This study examined the effects of applying different rates of biochar and nitrogen fertilizer on the growth and yield of aerobic rice grown in a clayey Rhodic Ferralsol soil in the Brazilian savannah. The study found that: 1) Biochar applications up to 16 Mg/ha did not negatively influence rice grain yield but higher rates of 32 Mg/ha reduced leaf area index and total shoot dry matter. 2) The optimal nitrogen rate to achieve a grain yield above 3 Mg/ha was 46 kg/ha. 3) Higher biochar and nitrogen rates increased soil ammonium and nitrate availability over the growing season.

1. Growth of AR in the presence of biochar as soil amendment:
short-term effects in a clayey Rhodic Ferralsol in the BS
Contact:
PhD Student Márcia T. de Melo Carvalho
Centre for Crop Systems Analysis
Wageningen University, The Netherlands
E-mail: marcia.demelocarvalho@wur.nl
a. Biochar applications did not influence grain yield of aerobic rice;
b. LAI and TDM was negatively related to biochar rates above 16 Mg/ha;
c. The optimal N rate was 46 kg/ha to achieve a grain yield above 3 Mg/ha.
Influence of biochar and N rates on leaf area index (LAI)
and total shoot dry matter (TDM) at 72 DAS:
Influence of N and biochar rates
on yield and spikelet fertility:
The Brazilian savannah (BS):
46% is covered by Ferralsols.
Aim: to report single season effects of
biochar application coupled with N
fertilisation on AR growth and grain yield
in a clayey Rhodic Ferralsol in the BS.
Aerobic rice (AR): rain fed,
grown on well drained soils.
The biochar: a by-product of charcoal
made from Eucalyptus sp. (pieces<2mm)
incorporated into 0.2 m soil depth, six
months prior sowing rice.
The native clayey Rhodic Ferralsol in the field experiment:
Constraints for AR in the BS:
erratic rainfall, low N recovery.
Difference in soil moisture in 0.1 m soil depth between treatments with
biochar (8, 16 and 32 Mg/ha) and without biochar over the growing season:
Averaged soil ammonium and nitrate availability (mg/kg) in 0.1 m soil
depth over the growing season:
NH4
+ 0.06349 N (p ≤ 0.05) + 16.83
NO3
- 0.5002 char (p ≤ 0.001) + 0.3357 N (p ≤ 0.001) + 43.85
Treatments:
4 levels of N (0, 30, 60 and 90 kg/ha)
and biochar (0, 8, 16 and 32 Mg/ha).
Season: Dec. 2008 to Feb. 2009.
Conclusions:
●0 □30 ∆60 ○90
●0 □8 ∆16 ○32
●0 □8 ∆16 ○32