The study evaluates the effects of wood biochar as a soil amendment on aerobic rice cultivation in Brazil's tropical savannah, focusing on its impact on soil properties and crop performance over multiple seasons. Biochar application was found to decrease soil acidity and improve water retention, although its effects on rice yields varied based on soil type and nitrogen fertilizer use. The research suggests that while biochar can enhance soil quality and reduce greenhouse gas emissions, additional nitrogen fertilization may be necessary for optimal rice yield increases.

1. The impact of wood biochar as a soil
amendment in aerobic rice systems of the
Brazilian Savannah
Wageningen, 2 February 2015.

2. The Brazilian tropical Savannah
42% of overall crop production in Brazil is coming
from the Central West Region

3. Rice systems
Brazilian Savannah:
Non-flooded (aerobic/rainfed)
50% area - 30% productivity
South Brazil:
Flooded
50% area – 70% productivity

4. Sandy Plinthosol Clayey Ferralsol

5. Large yield gap
• Actual yield ≤ 1 t/ha  attainable yield ≥ 5 t/ha
• Causes:
• Biotic stress
• Rice blast (disease) and weed infestations
• Weathered soils
• Acidic
• Low soil organic matter content
• Poor nutrient availability
• Water stress (deficit) due to erratic rainfall:
critical period between panicle initiation and
flowering

6. Critical period
Optimal:
220 to 250 mm
30-33ºC
Growing period of Aerobic rice
650 – 750 mm / 20 – 35ºC
Sowing HarvestingFloweringPanicle
initiation
End of
Tillering
Sterile spikelets -> unfilled grains

7. Wood biochar
Forest Plantation ---- Slow carbonization-- Wood charcoal
(Eucalyptus sp.) (low concentration of
Oxygen)
Pieces ≤ 8 mm is a BY
PRODUCT and can be
used as BIOCHAR

8. Biochar as a soil amendment
 Decrease acidity (liming effect)
 Increase soil nutrients availability
 Increase water retention
 Potential increase in crop yields ~ 10%
 Positive effects mainly from:
● Artificially controlled conditions (pot experiments)
● Rates of biochar higher than 2% w/w
● Short term experiments (1-2 years)
● Other crops than rice

9. Objectives
 Quantify the effect of wood biochar amendment and its
combination with mineral N fertilizer on aerobic rice crop
performance on a sandy (non-irrigated) and clay soil
(irrigated) of the Brazilian tropical Savannah
 Analyse the effect of wood biochar amendment on soil
physical and chemical properties throughout 4 rice
seasons after biochar application
 Monitor the effect of wood biochar amendment on
N2O-N fluxes throughout crop seasons

10. Research design
• BIOCHAR: 4 levels (0, 8, 16 and 32 t/ha) incorporated once to
a depth of up to 15 cm
• NITROGEN: 4 levels (0,30, 60 and 90 kg/ha) applied annually
• SOIL TYPE (2 sites): Sandy soil in Mato Grosso (rainfed) and
Clay soil in Goias (rainfed + irrigation)
• 4 Blocks with 4 repetitions = 64 plots of 40 m2 in each site
• TIMESPAN, years after biochar application in soil:
Clay soil: 5 seasons S0.0, S0.5, S1.5, S2.5, S3.5
Sandy soil: 4 seasons S0, S1, S2, S3

11. Preparation of field experiments

12. The soil water retention
 In the sandy soil: biochar
increased the rice
available water in 5-10
cm at 2 and 3 years after
application
 In the clay soil: biochar
decreased soil bulk
density and rice available
water in 5-10 cm at 1.5
and 2.5 years after
application

13. The soil acidity
 In both soil types:
biochar decreased soil
acidity (measured as
the increased soil pH)
 The effect lasted up to
3 years in the sandy
soil and up to 1.5
years in the clay soil
a) Sandy soil
b) Clay soil

14. The soil organic matter
 In the sandy soil: biochar
hardly (or not) affected
the soil organic matter
content
 In the clay soil: biochar
increased the soil organic
matter content with time,
at 2.5 and 3.5 years after
application
a) Sandy soil
b) Clay soil

15. The rice performance
 Varies according to soil
type and season
 In the sandy soil: very
positive or no effect on
grain yield
 In the clay soil: no effect,
negative or a positive
effect depending on the N
fertilizer applied
*Adapted from Petter et al. (2012)
a) Sandy soil
b) Clay soil

16. Greenhouse gas emission measurement:
static chambers to measure N2O-N fluxes

17. The effect of biochar on GHG emission
(Nitrous oxide: N2O-N fluxes)
 Biochar would reduce
N2O-N fluxes:
1) first, due to a decrease
in soil N availability
2) with time, due to
increased capacity of soil to
retain mineral N
 The effect of biochar on
soil water could trigger
N2O-N fluxes due to
aerobic/anaerobic
conditions

18. No interaction effect of biochar and the N fertilizer

19. Contribution to sustainable intensification
of farming systems in a tropical Savannah
The type of wood biochar used in this study:
• Can be used as an alternative to soil liming and
supplementary mineral fertilization
• Can be used as an strategy to increase water retention
in sandy soils
• Can be used as an amendment to enhance the soil
organic matter content in clay soils with time
• Rate up to 32 t/ha was not sufficient to guarantee an
increase in aerobic rice yield, and complementary
mineral N fertilization is likely to be needed.

20. Funding

21. Obrigada!
Thanks!
Bedankt!
“Life isn’t a game, friend.
Life is the art of the
encounter.
Even though there might
be so much discord (dis-
encounter) in this life.”
(Samba da Bênção, 1967)