Improving soil health and production of fodder legume
Stylosanthes using biochar from rice husk residues in ASAL soils
Elizabeth Awuor Ouna
PhD Candidate, UoN
SUPERVISORS:
Dr. Wanjogu R. K. -NIB
Prof: Gachene C. K. -UoN
Prof: Njoka J. –UON
Introduction
•Food insecurity in ASALS is associated with degraded soils and high cost of chemical fertilizers
which cause cause of poor yield and low quality fodder.
•. Economic contribution of livestock: ASALs of Kenya: -sustains 90% of dryland livelihoods and
supports 10% and 40% of GDP at national and agricultural levels(Govt of Kenya, 2004).
•Losses: nded drought: External 2004 and 2006 estimated at US$387 million and US$1.3 million
(GoK, 2009) on emergency food and feed relief.
•Annual rice production in Kenya is 83,000MT about 20% estimated at 16,600 MT of rice husk –
or related biomasses including wheat and maize cobs & other feedstocks which may form a
valuable resource for the production of biochar to improve soil fertility and reducen cost of
fertilizer improve yield of forage legumes such as Stylosanthes in ASALs.
Existing gaps : improve feed quality through diversify fodder grasses and legumes using sibling
varieties adapted to dryland ecosystems.
Agronomic performance of biochar based on physico-chemico-properties, chemical and
physical, effect on plant rhizosphere may facilitate in improving yield to reduce high consumer
demand and livelihoods of small holders..
• Challenges of biochar application: quality of feedstock and soil types.
Justification
•Low nitrogen and phosphorous concentration in the soils result in
production of low quality forage and high cost of feeds.
•Sustainable farming practices-which improve soil health recycling
agricultural wastes is an environmentally friendly.
Rice husk heaps in Mwea
• High ETO in the ASALs demand for water conservation practice that
retain water for longer periods in soil and or which can unlock the
osmotic potential of clay soils to improve porosity, bulk density or vital
physical processes such as aeration and hydrology to sustain production.
•Cultivation in clay soils is restricted to a narrow range of water contents
of storage micro-pores which create high water sunction.
-Application ofbiochar to unlock critical soil-water sunction usually at 1.5
MPa in clay soil due to residual micropores which block air entry of air.
Burnt rice-husk
Objectves
Overall objectives
To determine suitable biochar that will improve soil health and yield of legume
Stylosanthes in Mwea and Bura
Specific objective :
1. To improve quality of rice husk biochar
2. To evaluate effect of biochar soil amendment on physical and chemical
properties of soil and yield of Stylosanthes
Research Hypothesis
H01:
There are no differences in quality of biochar produced from traditional
and improved carbonizer
H02:
Rice-husk biochar does not improves water use efficiency in Vertic and
sandy loam soil.
.
Materials and Methods
Sampling for Baseline data and Experimental site:
Sampling was carried out at the beginning of cropping season.
Mwea Irrigation scheme.
The region lies at longitude037° 18’ 18 E; 037° 21’ 55 E; latitude 00° 43” 02 s 00°
39’ 08 ; S1100 -1230 msl
It is divided into 6 sections; Karaba, Thiba, Wamumu, Tebere, Mwea, Ndekia; 30
to 61 units each unit measuring between 300-500 acres; sub-divided into 1
acre; linearly arranged on homogeneous soil.
Bura irrigation scheme: It lies 39° 20” E; & 30”00° 45” S and 1° 30” S; 112 msl;
rainfall of 300-400 mm per year in bimodal; ETO> precipitatn by 2.
Du etovariation of soil texture due to abrupt chanesof discontuty of
soiltexture.nd Purposive method sampling was used for selection of units in a
total of 9 units.
Replicate sets of composite samples was samples using auger at depths of 015 and 15-45 cm within each acre at a distance 40 m apart expermental site 9
cores were taken systemically after every 2 alternative sub-units.
A total of 24 samples/unit, dried in laboratory after chopping into small pieces
and air drying in closed room for 2-3 d at about 40 °C. The soil was ground to 2
mm diameter for analysis.
