When we talk about fertilization in forestry, the conversation usually revolves around nitrate or ammonium — the “inorganic” forms of nitrogen that dominate industrial fertilization. But nature has another way.
Research on Populus species — the family that includes poplar and aspen — is revealing something remarkable: these trees don’t just tolerate organic nitrogen. They prefer it.
And this preference may hold the key to more sustainable forestry, with higher nitrogen efficiency, less leaching, and better long-term resilience.
For a long time, scientists assumed plants could only absorb nitrogen once it was converted into inorganic forms by soil microbes. That idea is now being rewritten.
In the study “Amino acid uptake: A widespread ability among boreal forest plants”, researchers measured how roots of Populus tremula (European aspen) absorbed amino acids directly from their surroundings.
Populus showed an uptake rate of 0.67 ± 0.07 µmol g⁻¹ root DW h⁻¹ — on par with many evergreen species.
The trees relied on ectomycorrhizal (EM) associations to support this amino acid uptake.
In simple terms: poplars can draw nitrogen from organic molecules like arginine and glutamine, skipping the microbial middleman.
That means they can tap into nitrogen sources often considered “locked away” in organic matter — a huge ecological advantage in boreal and temperate soils.
The next question scientists asked was: does organic nitrogen actually make a difference?
The answer came from a 2016 study published in Plant, Cell & Environment titled “The carbon bonus of organic nitrogen enhances nitrogen use efficiency.”
Poplar seedlings (P. tremula) were grown on sterile agar plates and fed either:
Inorganic nitrogen (as nitrate or ammonium), or
Organic nitrogen (as arginine or glutamine).
The sterile setup ensured that only the plant — not microbes — was responsible for nitrogen uptake and use.
The results?
Poplars fed with organic N used carbon more efficiently per unit of nitrogen absorbed.
The “carbon bonus” from organic N improved nitrogen use efficiency (NUE) and favored root growth and allocation.
This suggests that poplars using amino acids like arginine may develop stronger roots — a finding that aligns closely with Arevo’s field data on increased root biomass and survival in seedlings fed with arginine-based nutrition.
While young poplars can thrive on organic nitrogen, what about mature trees?
That’s what the 2022 Physiologia Plantarum paper “Nitrate fertilization may delay autumn leaf senescence while amino acid fertilization does not” set out to discover.
Using Populus genotypes from the Swedish Populus (SwAsp) collection — representing populations from Dorotea and Umeå — researchers compared different nitrogen treatments:
Nitrate-based (NH₄NO₃)
Amino acid-based (arginine, glutamine, glutamic acid, leucine)
They even tested “precision fertilization” by injecting nutrients directly into tree trunks within clonal stands — a method that mimics controlled nutrient delivery, similar in concept to Arevo’s root-zone application.
The findings:
Nitrate delayed autumn senescence, extending the leaf life artificially.
Amino acid fertilization did not alter seasonal timing, meaning the trees followed their natural cycle.
High concentrations of amino acids had no negative effects — proving arginine’s safety and compatibility.
The takeaway?
Arginine supports growth without disrupting the tree’s seasonal rhythm — a key factor in maintaining resilience, dormancy, and overwintering capacity in northern forests.
Finally, Populus trees stand out for another reason — their dual mycorrhizal associations.
Research on Populus angustifolia and P. tremula shows that they can form both arbuscular (AM) and ectomycorrhizal (ECM) partnerships, adapting to temperature and soil conditions.
This duality allows poplars to thrive in diverse environments — from rich lowlands to cold boreal soils — and likely enhances their ability to take up organic nitrogen.
By pairing arginine-based fertilization with natural mycorrhizal networks, we can replicate this efficiency in forestry and nursery systems.
Together, these studies paint a consistent picture:
Poplars can absorb and thrive on organic nitrogen like arginine.
Organic N enhances efficiency, root development, and natural growth cycles.
Amino acid fertilizers, such as arGrow from Arevo, work with nature’s systems — not against them.
In forestry, where nutrient loss and nitrogen leaching are persistent problems, this science offers a real alternative: a nutrition system that matches the tree’s biology.
Poplars are showing us the way forward — and the future of fertilization might just be a little more organic.
“Effects of early, small-scale nitrogen addition on germination and early growth of Scots pine (Pinus sylvestris) seedlings and on the recruitment of the root-associated fungal community.” (Study referencing Populus angustifolia mycorrhizal formation and temperature response.)
“Nitrogen-compounds-in-soil-solution-of-agricultural-land.” (Notes the presence of Populus tremula in a thinned birch forest site.)
Fataftah, N. et al. (2022). “Nitrate fertilization may delay autumn leaf senescence while amino acid fertilization does not.” Physiologia Plantarum, 174(2).
Franklin, O. et al. (2016). “The carbon bonus of organic nitrogen enhances nitrogen use efficiency.” Plant, Cell & Environment, 39(8): 1672–1683.
Robinson, N. et al. (2023). “Dual mycorrhizal colonization in poplar species: implications for nutrient uptake and carbon transfer.” Trends in Plant Science, 28(5).
Näsholm, T. et al. (2009). “Uptake of organic nitrogen by plants.” New Phytologist, 182(1): 31–48.