Adding Amazonian temnozema (ADE) to soil can significantly accelerate plant growth, according to a study published by Brazilian scientists in the journal Frontiers in Soil Science. ADE, also known as terra preta, is highly productive due to its nutrient richness and stable organic matter. The researchers experimented with ADE and found that adding it to the soil accelerated plant growth and development and promoted greater bacterial and archaeal biodiversity. The study shows that ADE can be used to accelerate ecological restoration projects around the world.

Between about 450 BC and 950 AD Millions of Indians living in the modern Amazon, with the help of various processes, changed the originally poor soil. For generations, soils have been enriched with charcoal from low-intensity fires for cooking and burning garbage, animal bones, broken pottery, compost and manure. The result is the Amazon Dark World (ADE), or soil pretaIt is extremely productive because it is rich in nutrients and it is the stable organic matter from coal that gives it its black color.

Now scientists in Brazil are showing that ADE could be a “secret weapon” to speed up reforestation – not just in the Amazon, where 18%, or about 780,000 km2, has been lost since the 1970s, but all over the world. The results were published in the journal Frontiers in Soil Science.

“Here we show that the use of ADEs can enhance the growth of pastures and trees due to their high nutrient content and the presence of beneficial bacteria and archaea in the soil microbial community,” said co-lead author Luis Felipe Zagatto. Nuclear Energy Center at the Agricultural University of Sao Paulo, Brazil.

“This means that knowledge of the ‘components’ that make ADEs so efficient can be applied to accelerate ecological restoration projects.”

Miniature afforestation simulation

The researchers conducted controlled experiments to simulate the ecological succession and soil changes that occur when grasslands in deforested areas are actively converted to forest. Their aim was to examine how soils where ADEs, or ultimately the microbiome, were artificially assembled to mimic them, could accelerate this process.

Zagatto and colleagues obtained ADE samples from the Caldeirão Experimental Research Station in Amazonas state, Brazil, and agricultural soil from the Luis de Queiroz Agricultural College in São Paulo state as controls. To estimate global warming for current temperatures of 22 to 28ºC in the Amazon, they filled 36 four-liter pots with 3kg of soil each inside a greenhouse with an average temperature of 34ºC.

One-third of the pots received control soil alone, another third received a 4:1 mixture of control soil and ADE, and another third received 100% ADE. They planted sedge seeds to simulate a pasture (Urochloa brizantha), a common cattle feed in Brazil, each pot and its seedlings were allowed to grow for 60 days. Then they mow the grass and leave only its roots in the soil – a virgin area for miniature afforestation. The researchers then replanted each of the three soils with tree seeds: either a colonial species of Ambeya squash (Cecropia pachystachya), typical for secondary forests Peltophorum dubium or white cedar (Cedrela fissilis), characteristic of the peak forest.

The seeds were allowed to germinate and the seedlings were allowed to grow for 90 days, after which height, dry mass and root elongation were measured. The scientists measured changes in soil pH, structure, and concentration of organic matter, potassium, calcium, magnesium, aluminum, sulfur, boron, copper, iron, and zinc during the experiment. Using molecular methods, they also measured changes in soil microbial diversity.

It is rich in nutrients and beneficial microbes.

At baseline, ADE showed higher nutrient concentrations than the control soil: for example, 30 times more phosphorus and three to five times more than each of the other nutrient measured except manganese. ADE also had a higher pH and contained more sand and silt, but less clay. After experimentation, soils contained less nutrients than at baseline, reflecting plant uptake, but 100% ADE soils remained richer in these soils than control soils, while nutrient levels in 20% ADE soils were moderate.

Soils in the 20% or 100% ADE experiment supported more bacterial and archaic biodiversity than control soils.

“Microbes convert chemical particles in the soil into nutrients that can be absorbed by plants. Our data showed that ADE contains microorganisms that can better cope with this type of soil transformation, thereby providing more resources for plant growth,” said co-lead author Anderson Santos de Freitas.

“For example, ADE soils contained more beneficial taxa of the bacterial families Paenibacillaceae, Planococcaceae, Micromonosporaceae, and Hyphomicroblaceae.”

accelerated growth

The results also showed that adding ADE to the soil improved plant growth and development. Thus, for example, the dry mass of hedge turf increased 3.4 times at 20% ADE and 8.1 times at 100% ADE compared to control soil. The addition of ADE also accelerated the growth of three tree species: seedlings. household appliances And P. dubium were 2.1 and 5.2 times higher at 20% ADE and 3.2 and 6.3 times higher at 100% ADE compared to control soils. The Ambey pumpkin tree did not grow on control soils or at 20% ADE, but did grow at 100% ADE.

The researchers concluded that ADE can accelerate plant growth. “Our data show a mix of soil nutrients and adapted microorganisms. [в ADE] to improve the survival of woody plants during restoration,” they wrote.

Senior author Dr. Siu Mui Tsai warned: “ADEs took thousands of years to accumulate and would take the same time to regenerate in nature if used. Our recommendations are not to use ADE itself, but to replicate its properties, particularly microorganisms, for use in future ecological restoration projects.”