• The samples were dissolved in hydrogen peroxide to oxidize organic matter
Extraction of total Nitrogen using back titration method
•
•
•
Measurement of 0.5 g of dried soil ground to approximately 0.2 mm diameter was weighed
and transferred into digestion tube. Concentrated sulphuric acid and 30% hydrogen peroxide
added to destroy organic matter .
The mixture was left to stand or a period of 8 h. Extract of (NH+4)2 SO4 a will be decanted
from the mixture and filled to 100 ml with distilled water.
Distillation and separation of NH4 OH: Measurement of 10 ml of NaOH was added to add 20
ml of the extract (NH4SO4). Water in a distiller was heated to boiling to release free
ammonium by steam distillation (NH4+ has low boiling point).
Determination of total carbon content (redox reaction)
• Measurement of 0.1 g of soil will be weighed and mixed with 20 mls of concentrated
sulphuric acid and 10ml of K2Cr2O7 mix and left to stand for a periods of 30 minutes.
Water will be added up to 200mls of distilled water. Then add 0.5 g of Sodium flouride
(NaF) and 1 ml of indicator (diphenylamine). Blank will be prepared to contain all the
above ingredients except soil. FeSO4 will be titrated on blank to get volume of unreacted. Carbon content will b determined by mixing potassium dichromate with
carbon and sulphuric acid. (NH4)2SO4 + 2 NaOH = NH4OH + Na2 SO+4
.
•
Sodium hydroxide will be titrated with 0.005N H2SO4; 2NH4OH + 0.005 N H2SO4 =
(NH+4)2SO4 + H2O.
Materials and Methods
Experiment 1: Improving quality of rice husk biochar
Traditional kiln: The inner core of the kiln was filled with
material and ignited from the bottom. Rice husks is then
heaped.
Traditional kiln
On lab-scale carbonizer: rice husk biomass was packed in the
bed of a low through-put laboratory scale carbonizer.
Electrical blower /control fan was switched on before ignition
and immediately put at the lowest pressure in a tunnel fitted
with two dampers.
.Pyrolysis temperature was recorded using a thermocouple.
Residence time of carbonization.
Slow pyrolysis
Laboratory scale
carbonizer
Thermocouple
After pyrolysis biomass of carbonized husks was weighed, and
analyzed for % age production and rate of carbonization..
The product was later used for experiments (biochar weighing)
Product weighing Lehmann, 2009
Experiment 2: Effect of Biochar on Physical properties of soil
•
Experimental plot the field was flooded to saturation for a period of one week. Rotavated to a
depth of 10 cm using a tractor and soil leveled using oxen and drained to field capacity.
•
Dry bulk density biochar, clay vertic soil of non amended, water content (g/g ) of oven dried soil
= 41.17 g, density of dry soil/100cm3 and porosity.
•
At 3 ton ha-1 and water retention at and porosity of 52.8%; amended soils percentage and
particle density of organic soils of 3%, 2.58 g cm-3 ;10%, 2.43 g cm-3; and 30%, 2.09 g cm-3 is
currently in progress
Materials and Methods
Experiment 2: Effect of biochar soil amendment on physical and chemical
properties of soil and yield of Stylosanthes
Seeds of S. hamata, S. scaba and S. seabrana received from ILRI germplasm
were scarified and sterilized with concentrated sulfuric acid (80%) for a
period of 10 minutes; followed by rinsed in 5 changes of sterile water.
They will be kept overnight in moist petri-dish lined with filter paper and
incubated to imbibe under refrigerator at 4 °C overnight after which rinsed
again with two changes of sterile distilled and directly planted in planting
bags at a rate of 3 seedlings per hole and later thinned to1 plants per hole.
.Legume growth rate, shoot and dry weight were measured and harvested at
vegetative pre vegetative stages 10, 20 weeks, 50% flowering and maturity.
Data and total level of crude protein and phosphorous accumulation, in the
plant shoot shoot at post harvest.
