene or an aggregate of achenes.
https://en.m.wikipedia.org/wiki/Dryadoideae

I don't know which of the rose species have nitrogen fixing capabilities,or the name for hawthorn if it's a dryadoideae?

So we're back to the idea that it's only a few plants in the rose family that fix nitrogen and that those sites which mentioned hawthorn have incorrectly attributed it to the whole family.

I guess that the lush half of the comfrey is just getting that little bit more sun.

Ah well the comfrey under the hedge is still using dead ground I can't otherwise use and will still benefit from leaf fall.

Bang goes that excuse for planting more strawberries (not that I need an excuse )

Now where can I put that Siberian Pea Tree?