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. -NIBProf: Gachene C. K. -UoNProf: 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

Rice husk heaps in Mwea

•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.

• 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

Overall objectivesTo 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 HypothesisH01: 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.

.

Objectves

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 0-15 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 followed by digestion in sulphuric acid containing selenium to catalyse the process and salicic acid to bind the nitrates to determine total N and P.

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 un-reacted. 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

Traditional kiln Laboratory scale carbonizer

Slow pyrolysis Thermocouple

Experiment 1: Improving quality of rice husk biocharTraditional kiln: The inner core of the kiln was filled with material and ignited from the bottom. Rice husks is then heaped.

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.

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 hafrom 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 0-15 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.

Thermal conversion process between traditional Kiln and low-through-put carbonizer

Kiln type type Temp range °C Residence time (min)

rate(C/sec %-age productn

Traditional Kiln Highly variable112- 350

349.8 46

112-350 60

Improved carbonizer

736 ± 56 30 ±2.1 2.13 55

o 15 30 450

100200300400500600700800

temp 1temp 2temp 3

Results

time (mins)

Baseline data of soil chemical properties in Mwea Irrigation scheme collected at different Depths

Scheme Location Depth %N P K % Org.-C pH ECe(cm) (ppm) (me/100g)

MweaMIAD 0-15 0.08-0.13 22-36 0.09-0.12 0.82-1.18 5.9-7.1 204-344Research 15-45 0.09-0.14 24-36 0.08-0.17 0.78-1.1 6.0-6.6 300-415

Mwea Unit 4 0-15 0.07-0.11 15-30 0.09-0.21 - 4.7-6.5 -15-45 0.03-0.12 15-34 0.04-0.33 - 4.8-6.5 -

Mwea Unit 11 0-15 0.03-0.17 10-24 0.09-0.17 -5.3-6.7 -

15-45 0.02-0.10 9-23 0.09-0.17 - 5.4-6.7 -

Karaba 0-15 0.02-0.10 13-23 0.04-0.17 - 5.6-9.015-45 0.06-0.16 6-24 0.04-0.17 - 5.6-7.0

Wamumu 0-15 0.08-0.14 3-19 0.04-0.25 - 5.3-6.7

15-45 0.03-0.11 3-22 0.09-0.25 - 5.6-6.4

Ndekia Unit 1 0-15 0.03-0.16 16-21 0.09-0.17 - 5.9-6.715-45 0.06-0.10 17-22 0.09-n0.17 - 6.0-6.6

Ndekia Unit 2 0-15 0.07-0.13 19-23 0.04-0.17 - 5.6-6.1

15-45 0.06-0.15 16-23 0.04-0.17 - 5.5-6.1 Ndekia/ 0-15 0.09-0.11 23-28 0.09-0.17 - 5.6-5.8Nyangati DL 15-45 0.07-0.10 19-24 0.12-0.17 - 5.4-5.6 Ndekia FB 0-15 0.11-0.19 54-116 0.12-0.17 - 5.04-5.1

15-45 0.10-0.11 85-102 0.08-0.17 - 4.71- 5.0-

Bura ph at 15-30 cm depth ranges from;N of; P of.0; K value of And ECe value of respectively.

• Scheme Location Depth %N P K % Org.-C pH ECe (cm) (ppm) (me/100g)(µs/cm)

• Bura Bura Research 0-15 0.08-0.12 29-36 0.09-0.76 - 7.8-8.6 572- 657

15-45 0.08- 0.09 32-39 0.254-0;. 7.7-8.3 419-630Village 1 0-15 0.06-0.09 33-40 0.38-0.64 - 7.45-7.8 215 - 621 15-45 0.05-0.08 31-36

0.170-0.63 - 7.38-8.1 1.317-359 Village 5 0-15 0.07-0.09 49-57 0.42-0.55 - 7.7-8.7 236 - 618

15-45 0.06-0.10 52-53 0.16-0.55 7.6-8.2 162 - 858 Village Unit 6 0-15 0.07-0.98 30-36 0.509-0.721 - 7.04-8.11 272-993

15-45 0.074-0.1130-39 0.509-0.678 - 7.4 - 7.8 518-521 Village 10 0-15 0.06-0.09 49-57 0.42-0.55 - 7.8-8.1 313 -617

15-45 0.06-0.10 49-51 0.34-0.68 - 7.5-8.1 138 -604 Village 7 0-15 0.063-0.102 58-113 0.254-0.509 - 7.11- 7.92 1.647-197

15-45 0.049-0.070 56-65 0.297-0.594 - 7.36 -8.02 251-297

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

densityS. hamata 50% Control 0.11 ± 0.01 55 ± 1 0.12 ± 0.02 1.11 5.5± 0.2 flw TBCA 0.18± 0.01 Excess 0.11 ±0.01 1.13 5.6 ± 0.1 0.89