Initial weight of shoots was measured and 105 °C for kept in oven at 3 days
to dry. Quality of the feed –to be done (crude protein, fiber content, fat and
total digestible nutrients of DM) compare nutritive value among 3 varieties
of Stylosanthes
Dry matter of the forage was harvested and covered shade to cut off
sunlight and wind draught constructed outside the ground to reduce on loss
of nutrients from a single cut field and single variety
Experimental designs
RCBD design will be applied to experimental units in. Each unit were divided
in 3 replicate blocks, further subdivided into plots measuring 4 m by 5 m.
The plots were amended biochar at 3 ton per ha
from traditional kiln (TBCA) and improved biochar (IBCA).
Control plots for each variety were not amended with biochar but received TSP
application and Nitrogen at planting a rate of 50 kg/ha in Mwea soils and
Bura respectively.
Soils were later collected at the rhizosphere of of Staylosanthes varieties at 015 cm and 15-30 cm using a soil auger and samples treated as earlier stated
for chemical analysis.
Data Analysis
• Mean biomass, number of stems and plant height were
determined using one way analysis of varience . Data on
number of stems and biomass (branches) was normalized by
arcsine transformation.
• One way ANOVA used for fanalysis using PROC. GLM
procedure of Genstat.
• Means wer4e separated using Turkeys standardized range
test.
Results
Thermal conversion process between traditional Kiln and low-throughput carbonizer
Kiln type type
Temp range °C
Residence time
(min)
rate(C/sec
%-age
productn
800
Traditional Kiln
Highly variable
112- 350
349.8 46
736 ± 56
30 ±2.1
112-350
60
600
temp 1
400
temp 2
Improved
carbonizer
2.13
55
200
temp 3
0
o 10 20 30 40 50
time (mins)
Baseline data of soil chemical properties in Mwea Irrigation scheme collected at different Depths
Scheme
Location
Depth
(cm)
%N
P
(ppm)
K
(me/100g)
0-15
15-45
0.08-0.13
0.09-0.14
22-36
24-36
0.09-0.12
0.08-0.17
0.82-1.18
0.78-1.1
0-15
15-45
0.07-0.11
0.03-0.12
15-30
15-34
0.09-0.21
0.04-0.33
-
4.7-6.5
4.8-6.5
15-45
0-15
0.02-0.10
0.03-0.17
9-23
10-24
0.09-0.17
0.09-0.17
-
-5.3-6.7
5.4-6.7
Karaba
0-15
15-45
0.02-0.10
0.06-0.16
13-23
6-24
0.04-0.17
0.04-0.17
-
5.6-9.0
5.6-7.0
Wamumu
0-15
15-45
0-15
15-45
0.08-0.14
0.03-0.11
0.03-0.16
0.06-0.10
3-19
3-22
16-21
17-22
0.04-0.25
0.09-0.25
0.09-0.17
0.09-n0.17
-
5.3-6.7
5.6-6.4
5.9-6.7
6.0-6.6
0-15
15-45
0.07-0.13
0.06-0.15
19-23
16-23
0.04-0.17
0.04-0.17
-
5.6-6.1
5.5-6.1
Ndekia/
Nyangati DL
0-15
15-45
0.09-0.11
0.07-0.10
23-28
19-24
0.09-0.17
0.12-0.17
-
5.6-5.8
5.4-5.6
Ndekia FB
0-15
15-45
0.11-0.19
0.10-0.11
54-116
85-102
0.12-0.17
0.08-0.17
-
5.04-5.1
4.71- 5.0-
Mwea
MIAD
Research
Mwea Unit 4
Mwea Unit 11
Ndekia Unit 1
Ndekia Unit 2
% Org.-C
pH
5.9-7.1
6.0-6.6
ECe
204-344
300-415
-
Bura ph at 15-30 cm depth ranges from;N of; P of.0; K value of And
ECe value of respectively.
•
Scheme Location
(cm)
%N
P
(ppm)
K
(me/100g)
0-15
15-45
0.08-0.12
0.08- 0.09
29-36
32-39
0.09-0.76
0.254-0;.
