Small amounts of anthropogenic soil demonstrated a powerful effect on the growth of two species interesting for reforestation
By André Julião
A study carried out in Amazonas with support from Fapesp demonstrated that small amounts of the so-called “terra preta da Amazônia” (TPA), anthropogenic soil created by ancient Amazonian populations, are capable of increasing growth by up to 55% in height and 88% in diameter of purple ipê (Handroanthus avellanedae), a tree that also occurs in the Atlantic Forest.
In an Amazonian species, the paricá (Schizolobium amazonicum), the increase was 20% in height and 15% in trunk diameter. The results refer to the first 180 days of the plants’ life, compared to others of the same species that did not receive terra preta.
The research, in the magazine BMC Ecology and Evolutionwas conducted by researchers from the Center for Nuclear Energy in Agriculture at the University of São Paulo, in Piracicaba, Embrapa Amazônia Oeste and Inpa (National Institute for Amazonian Research), both in Manaus.
“The determinant was not the amount of nutrients itself, which doesn’t change much, but the microorganisms, which were very different, especially the fungi. In plants treated with terra preta there is a reorganization of the microbiota around the roots, with a more efficient recruitment of beneficial microorganisms and a reduction in pathogens”said , 1st author of the study, carried out during his doctorate at Cena-USP with Fapesp.
In addition to helping to reforest degraded areas and provide ecosystem services, the two trees analyzed can be used in the sustainable exploitation of wood, especially ipê-roxo.
The work is part of the project “”, supported by Fapesp and coordinated by , professor at Cena-USP.
Terra ancestral
The black lands of the Amazon or black Indian lands (TPI), as they are also known, result from the decomposition of organic matter and the use of fire by pre-Columbian populations and continue to be created by current people (read more in ).
The study shows that TPAs house a set of bacteria, archaea and fungi that help plants absorb nutrients and also eliminate other opportunistic and pathogenic microorganisms, making the environment much more favorable for their growth.
“We have studied black lands for over 20 years and tested different ways of using them. The idea is to understand what is best for trees to grow faster and stronger in degraded areas”said Tsai.
“When deforestation is carried out, especially for pasture, the soil tends to be poorly managed, which leads to a very rapid loss of microorganisms and nutrients. The objective is to recover the forest and ecosystem services in these areas”he declared.
Protected by law, black lands are regulated by the CGen (Genetic Heritage Management Council), a collegial body chaired by the Ministry of Environment and Climate Change.
“We use small amounts in experiments, after obtaining authorization from CGen. The idea is not for people to use it directly, which is prohibited, but to understand how it is formed, what its content is and which microorganisms and processes make it so special. With this, we could reproduce it or isolate its components that could be useful”said Freitas.
Experiment
In a previous study, the group compared growth in a greenhouse, with and without the addition of terra preta, of seedlings of other tree species and brachiaria grass (read more).
In the current work, the growth of seedlings in the field was measured. For this, seeds of the two species were cultivated in the Embrapa Amazônia Oeste nursery, in Itacoatiara (AM), in 2 treatments: black earth or coconut fiber.
After 15 days, the seeds had germinated and become seedlings, which were then transferred to the experimental field of the same institution, in Manaus. They were planted in the ground and did not receive any fertilizer or herbicide, receiving only rainwater and manual control of weeds.
After 6 months, all plants were alive. However, the differences in those treated with TPA were significant. In the case of paricás, although they showed proportionally smaller growth than what occurred among ipês-roxos, the trees were around 1.5 meters tall 180 days after the seedlings were transferred to the field.
The researchers observed in the soil of plants treated with terra preta an increase, mainly, in the diversity of fungi, more pronounced in the ipê-roxo. The explanation may be the great adaptation of the paricá to degraded soils, which means that the species does not require as many nutrients and microorganisms.
“Fungi respond faster, as they are more complex microorganisms. With the addition of terra preta, there is an immediate increase in organic matter and, therefore, in decomposer fungi, which cycle nutrients more efficiently, making them more available to plants”explained Freitas.
The results published now refer to the first 180 days of the plants’ life. In total, the experiment lasted 3 years. Currently, researchers are analyzing data from the entire period, which will result in new work.
In more than 20 years of studying black earth, the laboratory led by Tsai at Cena-USP has more than 200 microorganisms isolated from these formations, which are now being analyzed for their functions. The idea is to develop solutions that can be applied to recover degraded soil for reforestation.
The work was supported by Fapesp through Cena-USP for another co-author of the study, .
The article Boosting tree growth in the Amazon rainforest using Amazonian Dark Earths can be read.
This text was originally published by on March 24, 2026 and adapted for publication by Poder360.