S. Scabra 50%flw control 0.12 ± 0.01b 51 ± 6 0.15 ± 0.02 b 1.1± 0.1 5.6± 0.0TBCA 0.19± 0.03 a Excess 0.21 ± 0.04 a * 6.1± 0.5

S. seabrana 50%flw controlTBCA

Effect of Biochar soil amendment on shoot Biomass of varieties Stylosanthes in Pellic-vertic soil of Mwea

Variety TRT Veg. 50% flow. Maturity SDM (g)L:S

ratio

S. hamata Control 4.83 ± 0.12 b 91.3 ± 12 b 398.7 ± 4.8 b 57.1

0.776TBCA 5.60 ± 0.26 a 174.3 ± 30.2 a 651.3 ± 41 a 92.9

0.98

S scabra Control 0.90 ± 0.03 a 35.3 ± 2.9 b 224.0 ± 28 a 89.9 1.05 TBCA 1.05 ± 0.23 a 62.5 ± 2.7 a 236 ± 14 a* 51.2 2.18

S. seabrana Control 1.39 ± 0.16 84.0 ± 7.0 b 366 ± 12 b 67.42 0.67 TBCA ** 99.0 ± 6.7 a 434 ± 5.3 a 227.2 0.78

Effect of Biochar soil amendment on shoot Biomass of Stylosanthes varieties in vertic soils

Variety TRT Veg. 50% flw Maturity S. hamata Control 4.83 ± 0.12 91.3 ± 12 398.7 ± 4.8

TBCA 5.60 ± 0.26 174.3 ± 30.2 651.3 ± 41 S. scabra Control 0.90 ± 0.03 35.3 ± 2.9 224.0 ± 28

TBCA 1.05 ± 0.23 62.5 ± 2.7 236 ± 14 S. seabrana Control 1.39 ± 0.16 84 ± 7.0 366 ± 12

TBCA * 98.95 ± 6.7 434 ± 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 Vegetative Maturity depth (cm) N P %C pH N P %C pH Bulk WHC

density

Pre-Vegetative 1-15 S. scabra Control 0.13 29 1.18 6.5 22-36 1.18 6.5 1.

TBCA 0.05±0.01 39.8 ±7.4 1.36± 0.1 6.6 0.12 ±0.06 36.1± 4.2 1.14 ±0.6 6.6±0.1 0.187* IBCA 0.04±0.09 45 ±12 1.25 ± 6.3± 0.2 0.167±0.01 43.2± 8.7 1.33 ±0.1 6.6± 0.1

15-30

S. scabra Control 0.12 ± 0.01 51 ± 6 .1 1.1± 0.1 5.6± 0.0TBCA 0.05 ±0.01 58 ± 15 1.31 ±0.19 6.8 0.063±0.02 37 ±9.8 1.36 ± 0.09 6.8 ±0.14IBCA 0.04 ± 0.0 38 ± 17 1.30 ±0.01 6.3 ± 0.0 0.05 ± 0.01 34 ±5.4 1.13 ± 0.1 6.8 ± 0.2

0-15Control 0.11±0.01 55 ± 1 1.11 5.5± 0.2

S. hamata TBCA 0.18± 0.01 Excess 1.13 5.6 ± 0.1IBCA

ControlTBCA

S. hamata Control

TBCA

Effect of Biochar soil amendment on no. stems (branches) of Stylosanthes varieties in Vertic soils

Variety TRT Veg. 50% flowering Maturity

S. hamata Control 6.8 ± 0.43 b 76.1 ± 6.0 b 505.6 ± 9.9 bTBCA 7.5 ± 0.31 ab 116.1 ± 6.9 a 805 ± 62.7 a

S scabra Control 4 ± 0.5b 8.5 ± 1b 204.5 ± 28.1 aTBCA 3.4 ± 0.13 ab 27.4 ± 5.8 a 229 ± 67 a

S. Seabrana Control 4.5 ± 0.17 a 47.4 ± 4.7 b 519.9 ± 8.9 bTBCA 4.85 ± 0.17 a 95.5 ± 4.6 a 560.5 ± 13.9 a

Bura Results: Percentage (%) germination of 3 varieties of Stylosanthes in Bura field station

S.hamata S. scabra S. seabrana

Control 11.0 ± 2.0 7.9 ± 1.9 49.5±6.2TBCA 10.5 ± 3.9 8.25 ± 0.25 48.7±4.1IBCA 13.6 ± 3.4 8.0 ± 0.0 42.5±4.5MZ 11.25 ± 1.010.1 ± 1.7 40.7±3.4

Stylosanthes at Maturity (90 days after planting amendment

Height stems Weight(branches)

Control 57.85±1.1 329±43 240 ± 5.8 TBCA 62.1 ± 1.8 396 ± 36 267.5 ± 2.5 IBCA 58.8 ±2.3 358 ±25.6 242.5 ± 9.6 Maize Cob 59.5 ±3.1 386 ± 242.5 ± 8.5

High weed pressure in Bura

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