-
7.8-8.6
7.7-8.3
572- 657
419-630
Village 1
0-15
15-45
0.06-0.09
0.05-0.08
33-40
31-36
0.38-0.64
0.170-0.63
-
7.45-7.8
7.38-8.1
215 - 621
1.317-359
Village 5
0-15
15-45
0.07-0.09
0.06-0.10
49-57
52-53
0.42-0.55
0.16-0.55
-
7.7-8.7
7.6-8.2
236 - 618
162 - 858
Village Unit 6
0-15
15-45
0.07-0.98
0.074-0.11
30-36
30-39
0.509-0.721 0.509-0.678 -
7.04-8.11
7.4 - 7.8
Village 10
0-15
15-45
0.06-0.09
0.06-0.10
49-57
49-51
0.42-0.55
0.34-0.68
7.8-8.1
7.5-8.1
313 -617
138 -604
0-15
15-45
0.063-0.102 58-113
0.049-0.070 56-65
7.11- 7.92
7.36 -8.02
1.647-197
251-297
•
Bura Bura Research
Village
7
Depth
(µs/cm)
% Org.-C
-
0.254-0.509 0.297-0.594 -
pH
ECe
272-993
518-521
Comparison of physico-chemical quality soils amended with biochar (3 ton ha-1) at
different depths and developmental stages of Stylosanthes in Pelli-Vertic soils(Mwea)
Variety
s.Devpt
Trt
N
P
K
%C
pH
Bulk WHC
density
S. hamata 50%
flw
Control
TBCA
0.11 ± 0.01
0.18± 0.01
S. Scabra
control
TBCA
0.12 ± 0.01b 51 ± 6
0.19± 0.03 a Excess
50%flw
S. seabrana 50%flw
control
TBCA
55 ± 1
Excess
0.12 ± 0.02
0.11 ±0.01
1.11
1.13
0.15 ± 0.02 b 1.1± 0.1
0.21 ± 0.04 a *
5.5± 0.2
5.6 ± 0.1
5.6± 0.0
6.1± 0.5
0.89
Effect of Biochar soil amendment on shoot Biomass of varieties Stylosanthes in Pellicvertic soil of Mwea
Variety
TRT
Veg.
S. hamata
Control
TBCA
4.83 ± 0.12 b
5.60 ± 0.26 a
91.3 ± 12 b
174.3 ± 30.2 a
398.7 ± 4.8 b
651.3 ± 41 a
57.1
92.9
S scabra
Control
TBCA
0.90 ± 0.03 a
1.05 ± 0.23 a
35.3 ± 2.9 b
62.5 ± 2.7 a
224.0 ± 28 a
236 ± 14 a*
89.9
51.2
1.05
2.18
1.39 ± 0.16
**
84.0 ± 7.0 b
99.0 ± 6.7 a
366 ± 12 b
434 ± 5.3 a
67.42
227.2
0.67
0.78
S. seabrana Control
TBCA
50% flow.
Maturity
SDM (g)
L:S
ratio
0.776
0.98
Effect of Biochar soil amendment on shoot Biomass of
Stylosanthes varieties in vertic soils
Variety TRT
Veg.
50% flw
Maturity
S. hamata
Control
TBCA
4.83 ± 0.12 91.3 ± 12
5.60 ± 0.26 174.3 ± 30.2
398.7 ± 4.8
651.3 ± 41
S. scabra
Control
TBCA
0.90 ± 0.03 35.3 ± 2.9
1.05 ± 0.23 62.5 ± 2.7
224.0 ± 28
236 ± 14
S. seabrana
Control
TBCA
1.39 ± 0.16 84 ± 7.0
*
98.95 ± 6.7
366 ± 12
434 ± 5.3
Comparison of physico-chemical quality soils amended with biochar (3 ton ha-1) at
different depths and developmental stages of Stylosanthes in vertic soils (Mwea)
Variety
TRT/soil
depth (cm)
Pre-Vegetative 1-15
S. scabra
Control
TBCA
IBCA
S. scabra
S. hamata
15-30
Control
TBCA
IBCA
0-15
Control
TBCA
IBCA
Control
TBCA
S. hamata
Control
TBCA
N
Vegetative
P
%C
0.13
0.05±0.01
0.04±0.09
29
1.18
39.8 ±7.4 1.36± 0.1
45 ±12
1.25 ±
6.5
6.6
6.3± 0.2
22-36
0.12 ±0.06 36.1± 4.2
0.167±0.01 43.2± 8.7
0.12 ± 0.01
0.05 ±0.01
0.04 ± 0.0
51 ± 6 .1 1.1± 0.1
58 ± 15 1.31 ±0.19
38 ± 17 1.30 ±0.01
5.6± 0.0
6.8
6.3 ± 0.0
0.063±0.02 37 ±9.8
0.05 ± 0.01 34 ±5.4
0.11±0.01
0.18± 0.01
55 ± 1
Excess
pH
1.11 5.5± 0.2
1.13 5.6 ± 0.1
N
P
Maturity
%C
pH
Bulk
density
1.18
6.5
1.
1.14 ±0.6 6.6±0.1 0.187*
1.33 ±0.1 6.6± 0.1
1.36 ± 0.09
1.13 ± 0.1
6.8 ±0.14
6.8 ± 0.2
WHC
Effect of Biochar soil amendment on no. stems (branches) of Stylosanthes varieties in
Vertic soils
Variety
TRT
Veg.
50% flowering
Maturity
S. hamata Control
TBCA
6.8 ± 0.43 b
7.5 ± 0.31 ab
76.1 ± 6.0 b
116.1 ± 6.9 a
505.6 ± 9.9 b
805 ± 62.7 a
S scabra
4 ± 0.5b
3.4 ± 0.13 ab
8.5 ± 1b
27.4 ± 5.8 a
204.5 ± 28.1 a
229 ± 67 a
S. Seabrana Control 4.5 ± 0.17 a
TBCA
4.85 ± 0.17 a
47.4 ± 4.7 b
95.5 ± 4.6 a
519.9 ± 8.9 b
560.5 ± 13.9 a
Control
TBCA
Bura Results: Percentage (%) germination of 3 varieties of Stylosanthes in Bura
field station
Control
TBCA
IBCA
MZ
S.hamata
S. scabra
S. seabrana
11.0 ± 2.0
10.5 ± 3.9
13.6 ± 3.4
11.25 ± 1.0
7.9 ± 1.9
8.25 ± 0.25
8.0 ± 0.0
10.1 ± 1.7
49.5±6.2
48.7±4.1
42.5±4.5
40.7±3.4
High weed pressure
in Bura
Stylosanthes at Maturity (90 days after planting amendment
Control
TBCA
IBCA
Maize Cob
Height
stems
(branches)
Weight
57.85±1.1
62.1 ± 1.8
58.8 ±2.3
59.5 ±3.1
329±43
396 ± 36
358 ±25.6
386 ±
240 ± 5.8
267.5 ± 2.5
242.5 ± 9.6
242.5 ± 8.5
Conclusion
•
•
•
•
•
•
Biiochar from the two pyrolysisunits may be having difference in chemical concetration and
volatiles and the fast pyrolysis carbonizer need re-fabricationto to process biomas.s
Bochar caused slight increases soil pH in vertic soils and could have been the cause for
increased availability of phosphorus or improved aeration in the crop root zone and improved
soil water - holding capacity, increased levels of exchangeable potassium and improved
growth rate of S. hamata and S. seabrana.
Failure of S. hamata and S. scabra to grow due to weed pressure in Bura could be associated
to plant intolerance to high Sodium level and high soluble salts which prevent hydrolysis.
Biochar sol amendment significantly increased yield of Stylosanthes.
The experiment on effect of biochar amendement on on physical properties and water used
efficiency is on-going
EXPECTATION: 3 PUBLICATION IN Journ Bio-energy / Recycled Agric. waste and
Management
Thank You